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Sucrose Accumulation in Sugar Beet Under Drought Stress
Abstract
Drought stress may affect sucrose accumulation of sugar beet by restricting leaf development and storage root growth. The objective of this study was to identify changes occurring in the storage root of Beta beets in growth characteristics and ions and compatible solutes accumulation under drought with regard to sucrose accumulation. Two pot experiments were conducted: (1) sugar beet well supplied with water (100 % water capacity), under continuous moderate (50 %) and severe drought stress (30 %), (2) sugar beet and fodder beet well supplied with water (100 %) and under continuous severe drought stress (30 %). Under drought stress, the ratio of storage root to leaf dry matter of sugar beet decreased indicating a different partitioning of the assimilates. The sucrose concentration of the storage root was reduced. In the root, the number of cambium rings was only slightly affected, although drought stress was implemented already 6 weeks after sowing. In contrast, the distance between adjacent rings and the cell size was considerably restricted, which points to a reduced expansion of existing sink tissues. The daily rate of sucrose accumulation in the root showed a maximum between 16 and 20 weeks after sowing in well-watered plants, but it was considerably reduced under drought stress. The concentration of compatible solutes (K, Na, amino acids, glycine betaine, glucose and fructose) decreased during growth, while it was enhanced because of drought. However, when sucrose concentration was added, a constant sum of all examined solutes was found throughout the vegetation period. It was similar in sugar beet and in fodder beet despite different concentrations of single solutes, and the total sum was not affected by water supply. A close negative relationship between the concentration of compatible solutes and sucrose occurred. It is therefore concluded that the accumulation of compatible solutes in the storage root of Beta beets under drought might be a physiological constraint limiting sucrose accumulation.
... Genotypic differences in the number and distance of the cambium rings have been described between sugar beet and fodder beet [8,9]. Beta Vulgaris cultivars can be divided into four cultivar groups: Leaf Beet, Garden Beet, Fodder Beet and Sugar Beet [10]. ...
... So far, the underlying shape and the real cell size distribution is unknown for sugar beet roots. We have refrained from correcting the measured cell size, as in other published studies of sugar beet roots, no adjustment was made either for real cell size [5,9,12,14,30,31]. ...
... For vascular cells, there is no size reference yet. The cell sizes measured in the storage parenchyma were on the lower end of the range reported in other studies [9,30,31]. This was mainly influenced by the fact that in the presented workflow, only the first 6 mm from the periphery to the center were considered. ...
Background
Cell characteristics, including cell type, size, shape, packing, cell-to-cell-adhesion, intercellular space, and cell wall thickness, influence the physical characteristics of plant tissues. Genotypic differences were found concerning damage susceptibility related to beet texture for sugar beet (Beta vulgaris). Sugar beet storage roots are characterized by heterogeneous tissue with several cambium rings surrounded by small-celled vascular tissue and big-celled sugar-storing parenchyma between the rings. This study presents a procedure for phenotyping heterogeneous tissues like beetroots by imaging.
Results
Ten Beta genotypes (nine sugar beet and one fodder beet) were included to establish a pipeline for the automated histologic evaluation of cell characteristics and tissue arrangement using digital image processing written in the programming language R. The identification of cells has been validated by comparison with manual cell identification. Cells are reliably discriminated from intercellular spaces, and cells with similar morphological features are assigned to biological tissue types.
Conclusions
Genotypic differences in cell diameter and cell arrangement can straightforwardly be phenotyped by the presented workflow. The presented routine can further identify genotypic differences in cell diameter and cell arrangement during early growth stages and between sugar storage capabilities.
... Genotypic differences in the number and distance of the cambium rings have been described between sugar beet and fodder beet [8,9]. Genetic differences in cell size are determined very early during plant development [10,11], which could be helpful for the screening of genotypes in the context of breeding. ...
... So far, the underlying shape and the real cell size distribution is unknown for sugar beet roots. We have refrained from correcting the measured cell size, as in other published studies of sugar beet roots, no adjustment was made either for real cell size [5,9,10,12,26,27]. But as the possible error is the same for all genotypes (or other treatments) a comparison of those will always be correct ...
... For vascular cells, there is no size reference yet. The cell sizes measured in the storage parenchyma were on the lower end of the range reported in other studies [9,26,27]. This was mainly in uenced by the fact that in the presented work ow, only the rst 6 mm from the periphery to the center were considered. ...
Background
Cell characteristics, including cell type, size, shape, packing, cell-to-cell-adhesion, intercellular space, and cell wall thickness, influence the physical characteristics of plant tissues. Genotypic differences were found concerning damage susceptibility related to beet texture for sugar beet (Beta vulgaris). Sugar beet storage roots are characterized by heterogeneous tissue with several cambium rings surrounded by small-celled vascular tissue and big-celled sugar-storing parenchyma between the rings. This study presents a procedure for phenotyping heterogeneous tissues like beetroots by imaging.
Results
Ten Beta genotypes (nine sugar beet and one fodder beet) were included to establish a workflow for the automated histologic evaluation of cell characteristics and tissue arrangement using digital image processing written in the programming language R. The identification of cells has been validated by comparison with manual cell identification. Cells are reliably discriminated from intercellular spaces, and cells with similar morphological features are assigned to biological tissue types.
Conclusions
Genotypic differences in cell diameter and cell arrangement can straightforwardly be phenotyped by the presented workflow. The presented routine can further identify genotypic differences in cell diameter and cell arrangement during early growth stages and between sugar storage capabilities.
... Compatible solutes or osmoprotectants are small, non-toxic molecules that protect cells against stress and function in reactive oxygen species (ROS) scavenging, maintaining membranes and protein structures [91]. Accordingly, in beets, increased levels of compatible solutes, including glycine betaine, proline, glucose, fructose [49,68], raffinose [61,72], and sucrose [71,77], during salt or water stress, maintain photosynthesis and stomatal conductance [70,92]. Under water stress, accumulation of osmoprotectants reduces the osmotic potential in sugar beet cells [40,71], facilitating water influx [18]. ...
... Under water stress, accumulation of osmoprotectants reduces the osmotic potential in sugar beet cells [40,71], facilitating water influx [18]. In addition, in sugar beet shoots and wild beet leaves, inorganic ions such as K + , Na +, and Cl − are involved in osmotic adjustment in response to salinity stress [59,68,70,90]. Roots can not absorp water efficiently due to the high osmotic pressure in saline conditions, resulting in physiological drought [21,93], and they must exclude almost all the toxic ions (97-98%) from the transpiration stream while absorbing water. ...
... Recently, sucrose synthases (SuSy), which take part in sucrose synthesis and decomposition in plants, have been found to be accumulated in sugar beet roots under salt stress, suggesting that osmotic regulation in roots may be related to the accumulation of these enzymes [53]. Furthermore, some studies have shown that augmentation of compatible solutes could also reduce sucrose accumulation in roots due to the assimilation of partitioning adjustments between storage carbohydrates and structural carbohydrates [68,77,108]. In contrast, it has recently been shown that enhancement of soluble sugars in sugar beet leaves is observed when plants are exogenously treated with proline [9]. ...
Cultivated beets, including leaf beets, garden beets, fodder beets, and sugar beets, which belong to the species Beta vulgaris L., are economically important edible crops that have been originated from a halophytic wild ancestor, Beta maritima L. (sea beet or wild beet). Salt and drought are major abiotic stresses, which limit crop growth and production and have been most studied in beets compared to other environmental stresses. Characteristically, beets are salt-and drought-tolerant crops; however, prolonged and persistent exposure to salt and drought stress results in a significant drop in beet productivity and yield. Hence, to harness the best benefits of beet cultivation, knowledge of stress-coping strategies, and stress-tolerant beet varieties, are prerequisites. In the current review, we have summarized morpho-physiological, biochemical, and molecular responses of sugar beet, fodder beet, red beet, chard (B. vulgaris L.), and their ancestor, wild beet (B. maritima L.) under salt and drought stresses. We have also described the beet genes and noncoding RNAs previously reported for their roles in salt and drought response/tolerance. The plant biologists and breeders can potentiate the utilization of these resources as prospective targets for developing crops with abiotic stress tolerance.
... Opposite to all other environments, the environments NZ18 and NZ19 did not show big differences between the measuring positions. The reason might be low overall compressive strength as a consequence of drought stress, which particularly restricts the expansion of the inner cambium rings (Hoffmann, 2010). Thus, the cell size, which is normally larger in the inner part of the root, is also reduced and more similar to the outer cell size (Nause et al., 2020). ...
... In sugar beet, moderate drought stress causes an increase of the sugar content because of the loss of water (Bloch et al., 2006); as at the sites IfZ18 and SZ18. However, severe drought stress reduces sugar accumulation and thus sugar content because of sincere metabolic disturbance (Hoffmann, 2010); as found in the environments NZ18 and NZ19 with low root yield and low sugar content. Obviously, the tissue strength decreased under severe drought stress, too. ...
... Obviously, the tissue strength decreased under severe drought stress, too. The main reason for low root yield under severe drought stress is a decrease in cell expansion, as Hoffmann (2010) confirmed for sugar beet in a comparison of drought stressed and well-watered roots. Drought also affected the relation of root yield and tissue strength: Low average yield was associated with low tissue strength in the extreme environments NZ 18 and 19, while in the other environments with largely normal growing conditions tissue strength was not as clearly related with root yield. ...
Tissue strength of sugar beet (Beta vulgaris L.) roots could be an interesting breeding target, as it is a possible indicator for storability and influences the manufacturing process. The objective of this study was to analyse the importance of genotype and environment and their interaction on three texture parameters (puncture resistance, tissue firmness, and compressive strength) and to investigate the range of tissue strengths of commercial sugar beet genotypes. For that purpose, two trial series were conducted with 6 sugar beet genotypes in 7 environments across Germany in 2018 and 2019. A screening was performed with 12 commercial genotypes at one site in 2020. Tissue firmness and compressive strength were closely correlated with the puncture resistance of sugar beet roots. The genotype effect was distinctly higher for the texture parameters than for yield and quality parameters, while the genotype by environment interaction was negligible, allowing a selection based on few sites. For both genotype and environment, compression strength was closely related to the relative sugar content of the beets. Commercial genotypes also covered a wide range of tissue strengths. These differences might affect harvest damage, storage losses, and subsequent processing steps in the factory. This article is protected by copyright. All rights reserved Tissue strength is largely determined by genotype Genotype by environment interaction on tissue strength is negligible Commercial genotypes differ considerably in tissue strength Tissue strength seems to have a causal relation to sugar content
... It is an outbreeding, biennial, and diploid (2n = 18) plant with an estimated genome size of ~ 714 to 758 megabases (Mb), grown in temperate and subtropical climates of the world (Dohm et al. 2014). Sugar beet has an enormous importance in the sugar industry, accounting for 30% of the world's yearly sugar production after sugar cane (Hoffmann 2010). In addition, they provide essential raw materials for bioethanol, health, pharmaceuticals, animal feed, and food-related industries (Yolcu et al. 2021(Yolcu et al. , 2022. ...
... maritima (Beta maritima), which grows on the shores of the Mediterranean Sea and the Atlantic Ocean. Due to its adaptation to highly saline environments, B. maritima is able to withstand more severe salt stress compared to cultivated beets (Hoffmann 2010;Biancardi et al. 2012;Rozema et al. 2014). Also the increased drought tolerance of B. maritima was demonstrated (Ribeiro et al. 2016;Parreira et al. 2015). ...
Main conclusionAlthough sugar beet is a salt- and drought-tolerant crop, high salinity, and water deprivation significantly reduce its yield and growth. Several reports have demonstrated stress tolerance enhancement through stress-mitigating strategies including the exogenous application of osmolytes or metabolites, nanoparticles, seed treatments, breeding salt/drought-tolerant varieties. These approaches would assist in achieving sustainable yields despite global climatic changes.AbstractSugar beet (Beta vulgaris L.) is an economically vital crop for ~ 30% of world sugar production. They also provide essential raw materials for bioethanol, animal fodder, pulp, pectin, and functional food-related industries. Due to fewer irrigation water requirements and shorter regeneration time than sugarcane, beet cultivation is spreading to subtropical climates from temperate climates. However, beet varieties from different geographical locations display different stress tolerance levels. Although sugar beet can endure moderate exposure to various abiotic stresses, including high salinity and drought, prolonged exposure to salt and drought stress causes a significant decrease in crop yield and production. Hence, plant biologists and agronomists have devised several strategies to mitigate the stress-induced damage to sugar beet cultivation. Recently, several studies substantiated that the exogenous application of osmolytes or metabolite substances can help plants overcome injuries induced by salt or drought stress. Furthermore, these compounds likely elicit different physio-biochemical impacts, including improving nutrient/ionic homeostasis, photosynthetic efficiency, strengthening defense response, and water status improvement under various abiotic stress conditions. In the current review, we compiled different stress-mitigating agricultural strategies, prospects, and future experiments that can secure sustainable yields for sugar beets despite high saline or drought conditions.
... In beet the amount of sugar and bagasse is expressed in terms of fresh matter; its concentration can also increase, although in terms of dry matter, the sugar content is reduced at the expense of the increase in fiber (Hoffmann, 2010). The results from production and distribution of fresh weight in most of the variables showed statistical dependency on the factor year, but with variations of lower magnitude. ...
... En remolacha la cantidad de azúcar y bagazo se expresan en términos de materia fresca; la concentración de ésta también puede aumentar, pero en términos de materia seca, el contenido de azúcar se reduce a expensas del aumento en fibra (Hoffmann, 2010). Los resultados de producción y distribución de peso fresco, en la mayoría de las variables presentaron dependencia estadística del factor año, pero con variaciones de menor magnitud. ...
La remolacha azucarera (Beta vulgaris L.) es la segunda fuente de azúcar en el mundo. El área de adaptación se localiza en países del hemisferio norte. En México se han propuesto varios cultivos para obtención de biocombustibles entre los que destaca la remolacha azucarera. El objetivo del trabajo fue evaluar el potencial productivo de la remolacha azucarera bajo condiciones de riego en el noreste de Tamaulipas; el cual se caracteriza por el monocultivo de sorgo y maíz. La evaluación se hizo durante el ciclo O-I en los años 2010 y 2011 en el Campo Experimental Río Bravo del INIFAP. En nueve variedades comerciales se midió el largo y diámetro máximo de la raíz, producción, distribución de biomasa seca y fresca de raíz, oBrix, rendimiento y producción estimada de azúcar e incidencia de enfermedades. El paquete tecnológico y los costos de producción fueron hechos con adecuaciones a los cultivos predominantes. La presencia de enfermedades fue un riesgo para el cultivo, inducido por la susceptibilidad varietal, cantidad y distribución de la precipitación. Bajo las condiciones de este estudio es posible producir remolacha azucarera en forma comercial hasta 54 t ha1 y 18 oBrix. El costo de la semilla representó la mayor inversión en el paquete tecnológico (38%).
... Here, one individual per seed family and block received the 'control' treatment by keeping soil moisture of the pot at 60% of total soil water capacity (Majer, 2008). The other individual was kept under severe drought with no more than 30% of the soil water capacity (Hoffmann, 2010). Soil moisture was checked by weighing pots every 2 days. ...
For terrestrial plant communities, the increase in frequency and intensity of drought events is considered as one of the most severe consequences of climate change. While single‐species studies demonstrate that drought can lead to relatively rapid adaptive genetic changes, the evolutionary potential and constraints to selection need to be assessed in comparative approaches to draw more general conclusions. In a greenhouse experiment, we compare the phenotypic response and evolutionary potential of two co‐occurring grassland plant species, Bromus erectus and Trifolium pratense , in two environments differing in water availability. We quantified variation in functional traits and reproductive fitness in response to drought and compared multivariate genetic variance–covariance matrices and predicted evolutionary responses between species. Species showed different drought adaptation strategies, reflected in both their species‐specific phenotypic plasticity and predicted responses to selection indicating contrasting evolutionary potential under drought. In T. pratense we found evidence for stronger genetic constraints under drought compared to more favourable conditions, and for some traits plastic and predicted evolutionary responses to drought had opposing directions, likely limiting the potential for adaptive change. Our study contributes to a more detailed understanding of the evolutionary potential of species with different adaptive strategies in response to climate change and may help to inform future scenarios for semi‐natural grassland ecosystems.
... At the middle of the season, sugar loss was at the lowest level then decreased insignificantly at the middle of the season in both production lines. This might happen due to the insignificant reduction in K, Na and α-N levels that occurred in the middle of the season (Hoffmann 2010). Consequently, the sugar loss in molasses increased from 2.50.4 and 2.40.6% in the middle of season to 3.10.5 and 3.00.2% ...
... Lower or no sucrose content in carrot cultivars under drought can be also attributed to the utilization of sucrose in carrot cytoplasm under effect of abiotic stimuli (Cavagnaro, 2019). Restricted sucrose accumulation might contribute to physiological constraint due to ions and compatible solute accumulation (Hoffmann, 2010). Moreover, the sucrose contents under drought response also depend upon the enzymatic cleavage activity. ...
The effects of drought stress on plant growth and development are getting more pronounced due to increasing influence
of climate change on environmental stresses. Current study was devised to explore the drought effects on eight commercial carrot
cultivars, having different root colors as a base for further studies to understand the response of carrot. Drought stress for 10 days
was applied to carrot plants at taproot formation stage in semicontrolled greenhouse. The results revealed that orange and yellow
colored carrot cultivars exhibited the least decline in physiological functioning (relative water contents and dry matter) that assisted
in maintaining higher yield and quality attributes in contrast to purple and black carrot cultivars. However, anthocyanin contents
in nonpurple cultivars Tendersweet and Solar Yellow showed 72% decrease, whereas in purple carrot cultivars 3-fold increase was
observed in Eregli Black and Cosmic Purple. Beta-carotene contents showed 59% decrease in cultivar Eregli Black under drought;
however, it was increased in cultivars Solar Yellow and Coral Orange by 17% and 3%, respectively. Sugar accumulation exhibited
variable response of carrot cultivars; minimal sucrose contents in cultivars Cosmic Purple, Solar Yellow and Tendersweet were
detected after they were subjected to drought. Overall, the results showed that cultivars Atomic Red and Coral Orange performed
well under water scarce condition. We believe this study may help the researchers to move forward in understanding the
... Moreover, they play a crucial function in protecting plant cells from oxidative stress by removing reactive oxygen species [20,32,35]. It has been shown that sucrose accumulates in plant tissues under drought stress [36][37][38]. PEG, sucrose, mannitol, and sorbitol have been the main chemicals for imposing osmotic pressure in vitro. PEG has reportedly been used to impose physiological drought in plants [28,29,39,40]. ...
Plants are constantly faced with biotic or abiotic stress, which affects their growth and development. Yield reduction due to biotic and abiotic stresses on economically important crop species causes substantial economic loss at a global level. Breeding for stress tolerance to create elite and superior genotypes has been a common practice for many decades, and plant tissue culture can be an efficient and cost-effective method. Tissue culture is a valuable tool to develop stress tolerance, screen stress tolerance, and elucidate physiological and biochemical changes during stress. In vitro selection carried out under controlled environment conditions in confined spaces is highly effective and cheaper to maintain. This review emphasizes the relevance of plant tissue culture for screening major abiotic stresses, drought, and salinity, and the development of disease resistance. Further emphasis is given to screening metal hyperaccumulators and transgenic technological applications for stress tolerance.
... The osmotic adjustment has been widely recognized as a drought tolerance mechanism in plant species, and soluble sugars such as sucrose, glucose, and fructose act as essential osmoregulants during a series of metabolic processes under drought stress (Couée et al. 2006;DaCosta and Huang 2006;Hoffmann 2010;Liu et al. 2015). In drought-treated creeping bentgrass, soluble sugars were considered to be the predominant contributor to osmotic adjustment (Liu et al. 2015). ...
Drought stress is one of the most important environmental factors resulting in a variety of physiological and biochemical damages in plants. The objectives of this study were to (1) determine whether foliar application of ethionine (ETH) could effectively improve drought tolerance and (2) reveal how the foliar application of ETH alleviated drought stress from physiological and biochemical perspectives. Tall fescue (Festuca arundinacea cv. ‘Starfire’) was grown in a growth chamber and foliar applications were with 10 mL 250 mg·L−1 ETH every five days when plants were well-watered (control + ethionine) or unirrigated (drought + ethionine). Drought stress, in tall fescue, as expected, significantly decreased turf quality, relative leaf water content, photochemical efficiency, net photosynthetic rate, stomatal conductance, intercellular CO2 concentration, and transpiration rate. Drought stress increased electrolyte leakage as well as the content of malondialdehyde, hydrogen peroxide, and superoxide anion. Foliar application of ETH effectively mitigated drought damages by enhancing root viability, activities of antioxidant enzymes (peroxidase, catalase, ascorbate peroxidase, and monohydroascorbate reductase), and increasing contents of soluble sugars (sucrose, glucose, and fructose) and isopentenyladenosine. The results from this study suggested that the mitigation of ETH application on drought stress could be attributed to the enhanced drought tolerance through sustaining root viability, protecting cellular membrane integrity, enhancing osmotic adjustment, and regulating endogenous hormones in tall fescue.
... This was also shown in this study, in which the increased values of molasses formation components had no determining effect on the WSY (Figure 2e), and its value was determined rather by RY. However, the finding of Hoffmann [40] that the concentration of molasses formation components decreases with higher root volume and mass was not supported. ...
The application of biostimulants in agriculture is considered an economically and ecologically acceptable and, above all, a sustainable method of cultivation of field crops. This study aimed to investigate the impact of biostimulating agents on the production and growth parameters of the sugar beet. In 2018 and 2019, an experiment was conducted in which the effect of four types of treatment (B0–B3) on two varieties of sugar beet (Alpaca, Gorila) was observed. The results show that the beets treated with treatment type B3 (combination of humic acids, essential amino acids, biopolymers, and soil bacteria) had the significantly highest yield of roots compared with the control type. However, parameters such as sugar content, polarized sugar yield, white sugar content, and white sugar yield were the highest in condition B2, treated with an agent containing soil bacteria. Furthermore, biostimulants positively affected the leaf area index, with significant growth observed, especially in condition B3. Another important finding was that in the interaction analysis, the biostimulants had positive effects in dry conditions and on elevated values of traits of Alpaca variety caused by treatment in condition B2. In terms of relationships between individual parameters, an interesting finding was that there was only a weak relationship between root yield and sugar content (Rs = 0.0715), which indicates that biostimulants increase production size while maintaining or increasing its quality.
... Time during which carrot was exposed to low atmospheric humidity has a negative influence on key metabolites content. A related trend has been shown on beet under drought stress with the decrease of sucrose accumulation (Hoffmann, 2010) and the accumulation of osmoregulants compounds, including fructose and glucose (Bloch et al., 2006;Yakushiji et al., 1996). Carotenoid content variation according to drought stress is subtler. ...
Sugars and carotenoids are recognized as key quality compounds in vegetables due to their sensory and nutritional attributes. Ensuring a guaranteed content for these compounds in carrot crop is a major challenge for producers and breeders. Widely involved in plant acclimation mechanisms, the environment significantly influences their content. A multi-environment trial over two years was used in this study to identify the environmental determinism of carotenoid and sugar accumulation. After a fine characterization of cropping places in dissecting climatic variables, pedological conditions and cultural practices, PLSr models were used for predictive purposes to determine and prioritise pedoclimatic factors and cultural practices involvement. Interestingly, distinctive patterns are observed between sugars and carotenoids. Pedoclimatic factors and cultural practices effects are similar regardless studied carotenoid, with a differential effect in accumulation according to α-branch and β-branch carotenoids. For sugar metabolism, a reverse effect of leading factors is observed depending on sugars class. Our study brings to light the overall limiting effect of some climatic factors as time exposure to low temperature or atmospheric humidity. In contrast, pedological factors were shown to enhance sugar and carotenoid content in carrot, mainly phosphorus, potassium, iron and boron. This study provides useful information for carrot producers to adapt their cultural practice depending on crop place to reach a guaranteed quality in crops. Moreover, our work paves the way for a better understanding of the mechanisms underlying the major pedoclimatic factors and cultural practices effects on the accumulation of key compounds.
... Tolerance mechanisms allow plants to survive within their genetic potential and include morphophysiological responses, such as reducing leaf expansion and stomatal conductance, and biochemical responses such as improving the antioxidant system and osmotic adjustment (Reddy et al. 2004;Harb et al. 2010). For example, water deficit reduces growth and biomass allocation among the organs of root vegetables such as sugar beets, carrots and radishes (Sørensen et al. 1997;Hoffmann 2010;Stagnari et al. 2018). ...
Plant growth and development depends on water availability and a scarcity or excess can reduce the production of root crops such as radishes. Thus, adequate irrigation levels for radish plants are essential to avoid water stress, and strategies should be developed to overcome negative stress effects and improve tuberous root production. Here, we aimed to determine the effects of exogenous ascorbic acid (AA) and irrigation levels on radish growth, biomass allocation, and photosynthetic responses. Radish plants were irrigated with a water holding capacity (WHC) of 100% (W100, control), 70% (W70), and 50% (W50) and foliar sprayed with 0 and 2 mM AA. Growth parameters (root diameter, length and volume; and leaf number and area), biomass accumulation (shoot and root fresh weight; shoot, root and total dry weight), biomass allocation (shoot/root ratio and organ mass fractions) and gas exchange (carbon assimilation rate, stomatal conductance, transpiration, intercellular CO2 concentration and instantaneous carboxylation efficiency) were evaluated. The growth of radish plants was impaired when irrigated with W100, probably due to water-logging in the soil, which reduced shoot and root growth and the carbon assimilation rate (A) compared with W50 and W70. Ascorbic acid affected biomass allocation parameters and instantaneous carboxylation efficiency (A/Ci), but not growth and biomass accumulation. W70 was the optimal condition for radish growth and biomass accumulation, regardless of exogenous AA.
... Drought is among the major growth limiting factors of crop production (Hoffmann, 2010;Chowdhury et al., 2021;Shabbir et al., 2021;Ali et al., 2021;Akhtar et al., 2022). It induces various biochemical and physiological changes in crops (Bahar et al., 2021;Islam et al., 2021;Ahmad et al., 2022aAhmad et al., , 2022bAbbas et al., 2022). ...
The calcium (Ca +2) molecules being an important intracellular messenger are involved in various signal trans-duction mechanisms in plants. Many external stimuli such as drought, cold, heat stress, metalloid stress (cop-per (Cu), cadmium (Cd), nickel (Ni), and arsenic), flooding, and salinity stress increase the free Ca +2 ions in the cytosol. The H + /Ca +2 antiporters and Ca +2-ATPases actively transport the cytosolic Ca +2 in intracellular organ-elles or apoplasts. Increase in Ca +2 concentration is sensed by calcium-binding proteins or Ca +2-sensors which lead to activation of CDPKs (Calcium-dependent protein kinases). These CDPKs regulate various genes responsive to stress to show phenotypic responses against stress stimuli. Hormonal signaling and their cross-talk with Ca +2 have been studied extensively but a thorough understanding of Ca +2 in stress tolerance is limited. This review describes the various aspects of Ca +2 involvement in sensing stress stimuli, signal transduction, role against various stress factors (including temperature extreme, salinity, flooding, metal-loids, and drought), the role of Ca +2 in the regulation of physiological processes, and Ca +2-ATPase.
... On the other hand, the distribution of glucose also corresponds to the nutrient status of the rhizosphere (Marschner, 1998;Hinsinger, 2001). Water stress inhibits glucose exudation (Calvo et al., 2019), and instead stimulates the accumulation of this compatible solute in roots (Palta and Gregory, 1997) to maintain physiological processes such as stomatal conductance, photosynthetic rate (Jacob and Lawlor 1991;Ghannoum and Conroy 2007), and expansion growth (Morgan, 1984;Bohnert and Sheveleva, 1998;Hoffmann, 2010). In contrast, the root secretion of glucose tends to increase as a strategy of plants to deal with P deficiency (Carvalhais et al., 2011). ...
Glucose is one of the low molecular weight components of root exudates to mediate the cross-talk between plants and microbes, but less is known about their contribution to drought resistance of plants and root-associated microbiome. To fill this knowledge gap, we optimized the visualization of glucose exudation and coupled it with another in situ tool – soil zymography ‒ as well as destructive analysis of enzyme kinetics (β-glucosidase; acid phosphomonoesterase) and microbial biomass. This helped identify how microbial functionality ‒ affected by drought and P limitation ‒ will show more resistance in the hotspots of soybean rhizosphere (grown in the rhizoboxes for 10 weeks) associated with arbuscular mycorrhizal fungi (AMF) symbiosis than those without AMF. Drought reduced glucose exudation, mainly allocated to root tips, and narrowed the rhizosphere enzymatic hotspot by three times. However, AMF inoculation enhanced glucose exudation compared to non-mycorrhizal plants and enlarged enzymatic hotspot area by 53% under drought condition. Despite the 50% reduction in β-glucosidase and acid phosphomonoesterase activities owing to water deficit, AMF symbiont triggered up to 36% enzyme activities in correlation with the non-mycorrhizal ones. Therefore, the drought resistance of these two enzymes was enhanced by up to 63% in mycorrhizal plants. The biomass of microbial phosphorus increased by 45% under drought AMF-conditioned plants. We conclude that the cooperation between soybean and AMF induced the formation of favorable microsites around the root, specifically in overlapping localities between rhizosphere and mycorrhizosphere, characterized by enhanced glucose release, increasing rhizosphere expansion, high enzyme activities and shortened substrate turnover time. This, in turn, contributed to the stronger resistance of microbial functions (e.g., enzyme expression) to drought stress in the rhizosphere hotspots. Thus, in response to AMF inoculation and consequent high glucose availability, rhizosphere microorganisms increased P mining rate in those hotspots remaining active despite water scarcity.
... Amylase activity in radish is promoted in cool temperatures, whereas in wheat, it is promoted in mild temperatures [56]. In addition, under dry conditions, sucrose was accumulated because sucrose acts as a compatible solute [57,58]. These previous studies suggested that the soluble sugar content in autumn is higher than that in spring because of promotion of amylase activity at low temperatures and drought stress. ...
Kimchi made from small-type (Altari) radishes grown in late spring is more pungent than that made from autumn-grown Altari radishes, which poses a major challenge in the kimchi industry. The mechanism through which the pungency of Altari radish changes seasonally has not been intensively investigated. In this study, three small-type radish cultivars with different pungency levels were cultivated in spring and autumn to identify the factors affecting the seasonal-dependent pungency of small-type radishes. The contents of pungency-related metabolite glucoraphasatin and other polar metabolites were analyzed. Although a previous study reported that the glucoraphasatin concentration affects the pungency of radish, in the current study, the concentration of neither glucoraphasatin nor its hydrolysis product (raphasatin) could fully explain the change in the pungency associated with radish cultivars grown in the two seasons. The change in the pungency of radish by season may be explained by the ratio of raphasatin content to total sweetness of sugars. In addition, the polar metabolites that differ with season were analyzed to identify seasonal biomarkers and understand the seasonal changed physio-biochemistry.
... (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.) plants, especially regarding potassium (Hasanuzzaman et al., 2018;Hoffmann, 2010;Mubarak et al., 2016). For instance, Altay and Aksu, (2020) observed that potassium application increased sugar content and found that a high potassium plant concentration increased carbohydrate synthesis and sugar content in sugar beet. ...
Increased soil drought events threaten the yields of sugar beet (Beta vulgaris L.) and other staples of arable production in central Europe. In this study we evaluated soil moisture and nutrients as impacted by a two and five % (wt) addition of biochar, manure and their blend to a loamy-sand Regosol. Cyclical soil drought was achieved by the controlled reduction of watering by 75% in pot experiments. Ongoing soil moisture and nutrient measurements were taken, and physiological parameters of sugar beet plants were analysed three weeks after the induced drought. At the end of the experiment (16 weeks) plants were harvested and their mass assessed, as well as their nutrient, pigment and sugar contents. In contrast to the addition of manure, soil volumetric water contents were two to three times greater after biochar amendment, compared to the control soil. Porewater analysis revealed that nutrient leaching (e.g., NO3⁻, K⁺) from manure addition to soil was reduced when biochar was blended in (by ≤86% compared to manure alone). Crop analysis showed that leaf gas exchanges were moderated during drought following soil amendment, and leaf and tuber yields were increased furthest when combined biochar-manure blends were applied (> 2-times compared to the control). Perhaps most importantly, the advantageous soil conditions induced by the combined biochar and manure addition also resulted in significantly increased sugar contents in plants (2.4-times) pointing to immediate practical applications of these results in the field.
... However, there are clear indications from other studies that allow the conclusion to be drawn that sugar beet is in most growth stages sink, not source limited (Hoffmann, 2019;Hoffmann et al., 2020). Therefore, the assimilate supply should not be the limiting factor even under drought when leaves are wilted (Hoffmann, 2010). Also is described in the literature that at the onset of a drought period, the sink and therefore the activity in storing assimilates are limited (Körner, 2013). ...
Drought stress restricts sugar beet growth and yield formation. For the development of adapted varieties, reasons for high water demand in certain growth periods and for genotypic differences in water use efficiency (WUE) were investigated. In 2019 and 2020, different drought stress periods were simulated in pot trials in the greenhouse with four sugar beet genotypes by reducing the water supply to 50% of the water holding capacity. With unlimited water supply, water consumption developed in parallel to the growth rate. This indicates that water demand is driven by growth rate. Therefore, early drought stress in the period with highest growth rate caused strongest yield reductions, which could not be compensated later in the season. Unlike sugar yield, water consumption differed among genotypes, resulting in genotypic differences in WUE. However, no relevant genotype by water supply interaction occurred, giving no indication for drought tolerance of the genotypes with high WUE. WUE is rather determined by the sugar yield potential of a genotype than by water supply. Therefore, sugar beet genotypes should be selected for their sugar yield potential when breeding for environments with varying water supply.
... The percentage of sugar depends on the substitution of non-sucrose compounds with sucrose during root growth and is affected by water and nutrients. Sucrose storage is limited by the increasing level of osmolyte [79]. Studies [14] have shown that the percentage of sugar decreased is due to heat stress. ...
Two field experiments were carried out during 2018-2019 at the Hamedan and Qom sites, which are different ecological locations of Iran. Hamedan was selected as a temperate climate and Qom as semi-arid to study some of the morphological and physiological traits of fodder beet in various climatic conditions. The experimental map was designed as a split-split-plot in the form of a randomized complete block with three replications. The main plots were assigned three levels of methanol (i.e., control, 15, and 30% by volume). The sub-plots were restricted to two glycine betaine (GB) concentrations (i.e., control and four grams per liter of methanol consumed, and the sub-sub-plots consisted of six different genotypes of fodder beet). The results showed that root length, root and foliage yield/ha, as well as sugar content increased with the incremental level of methanol and/or GB concentration. Foliar application of methanol and GB also significantly changed the qualitative parameters including sodium content, catalase value, crude protein percentage, and dry matter digestibility. It should be noted that two sites differed in most of the investigated traits, so that Hamedan treatment had a more active role on fodder beet growth, yield, and quality compared with Qom. Meanwhile, there was a significant difference between fodder beet genotypes. Generally, spraying fodder beet with 15%by volume methanol or GB with concentration of four grams per liter of methanol is the recommended treatment for raising forage yield under the ecological circumstances of this research.
... For the few cases in which yield effects from irrigation treatments were observed, generally responses were consistent with water stress being an important cause of yield loss in sugar beet (Rytter, 2005;Bloch et al., 2006;Hoffmann, 2010). However, only the lowest irrigation rate exhibited notable yield reductions, and only during one year (2010), suggesting that sugar beet in our study was resilient to less severe deviations from an optimal irrigation rate. ...
... Our experiments here concluded that nitrogen greatly increased the sugar content and tuber yield of sugar beet. What's more, water supply could also significantly increase sugar yield of sugar beets under sufficient nitrogen conditions, which is proved by previous studies 48,54,58 and our study. ...
A 2-year field experiment was conducted to analyze the growth conditions, physical features, yield, and nitrogen use efficiency (NUE) of sugar-beet under limited irrigation conditions in northeast of China. A cultivar H003 was used as plant materials; six treatments (C1–C6) were included: C1, no nitrogen applied, rain-fed; C2, nitrogen (120.00 kg ha ⁻¹ ), rain-fed; C3, no nitrogen applied, hole irrigation for seeding; C4, nitrogen (120.00 kg ha ⁻¹ ), hole irrigation for seeding; C5, no nitrogen applied, hole irrigation for seeding; and C6, nitrogen (120.00 kg ha ⁻¹ ), hole irrigation for seeding, and irrigation at foliage rapid growth stage. The irrigation supply was only 500 mL/plant once. Results showed C6 showed the highest chlorophyll content, dry matter accumulation, yield, etc. and had the best NUE among all the treatments. In conclusion, under the routine fertilization conditions of northeast of China, the cultivation measure of hole irrigation 500 mL/plant for seeding combined with irrigation 500 mL/plant at foliage rapid growth stage greatly improved sugar-beet yield and NUE.
... Due to its adjustment to a highly saline environments Beta vulgaris ssp. maritima is able to withstand more severe salt stress, compared to cultivated beets [12][13][14]. ...
Here we determined the impact of salt shock and salt stress on the level of DNA methylation in selected CpG islands localized in promoters or first exons of sixteen salt-responsive genes in beets. Two subspecies differing in salt tolerance were subjected for analysis, a moderately salt-tolerant sugar beet Beta vulgaris ssp . vulgaris cv. Huzar and a halophytic beet, Beta vulgaris ssp . maritima . The CpG island methylation status was determined. All target sequences were hyper- or hypomethylated under salt shock and/or salt stress in one or both beet subspecies. It was revealed that the genomic regions analyzed were highly methylated in both, the salt treated plants and untreated controls. Methylation of the target sequences changed in a salt-dependent manner, being affected by either one or both treatments. Under both shock and stress, the hypomethylation was a predominant response in sugar beet. In Beta vulgaris ssp . maritima , the hypermethylation occurred with higher frequency than hypomethylation, especially under salt stress and in the promoter-located CpG sites. Conversely, the hypomethylation of the promoter-located CpG sites predominated in sugar beet plants subjected to salt stress. This findings suggest that DNA methylation may be involved in salt-tolerance and transcriptomic response to salinity in beets.
... As a consequence of this growth limitation, sugar is accumulated in the leaves and suggests a downregulation of photosynthesis as feedback regulation (Mäck and Hoffmann, 2006). Therefore, the assimilate supply is probably not the limiting factor (Hoffmann, 2010), but seems always high enough to maintain yield formation, even if light interception by the leaf canopy and assimilation is temporarily affected during growth (e.g. by drought stress). Hence, sugar beet is less sensitive to changes in growing conditions affecting canopy cover and can therefore provide stable yields under varying environmental conditions (Evans, 1975;Hoffmann et al., 2020), which leads to the absence of considerable GxE interactions. ...
Drought stress affects yield formation of sugar beet. Under climatic changes with longer periods of drought, the development of sugar beet varieties with a higher drought stress tolerance is gaining importance. Objectives of the study were to investigate genotypic differences in the response to different environments, especially drought stress, to define conditions in which sugar beet can best be selected for root yield and sugar content, and furthermore, to examine the relation between yield potential and yield stability. In 2018 and 2019, field trials were carried out with 6 genotypes at three drought-stressed sites, where an irrigation treatment allowed the comparison with optimal growth conditions, furthermore, trials with 3 N treatments were conducted. In the absence of diseases, no significantly different regression slopes of genotypes were observed for sugar yield in 17 environments. Hence, the trials provided no indication for a special adaptation of the genotypes to drought stress conditions. One reason might be a sink limitation of sugar beet growth. By contrast, a genotype by environment interaction existed for sugar content and root yield. The greatest genotypic discrimination to classify genotypes with either high root yield or sugar content was under optimal growing conditions. With increasing root yield, the sugar content declined similarly in all genotypes. For sugar yield, differences between the genotypes occurred in yield potential and yield stability. High yield potential was not necessarily associated with high yield stability. As it is important to achieve consistently high yields also with higher variability of climatic conditions, yield stability will increase in importance for future breeding.
... When temporary water stress appears at the early period, it can be said that it reduces sugar beet root yield importantly. Indeed, when young beet plants were exposed to the stress of water, it was found that sugar yield, the rate of photosynthesis and assimilation severely decreased (Monti et al., 2006) and storage roots showed significant changes (Hoffmann, 2010). Sahin et al. (2004) determined that the bacterial activity was higher at the early development stages. ...
Two experiments were conducted to investigate the of nine ACC deaminase-containing, IAA-producing, N 2-fixing and/or P-solubilizing bacteria, on the growth, yield, chlorophyll, macro-and micro-nutrient content, and selected morpho-physiological parameters of sugar beet, under five irrigation levels (150%, 100%, 75%, 50%, and 25% of water-holding capacity). The research was established according to factorial arrangement in randomized block experimental design of five water regimes, eleven treatments and five replications. The experiment was set up in two sets; and the first set was harvested after 65 days and the second set was done after 130 days. Inoculation with multi-traits bacteria stimulated overall plant growth, including sugar content, root and leaf yield and the leaf chlorophyll contents, and macro-and micro-nutrient uptake, which might partly contribute to the activation of the processes involved in the alleviation of the effect of water stress. According to the results, under water constraint at the level of 75, 50 and 25% of water-holding capacity, beet yield parameters BF4, BF6, Bio-organic and mineral fertilizer was found effective. As an average of the five water regimes, bacterial formulations increased dry storage root weight by 6.5-27.7% and 9.1-27.3% and dry leaf weight by 6.1-26.7% and 3.9-25.8% at the first and second trials, whereas, mineral fertilizers (NP) and bio-organic fertilizers increased dry storage root weight by 24.5% and 9.3-15.5% and 20.2 and 9.2-15.2%, and dry leaf weight by 23.5% and 11.7-23.2% and 22.2% and 3.3-21.9%, respectively, compared with control. Moreover, water stress in sugar beet plants was alleviated partially by the inoculation with bacterial strains. Our results provide strong evidence that the role of bacteria in the performance of sugar beet plants in the stressful environment of soils not only the improved plant growth, yield, and macro-and micro-nutrient content, but also the alleviation of water deficit and waterlogging stress. Bu araştırma; beş farklı sulama rejimi altında (su tutma kapasitesinin %150, %100, %75, %50 ve %25'i), ACC deaminaze içeren, IAA üretici, Azot fikseri ve Fosfat çözücü bakteri uygulamalarının şeker pancarının gelişimine, makro ve mikro besin elementi alımına ve bazı morfo-fizyolojik özellikleri üzerine olan etkisini belirlemek amacıyla yürütülmüştür. Araştırma, tesadüf bloklarında faktöriyel düzenlemeye göre beş su rejimi, on bir uygulama ve beş tekerrürlü olarak kurulmuştur. Denemeler biri 65 gün, ikinci ise 130 günlük olmak üzere iki set halinde yürütülmüştür. Çoklu özelliğe sahip bakteri aşılamaları; şeker oranı, kök ve yaprak verimi, yaprak klorofil içeriği, makro ve mikro element alımı dahil gelişmeyi teşvik etmiş ve ayrıca su stresinin etkisinin hafifletilmesinde yer alan süreçlerin aktivasyonuna kısmen katkıda bulunabilmiştir. Sonuçlara göre, su tutma kapasitesinin %75, %50 ve %25'i seviyesinde su kısıtı altında şeker pancarı verim parametreleri bakımından BF4 ve BF6 kombine bakteri, Biyo-organik ve mineral gübre uygulamaları etkin bulunmuştur. Beş sulama rejimi ortalaması olarak, bakteri formülasyonları, birinci ve ikinci deneme setinde sırasıyla, kuru kök-gövde ağırlığını %6,5-27,7 ve % 9,1-27,3 ve kuru yaprak ağırlığını ise % 6,1-26,7 ve % 3,9-25,8 oranında artırırken; kontrole kıyasla, sırasıyla, mineral gübre ve biyo-organik gübre uygulamaları sırasıyla kuru depo-kök ağırlığını % 24,5 ve % 9,3-15,5 ve %20,2 ve 9,2-15,2 ve kuru yaprak ağırlığını ise % 23,5 ve % 11,7-23,2 ve% 22,2 ve% 3,3-21,9 artırmıştır. Bakteri aşılamaları ile şeker pancarında su stresi kısmen hafifletilmiştir. Bu araştırma sonuçları, bakteri aşılamalarının stres koşullarındaki performansının sadece bitki gelişmesi, verim ve besin alımının iyileştirilmesinde değil, aynı zamanda su kısıtı ve fazla sudan kaynaklanan stresin hafifletilmesinde de güçlü kanıtlar sağlamıştır. Anahtar Kelimeler: Su stresi, besin alımı, bakteriler, enzim aktivitesi, hidrojen peroksit, malondialdehit ÇOMÜ Zir. Fak. Derg. (COMU J. Agric. Fac.) 2020: 8 (2): 301-317
... When temporary water stress appears at the early period, it can be said that it reduces sugar beet root yield importantly. Indeed, when young beet plants were exposed to the stress of water, it was found that sugar yield, the rate of photosynthesis and assimilation severely decreased (Monti et al., 2006) and storage roots showed significant changes (Hoffmann, 2010). Sahin et al. (2004) determined that the bacterial activity was higher at the early development stages. ...
Two experiments were conducted in order to investigate the of nine ACC deaminase-containing, IAA-producing, N2-fixing and/or P-solubilizing bacteria, on the growth, yield, chlorophyll, macro- and micro-nutrient content, and selected morpho-physiological parameters of sugar beet, under five watering regimes. The experiment was set up in two sets; and the first set was harvested after 65 days and the second set was done after 130 days. Inoculation with multi-traits bacteria stimulated overall plant growth, including sugar content, root and leaf yield and the leaf chlorophyll contents, and macro- and micro-nutrient uptake, which might partly contribute to the activation of the processes involved in the alleviation of the effect of water stress. According to the results, at the level of 75, 50 and 25% of WHC under water constraint, beet yield parameters BF4, BF6, Bio-organic and mineral fetilizer was found effective. As an average of the five water regimes, bacterial formulations increased dry storage root weight by 6.5-27.7% and 9.1-27.3% and dry leaf weight by 6.1-26.7% and 3.9-25.8% at the first and second trials, whereas, mineral fertilizers (NP) and bio-organic fertilizers increased dry storage root weight by 24.5% and 9.3-15.5% and 20.2 and 9.2-15.2%, and dry leaf weight by 23.5% and 11.7-23.2% and 22.2% and 3.3-21.9%, respectively, compared with control. Moreover, water stress in sugar beet plants was alleviated partially by the inoculation with bacterial strains. Our results provide strong evidence that the role of bacteria in the performance of sugar beet plants in stressful environment of soils not only the improved plant growth, yield, and macro- and micro-nutrient content, but also the alleviation of water deficit and waterlogging stress.
Background:
Properly reduced irrigation combined with nitrogen (N) application can be used to improve crop water use efficiency (WUE) in arid regions, but its effect on sugar beet is unknown at present. A two-year field experiment was conducted to evaluate the effects of N application (N0, 0; N1, 150; N2, 225 kg N ha-1 ) on the canopy production capacity (CPC), yield, and WUE of sugar beet under normal irrigation [W1, 70% of field capacity (FC)] and deficit irrigation (DI) (W2, 50% FC) in the early growth stage (EGS).
Results:
The results showed that the W2 treatment reduced the CPC by reducing gas exchange, leaf area index (LAI), and chlorophyll content (SPAD value) of sugar beet leaves compared to the W1 treatment. However, DI combined with N application increased these parameters. Specifically, N application increased the net photosynthetic rate (Pn) by 40.7% by increased gas exchange, SPAD, and LAI compared to the N0 treatment. In addition, N application increased WUE by 12.5% by increasing thickness of upper surface, stomatal aperture, and cross-sectional area of petiole. This ultimately led to a significant increase in taproot yield (TY) (19.7%) and sugar yield (SY) (57.6%). Although the TY of the N2 treatment were higher than that of the N1 treatment, the SY and WUE did not increase significantly and the harvest index decreased significantly by 9.3%.
Conclusion:
DI combined with 150 kg N ha-1 in the EGS of sugar beet increases the WUE in the arid areas while avoiding yield loss by improving the CPC. This article is protected by copyright. All rights reserved.
Многолетними исследованиями ученых выявлено, что одним из основных лимитирующих факторов, регулирущих продуктивность зерновых культур, является наличие в почве элементов питания растений. Возделывание интенсивных сортов зерновых культур отличается повышенными требованиями к пищи и при их оптимизации в состоянии сформировать высокий урожай. Поэтому, разработка приемов применения удобрений при нулевой обработке озимой пшеницы в условиях богарного земледелия при дефиците почвенной влаги с выбором наиболее рациональных норм стимуляторов роста, микроудобрений, биологических удобрений в сравнительном изучении с рекомендованными нормами минеральных удобрений, а также с испытанием системных гербицидов нового поколения представляют особый интерес для науки и имеют важную практическую значимость при производстве зерна озимой пшеницы. Так, по результатам двухлетних исследований получены вполне удовлетворительные урожаи зерна озимой пшеницы на уровне 15,8 ц/га сформировались при обработке семян стимулятором роста Вымпел - 0,5 л/т и с микроудобрением Оракул семена 1,0 л/т в момент протравливания фунгицидом Бункер в норме 0,4 л/т, при ранневесенней обработки посевов в фазе кущения со стимулятором роста Вымпел - 0,5 л/га, микроудобрением Оракул мультикомплекс – 2,0 л/га, что способствовали повышению урожайности зерна на 7,0 ц/га по сравнению с контрольным необработанным вариантом опыта. Вполне хороший урожай зерна 18,4 ц/га за два года обеспечивались при обработке семян вышеназванными препаратами и двухкратной обработкой посевов озимой пшеницы в фазе ранневесенного кущения с обработкой посевов гербицидом «Балерина» 0,5 л/га и в фазе флагового листа стимулятором роста Вымпел – 0,5 л/га и микроудобрениям Оракул мультикомплекс в норме 2,0 л/га соответствующими нормами расхода рабочей жидкости 250 л/га согласно схемы опытов.
Экспopт хлoпкoвoгo вoлoкнa в Туpкестaнскoй oблaсти имеет вaжнoе стpaтегическoе знaчение для pеспублики Кaзaхстaн. Хлoпкoвoдствo является вaжнoй oтpaслью сельскoгo пpoизвoдствa для текстильнoй и пищевoй пpoмышленнoсти. В 2020 гoду пoд хлoпчaтникoм былa зaсеянo 131,2 тысяч гектapoв. Сpедняя уpoжaйнoсть сoстaвилa 26,2 ц/гa, пpи вaлoвoм сбopе хлoпкa-сыpцa 344,3 тысяч тoнн. Хлoпкoсеющей зoне Туpкестaнскoй oблaсти oднa из пpoблем нa сегoдня этo пoливнaя вoдa, кoтopaя течет пo pеке Сыpдapье. В вегетaциoнный пеpиoд мaссoвoгo цветения пpoисхoдит oднoвpеменнoе пoтpебление вoды, чтo зaтpудняет ситуaцию. Oснoвными пoтpебителями в этoт пеpиoд вoды являются Мaктaapaльский, Жетысaйский, Шapдapинский paйoны oбщaя плoщaдь этих теppитopий зaнимaет oкoлo 90 тысяч гектapoв. В связи с этoй ситуaцией дефицит пoливнoй вoды в летний вегетaциoнный пеpиoд сoстaвляет дo 40-45% oт тpебуемoгo oбъемa пoливнoй вoды. Вo вpемя цветения пpи фopмиpoвaнии плoдoв хлoпчaтник пoтpебляет oчень бoльшoе кoличествo вoды, сутoчный paсхoд дoстигaет 95-105 м3 /гa., a к кoнцу вегетaции сутoчнaя пoтpебнoсть сoстaвляет 45-55 м3 /гa. В ТOO «СХOС хлoпкoвoдствa и бaхчевoдствa», в селекциoннoм нaпpaвлении стoят oчень вaжные зaдaчa пo пoвышению хoзяйственнo-ценных пoкaзaтелей хлoпкoвoгo вoлoкнa. Туpкестaнскaя oблaсть является сaмoй севеpнoй зoнoй хлoпкoсеяния, пеpвoстепеннaя зaдaчa селекциoнеpoв выведение скopoспелых сopтoв с мaссoвым paскpытием кopoбoчек и высoкoй уpoжaйнoстью. Кaчествo вoлoкнa этo oчень вaжный пoкaзaтель для текстильнoй пpoмышленнoсти именнo этoт пoкaзaтель игpaет вaжную poль пpи пpoдaже вoлoкнa нa экспopт. Селекция тaкже нaпpaвление нa тaкие нaпpaвления кaк выведение устoйчивых сopтoв к зaбoлевaниям вилт, гoммoз, вpедителям хлoпкoвoй сoвки и кapaдpинa. Сopтa хлoпчaтникa, выведенные селекциoнеpaми ТOO «СХOС хлoпкoвoдствa и бaхчевoдствa» пpaктический все пpиспoсoблены к мехaнизиpoвaннoй paбoте, a тaкaже устoйчивы сpеднему зaсoлению
В статье представлены результаты 4-летних исследований (2018-2021 гг.) по возделыванию яровой тритикале при традиционном и органическом земледелии. Изучение технологий возделывания, повышающих продуктивность сельскохозяйственных культур являются актуальными во всем мире. Основными направлениями исследований это использование высокопродуктивных сортов, минеральных удобрений и пестицидов. Другим перспективным направлением является органическое земледелие, которое формирует у потребителей спрос на продукты питания, выращиваемых без использования минеральных удобрений и синтетических пестицидов. Целью исследования было определение влияния различных факторов на урожайность яровой тритикале возделываемой в условиях традиционного и органического земледелия. Опыты проводились в ТОО «НПЦЗХ им. А.И. Бараева» на черноземе южном. Яровую тритикале возделывали при традиционном и органическом земледелии с применением минеральных и органических удобрений. Из четырех лет проведения исследований только 2018 г. характеризовался благоприятными погодными условиями, остальные три года (2019-2021 гг.) были засушливые. Запасы продуктивной влаги в метровом слое почвы перед посевом в среднем за 2018-2021 гг. составили по традиционному земледелию –127 мм, по органическому – 130 мм и оценивались как удовлетворительные. За четыре года исследований в традиционном и органическом земледелии содержание в почве перед посевом N-NО3 (слой 0-40 см) оценивалось как высокое – 26,6-28,9 мг/кг, а Р2О5 (слой 0-20 см) соответствовало повышенной степени – 30,9- 41,6 мг/кг почвы. Стабильного влияния систем земледелия и доз удобрений на густоту стояния всходов не установлено. При традиционном земледелии урожайность тритикале в среднем по опыту составляла в 2018 г. – 3,10 т/га, в 2019 г. – 2,70, в 2020 г. – 1,82 и в 2021 г. – 1,70 т/га. В условиях органического земледелия за аналогичный период она была меньше на 38-42%. Корреляционный анализ выявил высокую положительную связь урожая зерна тритикале с содержанием продуктивной влаги в метровом слое почвы перед посевом (r = 0,83…0,98), с осадками июня (r = 56…92) и июня-августа (r = 0,47…0,92). Вместе с тем была получена высокая (>0,8) обратная зависимость урожая зерна со среднесуточной температурой августа.
Вид медоносной пчелы Apis mellifera разводится человеком с древнейших времен и обитает на всех материках, кроме Антарктиды, также имеет огромную хозяйственную ценность, собирая большие запасы меда и обеспечивая плановое опыление энтомофильных сельскохозяйственных культур.В последние годы изучение Казахстанских популяций пчел стало актуальным среди отечественных и зарубежных ученых. Задачами селекционно-племенной работы в пчеловодстве является сохранение и репродукция местных сложившихся во времени казахстанских популяций медоносных пчёл. Эта задача напрямую связана с защитой ареала обитания аборигенных пчёл, который ведет к научно обоснованному подходу к сохранению видов. Изучение особенности местных популяций, проведение генетической паспортизации казахстанских популяций - это основа для научно обоснованного ведения селекционного процесса. В статье были сравнены четыре различных протокола выделения ДНК на предмет их способности производить ДНК хорошего качества, чтобы найти подходящий метод, позволяющий извлекать высококачественную ДНК из материала Apis mellifera, который был бы пригоден для полимеразной цепной реакции (ПЦР) и дальнейших исследований генотипирования.Сранительная оценка методов выделения ДНК из пчел показала,что протокол №4 наиболее приемлемый по качеству полученной ДНК и по времени необходимого для выделения.
Бактериальный ожог является одной из наиболее вредоносных инфекционных болезней плодовых культур. В настоящее время он зарегистрирован более чем в 50 странах мира. Для многих стран, в том числе и для Казахстана, он является карантинным заболеванием. Экономический ущерб от бактериального ожога огромен и выражается не только в потере урожая и гибели деревьев, но и в затратах на выкорчевку и восстановление садов. Патоген длительное время может находиться в латентном состоянии и при наступлении благоприятных погодных условий быстро размножается и вызывает эпифитотийное развитие болезни. Учитывая, что бактериальный ожог является опасным карантинным заболеванием плодовых культур, необходимо было установить масштабы его распространения на юге и юговостоке республики в основных зонах промышленного садоводства. Для разработки конкретных защитных мероприятий необходимо провести анализ динамики бактериального ожога на яблоне в зависимости от фаз развития и складывающихся метеоусловий в течение вегетационного периода по годам исследований. Научная и практическая значимость проведённых исследований заключается в том, что результаты мониторинга бактериального ожога позволят обосновать объем проводимых карантинных и защитных мероприятий, точно установить сроки их проведения, а также они будут использованы при разработке прогноза развития болезни. При проведении исследований использовались общепринятые в карантине, фитопатологии и бактериологии методы, а также ПЦР анализ для идентификации возбудителя болезни. В результате мониторинга установлено, что очаги бактериального ожога встречаются во всех обследуемых областях юга и юго-востока республики в основных зонах промышленного плодоводства. Наибольшое количество их выявлено в Алматинской, меньше в Жамбылской и Туркестанской областях. Анализ сезонной динамики показал, что бактериальный ожог интенсивно развивается в первой половине вегетационного периода, следовательно, защитные мероприятия должны быть приурочены к этому периоду.
В статье рассматриваются вопросы агрохимического обследования почв сухостепной зоны Западно-Казахстанской области. В табличной и картографической форме приведены основные показатели плодородия почв: содержание гумуса, подвижных формы азота, фосфора, калия, серы и рН. В исследованных почвах содержание гумуса – низкое, обеспеченность нитратным азотом – повышенная и высокая, подвижным фосфором – от средней до высокой, подвижным калием – высокая, подвижной формы серы - от низкой до средней. Реакция почвенной среды – от нейтральной до слабощелочной. Рассмотрена методика использования цифровых инструментов при проведении агрохимического обследования полей. В качестве картографической основы использованы электронные карты с нанесенными на них контурами земельных участков, маршрутами и координатам точек отбора проб. Для получения, размещения и обмена информацией информационных и интерактивных услуг использовалась веб-портал Qoldau.kz. При обследовании объектов исследования использовались файлы с координатами полей в KML формате, в качестве программного обеспечения применялось приложение Offline Maps. Дана оценка почвенного плодородия и рекомендации по использованию агрохимических картограмм при внесении минеральных удобрений. При точечном внесении удобрений на участке с учетом картограмм нормы внесения могут значительно корректироваться.
Виды кормовых трав произрастающих в Казахстане – житняк и суданская трава. Житняк отличается способностью произрастать в засушливых регионах. Его особенностью является глубокая корневая система. Благодаря этим корням они растут в регионах с суровыми зимами и очень малым количеством осадков, а корни и растительные остатки обогащают почву органическими веществами.В связи с этим с целью изучения приемов ресурсосберегающей технологии и восстановление деградированных пастбищ для дальнейшего мелко-деляночного опыта были взяты сорт сорт люцерны «Туркестан 15», сорт суданской травы «Айлана 2017», сорт житняка «Карабалыкский 202» и биологические препараты «Плантобактерин» и «Тумат». По результатам фенологических наблюдений продолжительность межфазных периодов у злаковых трав с применением биопрепарата «Тумат» составляло 62-78 дней, а с прменением «Плантобактерин» 59-77 дней. В период бутонизации высота растений варианта, обработанного Туматом и Плантобактерином, составила 63,1-63,9 см, т.е. на 6,8-7,6 см выше контроля. Наибольшие урожайности отмечено в вариантах с применением биоудобрением «Плантобактерин» у люцерны 128/33,3 ц/га; суданской травы 200,7/48,6 ц/га и житняка 85,4/26,3 ц/га зеленой массы и сено. Применяемый биоудобрения «Плантобактерин» оказал существенное влияние на продуктивные показатели растений. Максимальный сбор кормовых единиц и переваримого протеина в 1 кг сухой массы составил у люцерны 0,70/11,8, что выше контроле на 0,13/1,187. При этом выход обменной энергии с гектара составил 10,4 ГДж/га.
Long-term research on monitoring of soil and climatic conditions of the Aral Sea region, based on screening of morpho-biological features in the context of zoned varieties and samples of local breeding, taking into account the complex of breeding and genetic parameters and practical breeding work, a model of a variety of spring barley was developed. The key basis of this model is the parameters aimed at creating precocious varieties with high salt and drought resistance. The formation of reproductive organs is completed before the onset of the summer drought. The purpose of the work is to increase the productivity of grain forage crops, launch new scientific and technical products on the market by creating fodder barley varieties resistant to environmental stress factors, competitive in productivity, grain quality when cultivated in environmentally unfavorable conditions of Kazakhstan. As a result of selection and practical work, five new varieties of spring barley adapted to stressful conditions were created: Sur Aruy, Inkar, Kaysar, Shakhristan, Altyn arai, combining a complex of productive traits and valuable biological properties. Varieties are included in the State Register of Breeding Achievements of the Kazakhstan Republic, and patents have been obtained
Елімізде құмай дақылы сияқты құрғақшылыққа төзімді, жоғары өнімді дақылдарды өндіру және оларды енгізу климаттың өзгеруі мен жауын-шашынның азаюына байланысты ең тиімді шешім болып табылады. Экологиялық-географиялық шығу тегі әртүрлі құмай генотиптерін экологиялық сорт сынау мал шаруашылығының ғана емес, сонымен қатар жеке шаруашылық жүргізуші субъект қызметінің басқа да бағыттарының экономикалық тиімділігін арттыруға қабілетті жемшөп өндірісіндегі тиімділігіжоғары бағыт болып табылады. Жасыл биомассаның жоғары өнімділігі және құмайдың құрғақшылыққа төзімділігі оларды Қазақстанның көптеген аумақтарында кеңінен өсіруге мүмкіндік береді. Зерттеу нысаны бойынша экологиялық-географиялық шығу тегі әртүрлі (Қазақстан, Ресей, Үндістан, Өзбекстан және басқа да елдер) құмайдың 225 генқорлары Қазақстанның оңтүстікшығыс аумағының суармалы жағдайында, батыс және солтүстік аумақтарының тәлімі жағдайдарында сыналды. Оңтүстік-шығыс Қазақстанның суармалы жағдайында гектарына 70 т астам, Батыс Қазақстанның тәлімі жағдайында гектарына 40 т дейін және Солтүстік Қазақстанның тәлімі жағдайында құмайдың көк балаусасы бойынша гектарына 50 тоннаға дейін өнімділік алуға болады, сонымен қатар құмай дақылдарын Қазақстанның көптеген аумақтарында өндіріске енгізіп, егістерінің кеңінен таралуына мүмкіндік береді.
В данной статье представлены результаты исследования влияния минеральных удобрений на содержание подвижных форм соединений меди, кадмия и цинка в почве. Применение минеральных удобрений важно для получения высоких урожаев сельскохозяйственных культур, но вместе с удобрениями в почву попадают и накапливаются тяжелые металлы, что приводит к накоплению их в почве. В 2020-2021 годах карбонатном Черноземе на севере Казахстана в ТОО «НПЦЗХ имени А.И. Бараева», изучалось многолетнее применение минеральных удобрений в стационарном опыте лаборатории агрохимии и удобрений. Микроэлементы изучались в двух качествах: валовое и подвижное содержание. Результаты исследования показали, что содержание валовых соединений кадмия и цинка превышало значения Кларка, но находилось в допустимых пределах для сельскохозяйственных земель, когда экологические показатели валового загрязнения учитывались с учетом токсичности. Обнаружено низкое содержание подвижных форм меди цинка и кадмия. Во всех вариантах опыта с традиционной и нулевой технологией наибольший процент подвижных форм микроэлементов от общего количества в почве был обнаружен для кадмия.
The article presents results of determining the content of proteins and amino acids in seeds of Kazakhstani soybean varieties. Soybean, being a high-protein crop, contains from 30 to 50% protein. The advantage of soybean protein among other plant proteins is the optimal ratio of amino acids. These are, first of all, essential amino acids, the main source of which are animal proteins. Soy protein, when consumed at the recommended dose, most fully satisfies the daily intake of essential amino acids of an adult. It is important to identify varieties with the highest protein content and essential amino acids. In this study, protein determination was carried out by the Bradford (1976) spectrophotometric method. The amino acid content was determined by high-performance liquid chromatography. The objects of the study were domestic soybean varieties: «Lastochka», «Almaty» and «Vita» from the collection of LLP «Kazakh Research Institute of Agriculture and Plant growing», Almalybak v., Almaty region, Republic of Kazakhstan. According to the results obtained, the Lastochka variety has the highest content of protein, and also the amino acid composition of the «Lastochka» variety differs by existing of essential amino acids, which makes it possible to recommend it both for food and in the production of biologically active additives.
The article presents calculations on the formation of a humidification contour during drip irrigation for intensive apple orchards, the location of drops is justified by conducting research with one, two, four drops for perennial apple trees growing on light gray soils in order to maintain humidity corresponding to 0.7 - 0.8 HB in conditions of insufficient natural moisture in in the foothill zone of the Zhambyl region, the intensity and time of operation of the water providing humidification. As apple trees grow and develop, the need to moisten the root layer along the drip line increases until the wet contours are completely covered. The establishment of the regularities of the process and dynamics of the formation of soil moisture, depending on the value of the irrigation rate during mass watering of apple orchards, has been established. Development of a mathematical model describing moisture exchange in the root layer of the soil during drip irrigation, and analytically solved the problem of moisture transfer, justified the parameters of the drip irrigation system using mathematical planning methods.
Изучение эффективности действия ионизирующих излучений на различных сортах риса, решение методических вопросов мутагенного воздействия их на растение риса, а также получение резистентных мутантов риса, как исходного материала для селекции сортов, адаптированных к стрессовым почвенно-климатическим условиям Казахстанского Приаралья является актуальным.В статье приведены материалы о проводимых исследованиях по изучению воздействия γ-лучей на различные сорта риса, с целью получения мутантных линий, устойчивых к факторам засоления (NaCl) и засухи (сорбит). Установлены средние летальные дозы гамма-лучей и средние летальные концентрации NaCl и сорбита, где наиболее четко проявляются мутагенное воздействие ионизирующих излучений и резистентность растений риса к фактором засоления и засухи. Установлено сортовое различие влияния ионизирующих излучений и стрессовых факторов на количество индуцированных резистентных мутантных форм допущенных к использованию сортов риса. При этом наибольшее количество растений, устойчивых к засолению и засухе получено у сорта Лидер, который в условиях Казахстанского Приаралья возделывается более длительное время (свыше 10 лет), чем вновь созданные сорта Сыр Сулуы и АйКерим (1-2 года).
The article presents the results of immunological evaluation of spring wheat samples with Lr genes for resistance to leaf rust. The purpose of the performed studies was the immunological evaluation and selection of sources of spring wheat resistance to leaf rust. The bjects of the study were samples of spring wheat from nurseries 6th ILRTN-15 and 18KASIB-LR-RES. Its scientific novelty consisted in the identification of effective Lr genes of resistance of spring wheat to the Kazakh population of leaf rust. Immunological studies were carried out in 2019-2020 in the conditions of the Kostanay region against a natural background of infection of wheat and in the conditions of the Almaty region against an artificially infectious background of infection of spring wheat. As a result of screening in the conditions of the regions of our study, 70 varieties and lines with effective Lr genes were identified as resistant. Thus, varieties and lines with Lr genes selected for leaf rust resistance are recommended by us as sources of resistance to the local leaf rust population.
Топырақ құнарлылығының маңызды көрсеткіштерінің бірі болып табылатын топырақтың электр өткізгіштігі (ЭӨ) кеңістікте және уақытта өте құбылмалы, әсіресе суармалы алқаптар топырағында. Бұл жұмыстың мақсаты Сырдария өзенінің бассейнінде топырақтың ЭӨ-н қолдана отырып, тұзданудың мезгілдік динамикасын зерттеу болды. Нәтижесінде ЭӨ-тің кеңістіктегі өзгергіштігі жоғары болғаны анықталды. Мәселені зерттеу үшін тәжірибе учаскелеріндегі топырақтардың тұздануына жылдың 3 мезгілінде бақылау жүргізіп, оның мезгілдік динамикасын анықтадық. Тұзданудың мезгілдік динамикасын бақылау барысында осы кеңістіктік таралған тұздардың жазғы сурару жұмыстарының әсерінен топырақтың 0-20 см және 20-50 см қабатындағы тұздар күзге қарай 50-100 см қабатына миграцияланатыны анықталды. Сондай-ақ, жалпы алғанда көктем мезгілінде тұздану қарқыны барлық қабаттарда басқа мезгілдермен салыстырғанда төмен болатыны анықталды. Далалық зерттеу жұмыстары кезінде алынған топырақтардың ЭӨ-гі туралы мәліметтер және топырақ үлгілерін химиялық талдау нәтижелері зерттеу нысанында тұзданудың барлық категориялары кездесетінін көрсетті. Жалпы алғанда, Отырар ауданындағы тұздану үрдісінің қарқындылығы – әртүрлі агроландшафттық бірліктерде бірдей дәрежеде жүрмейді және олар геоморфологиялық, гидрогеологиялық және географиялық орналасуына табиғи және антропогендік жағдайларға байланысты жүзеге асатыны анықталған.
В статье рассматриваются различные технологии, внедряемые в сельское хозяйство в процессе цифровой трансформации отрасли. Показаны возможности и перспективы таких технологий как интернет вещей (IoT), смарт-фермы, БПЛА, дистанционное зондирование. Данные технологии позволяют оптимизировать технологические процессы и управление, повысить производительность труда, снизить затраты, повысить конкурентоспособность отрасли, а также улучшить взаимодействие в цепочке производство-переработка-сбыт. Рассмотрены возможности и перспективы новейших концепций цифровизации АПК, таких как цифровые двойники ферм и Farming-as-a-Service. Показаны примеры внедряемых цифровых технологий в Казахстане. Принимая во внимание быстрое развитие и рост доступности цифровых технологий для Казахстана жизненно необходима модернизация сельскохозяйственной отрасли с внедрением самых современных технологий. Кроме того, актуальной задачей является создание условий для подготовки отечественных IT специалистов
Like many higher plant species, sucrose plays an important role in the growth of the sugar beet (Beta vulgaris L.). Sucrose is stored as the most important form of transport and storage of sugar in many plant species, especially plants with high economic value such as sugarcane, carrot, melon, tomato, and beet root. Sugar beet cultivation as a sugar crop in the eighteenth and nineteenth centuries through selection among fodder beets with considering morphological and physiological traits is a successful effort in plant breeding. At the beginning, the overall goal was to increase the sugar concentration to a suitable level for efficient processing and extraction while maintaining the yield level. Advances in this field intensified after the introduction of syrup concentration measurements and polarimetry machines. Following repeated selections, the sucrose content in sugar beet has risen from 6% to over 18% (fresh weight) in today’s hybrids. Improving the sugar yield per unit area was the foremost imperative goal of sugar beet breeding after promoting its cultivation. Recent advances in increasing the extraction coefficient of sugar confirm a promising future for this crop. In this chapter, the factors affecting the increase in sugar content in sugar beet, from the physiological and molecular aspects, are discussed.KeywordsSucrose accumulationSugar beetStorage root
Sixteen fenugreek landraces from Iran and two landraces from Egypt and India were evaluated for their biochemical and physiological responses to prolonged drought stress and recovery. The landraces were classified into six and three groups during drought stress and recovery, respectively, by cluster analysis. More tolerant landraces showed higher stomatal conductance and transpiration rate. The high potential recovery of landraces after rewatering can be related to high levels of SOD activity and proline accumulation. Ardabil and Shushtar landraces were the most drought tolerant landraces, while Shiraz exhibited the highest potential for recovery after drought. Varamin and Mashhad landraces were the weakest landraces during drought stress and recovery. Some Iranian landraces showed better responses to drought stress and recovery than exotic landraces. Our results indicated that high sensitivity to drought stress does not necessarily mean low recovery potential in landraces. Besides, wide genotypic variation in biochemical and physiological traits among the landraces indicates the importance of these traits in selecting for tolerance to drought stress, especially in arid and semi-arid environments.
In this study, we focus on the mitigation of the negative impact of drought using the application of superabsorbent polymers (SAPs) to seed. One way to monitor drought and quantify its impact on crops in field conditions is the nondestructive measurement of physiological processes of the crops using spectral indexes LAI and PRI during vegetation. Therefore, during 2018 and 2019, the increase in biomass and intensity of photosynthetic activity was monitored, and the effect of the SAPs application on the yield parameters of the sugar beet was evaluated in the trial conditions (control, SAPs) at the end of the vegetation period. Through statistical analysis, the significant impact (α ≤ 0.01) of SAPs application on the values of spectral indexes LAI and PRI as well as root and white sugar yields was found. Although the sugar content difference between SAPs and control conditions was not statistically significant, SAPs had a positive influence on the value of this parameter. It was found through periodic monitoring of spectral indexes during the growing period that the crop in the SAPs condition showed higher values of PRI at the beginning of vegetation, which was caused by the accumulation of moisture in the vicinity of the seed and subsequent faster growth of roots and photosynthetic apparatus. Moreover, the values of LAI were significantly higher (α ≤ 0.01) in the SAPs condition throughout the vegetation period. In the interaction evaluation, we confirmed that in both years the values of LAI were higher in the condition with SAPs compared with the control. In contrast, the PRI values were significantly different across conditions. The interaction of conditions with variety showed that the variety Brian obtained higher values of LAI and PRI in the SAPs condition. The correlation analysis found a positive correlation between spectral indexes LAI:PRI (r = 0.6184**), and between LAI:RY (r = 0.6715**), LAI:WSY (r = 0.5760**), and PRI:RY (r = 0.5038*), which confirms the close relationship between physiological processes in the plant and the size of its yield.
Drought stress deleteriously affects growth, development and productivity in plants. So, we examined the silicon effect (2 mmol) and proline (10 mmol) individually or the combination (Si + proline) in alleviating the harmful effect of drought on total phenolic compounds, reactive oxygen species (ROS), chlorophyll concentration and antioxidant enzymes as well as yield parameters of drought-stressed sugar beet plants during 2018/2019 and 2019/2020 seasons. Our findings indicated that the root diameter and length (cm), root and shoot fresh weights (g plant−1) as well as root and sugar yield significantly decreased in sugar beet plants under drought. Relative water content (RWC), nitrogen (N), phosphorus (P) and potassium (K) contents and chlorophyll (Chl) concentration considerably reduced in stressed sugar beet plants that compared with control in both seasons. Nonetheless, lipid peroxidation (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2) and superoxide (O2●−) considerably elevated as signals of drought. Drought-stressed sugar beet plants showed an increase in proline accumulation, total phenolic compounds and up-regulation of antioxidant enzymes catalase (CAT) and superoxide dismutase (SOD) activity to mitigate drought effects. Si and proline individually or the combination Si + proline considerably increased root and sugar yield, sucrose%, Chl concentration and RWC, MDA and EL were remarkably reduced. The treatments led to adjust proline and total phenolic compounds as well as CAT and SOD activity in stressed sugar beet plants. We concluded that application of Si + proline under drought stress led to improve the resistance of sugar beet by regulating of proline, antioxidant enzymes, phenolic compounds and improving RWC, Chl concentration and Nitrogen, Phosphorus and Potassium (NPK) contents as well as yield parameters.
Sugar beet is a biennial crop, but the storage root used for sugar manufacture is formed in the first year. Development of leaf canopy and storage root is temperature driven and not separated by distinct growth stages. Most critical stages are emergence, plant establishment, and early development. Breeding has shifted assimilate partitioning towards sugar storage at the expense of leaf mass and beet structural compounds. As yield formation is sink-limited most of the growing season, factors affecting radiation interception (decreasing radiation and canopy cover in autumn, elevated CO2, N supply) have less effect on yield, whilst genotypic yield is stable in different environments. Consequently the correlation between yield and canopy cover is loose, and nutrient demand increases only slightly with increasing yield. Despite high water use efficiency (yield per unit evapotranspiration), an adequate water supply is demanding for high yielding crops. As sugar beet has already a high yield potential, closing the yield gap will be an important challenge in future.
Chinese cabbage (Brassica campestris L. ssp. pekinensis) is a widely cultivated vegetable crop in eastern Asia. The flavor of Chinese cabbage was mostly affected by soluble sugar content. To make clear its accumulation and regulation mechanism, the content of different sugars in the internal blade (IB), the internal midrib (IM), the external blade (EB) and the external midrib (EM) of the leafy head were determined during the leafy head formation. The results showed that fructose was the major sugar accumulated in the internal tissues, followed by glucose. IM was the main tissue of sugar accumulation with the highest contents of total soluble sugar and hexose at harvest. RNA sequencing data of the four tissues at 90 DAS showed that the number of differentially expressed genes (DEGs) in IB and IM was the least (2408), while the number of DEGs between the external and internal tissues ranged from 6037 to 8674. The enzyme genes differentially expressed in ‘starch and sucrose metabolism’ pathway was detected during the leafy head development. The expression of two sucrose synthase (SUS) genes, SUS1a (Bra002332) and SUS1b (Bra006587), were always higher in IM than in the other tissues, and positively correlated with the content of total soluble sugar and hexose, respectively. SUS1 was considered to play an important role in leafy head development and sugar accumulation in Chinese cabbage.
Effects on sugar beet (Beta vulgaris L.) of current and elevated CO2 and temperature alone and in combination and their interactions with abundant and deficient nitrogen supply (HN and LN, respectively) have been studied in three experiments in 1993, 1994 and 1995. Averaged over all experiments, elevated CO2 (600 μmol mol–1 in 1993 and 700 μmol mol–1 in 1994 and 1995) increased total dry mass at final harvest by 21% (95% confidence interval (CI) = 21, 22) and 11% (CI = 6, 15) and root dry mass by 26% (CI = 19, 32) and 12% (CI = 6, 18) for HN and LN plants, respectively. Warmer temperature decreased total dry mass by 11% (CI = – 15, – 7) and 9% (CI = – 15, – 5) and root dry mass by 7% (CI = – 12, – 2) and 7% (CI = – 10, 0) for HN and LN plants, respectively. There was no significant interaction between temperature and CO2 on total or root dry mass. Neither elevated CO2 nor temperature significantly affected sucrose concentration per unit root dry mass. Concentrations of glycinebetaine and of amino acids, measured as -amino-N, decreased in elevated CO2 in both N applications; glycinebetaine by 13% (CI = – 21, – 5) and 16% (CI = – 24, – 8) and -amino-N by 24% (CI = – 36, – 11) and 16% (CI = – 26, – 5) for HN and LN, respectively. Warmer temperature increased -amino-N, by 76% (CI = 50, 107) for HN and 21% (CI = 7, 36) for LN plants, but not glycinebetaine.
A recent study showed that drought stress was the major factor causing yield loss of the sugar beet crop in the UK. That study has been extended here by modelling potential and rain-fed yields (1961–1995) for European areas where irrigation of sugar beet is uncommon. The inputs to this study are an improved crop growth model, the European monthly half-degree gridded meteorological data time series, and a map of soil texture and available water capacity in sugar beet growing regions. Model outputs were scaled using a ratio of national mean to experimental plot yields to reflect commercial performance of a hypothetical 1998 variety for all years. The model was run on daily weather data reconstructed from monthly values. Potential yields increased from north to south and from west to east due to increased radiation receipts. Drought losses were greatest in east Ukraine and southern Russia, at over 40% of potential yield (5 t ha−1). Losses were intermediate (15–30% or about 2 t ha−1) in central Ukraine, west Poland, east Germany and England (sandy soils) and lowest in NW Europe and west Ukraine. Increasing continentality decreases the number of rainy days per month during summer and the fraction of diffuse radiation; this reduces the radiation use efficiency by as much as 11%. Model output was also used to examine the efficiency of sugar beet production across Europe; at the extremes, NW European farmers deliver about 80% of the potential rain-fed yield while Polish farmers are only able to deliver 40%. This study demonstrates the importance of breeding for drought stress tolerance in Europe.
Persistently sub-optimal environmental conditions constitute stress. Perception and signaling lead to protein expression changes, the activation of new biochemical pathways, and repression of others which are characteristic of the unstressed state. Protective metabolic adaptations alter physiological reactions of the whole plant. Paramount among the mechanisms are oxygen radical scavenging, maintenance of ion uptake and water balance, and reactions altering carbon and nitrogen allocation, such that reducing power is defused. Elements of the stress signaling pathways and proteins that lead to stress protection have recently become known.
To investigate the factors governing the accumulation of sucrose and amino acids in the taproots of sugar beet, their contents
were measured in the leaves, phloem sap and the taproots of sugar beet, fodder beet and a hybrid between both, grown on either
3.0 or 0.5 mM nitrate. In the taproots the contents of malate, citrate and inorganic ions were also determined. For the high
sucrose accumulation in sugar beet as compared to the other varieties three factors were found. (a) In sugar beet, less amino
acids and more sucrose are taken up into the phloem than in fodder beet. (b) In sugar beet, the sucrose and amino acid syntheses
are less sensitive to the nitrate concentrations that are required for optimal plant growth than in other varieties. In fodder
beet, upon raising the nitrate concentration from 0.5 mM to 3 mM, the synthesis and storage of sucrose is decreased and that
of amino acids increased. The corresponding values in sugar beet (0.5 mM) are similar to those in fodder beet and are not
much affected by an increase of nitrate. (c) The sucrose accumulation is limited by the accumulation of inorganic ions in
the taproots. The sucrose content in the taproots is negatively correlated to the total ion content. Whereas sucrose represents
two-third of all solutes in the taproots of sugar beet, it amounts to only one-third of the solutes in fodder beet taproots.
The role of the demand for carbon assimilates (the ‘sink’) in regulating photosynthetic carbon assimilation (Pn: the ‘source’) in response to phosphate (Pi) deficiency was examined in tobacco (Nicotiana tabacum L.). Pi supply was maintained or withdrawn from plants, and in both treatments the source/sink ratio was decreased in some plants
by darkening all but two source leaves (partially darkened plants). The remaining plants were kept fully illuminated. Pi‐sufficient plants showed little variation in rate of Pn, amounts of Pi or phosphorylated intermediates. Withdrawal of Pi decreased Pn by 75% under the growing conditions and at both low and high internal CO2 concentration. Concomitantly, Pi, phosphorylated intermediates and ATP contents decreased and starch increased. RuBP and activity of phosphoribulokinase closely
matched the changes in Pn, but Rubisco activity remained high. Partial darkening Pi‐deficient plants delayed the loss of photosynthetic activity; Rubisco and phosphoribulokinase activities and amounts of sucrose
and metabolites, particularly RuBP and G6P, were higher than in fully illuminated Pi‐deficient plants. Rates of sucrose export
from leaves were more than 2‐fold greater than in fully illuminated Pi‐deficient plants. Greater sucrose synthesis, facilitated by increased G6P content, an activator of SPS, would recycle Pi from the cytosol back to the chloroplast, maintaining ATP, RuBP and hence Pn. It is concluded that low sink strength imposes the primary limitation on photosynthesis in Pi‐deficient plants which restricts sucrose export and sucrose synthesis imposing an end‐product synthesis limitation of photosynthesis.
Osmolyte accumulation (OA) is frequently cited as a key putative mechanism for increasing yields of crops subjected to drought conditions. The hypothesis is that OA results in a number of benefits that sustain cell and tissue activity under water-deficit conditions. It has been proposed as an effective tolerance mechanism for water deficits, which could be enhanced in crops by traditional plant breeding, marker-assisted selection or genetic engineering, to generate drought-tolerant crops. However, field studies examining the association between OA and crop yield have tended to show no consistent benefit. The few, often-cited, investigations with positive associations were obtained under severe water deficits with extremely low yields or conditions with special water-supply scenarios when much of the benefit is plant survival. Under conditions where water deficits threaten crop survival, yields are so low that even large fractional yield gains offer little practical benefit to growers. Indeed, the often-cited benefit of turgor maintenance in cells is likely to result in crop behaviour that is exactly opposite to what is beneficial to crops. The one clear mechanism identified in this review for beneficial yield responses to OA is in the maintenance of root development in order to reach water that may be available deeper in the soil profile.
Stable carbon isotope discrimination (Δ13C), photosynthetic performance (A), dry matter accumulation (DW), and sucrose yield (Ys) of sugar beet were evaluated in a glasshouse experiment under transient (TS) and permanent (PS) water stress. A was significantly reduced under drought, to an extent depending on stress duration. The reduced A was strictly associated with a low DW and Ys, the later being 42% lower in PS than control plants (C). Restoring water steeply increased A and the associated leaf traits (RWC, leaf water potential etc.), but the increase of Ys was negligible. Therefore, the negative effects of severe water stress in the early growth period, though reversible on gas-exchange
and most leaf traits, can drastically reduce Ys of sugar beet. Furthermore, A seems not to be effective in predicting sucrose accumulation, although it was very effective in detecting the occurrence
of plant water stress. The A/Ci model was used to assess the photosynthetic adjustments to continuous or transient drought by calculating the photosynthetic
parameters Vcmax and Jmax and then compared with Δ13C. Mesophyll conductance (gm) was estimated by comparing Δ13C measured on soluble sugars and gas-exchange data. This approach confirmed the expectation that gm was limiting A and that there was a significant drop in [CO2] from the substomatal cavities and the chloroplast stroma both in favourable and drought conditions. Therefore, the carbon
concentration at the carboxylation site was overestimated by 25–35% by conventional gas-exchange measurements, and Vcmax was consistently underestimated when gm was not taken into account, especially under severe drought. Root Δ13C was found to be strictly related to sucrose content (brix%), Ys and root dry weight, and this was especially clear when Δ13C was measured on bulk dry matter. By contrast, leaf Δ13C measured in soluble sugars (Δs) and bulk dry matter (Δdm) were found to correlate weakly to brix% and yield, and this was not surprising as the integration time-scale of leaf Δs and Δdm were found to be shorter than that of root Δ13C in bulk dry matter. The effect of water stress on diffusive and biochemical limitations with different integration times
ranged from 1 d (leaf Δs) to more than 1 month (root Δdm).
Sink tissues that store osmotically active compounds must osmoregulate to prevent excessively high turgor. The ability to regulate turgor may be related to membrane transport of solutes and thus sink strength. To study this possibility, the kinetics of sugar uptake were determined in sugar beet (Beta vulgaris L.) taproot tissue discs over a range of cell turgors. Sucrose uptake followed biphasic kinetics with a high affinity saturating component below 20 millimolar and a low affinity linear component at higher concentrations. Glucose uptake exhibited only simple saturation type kinetics. The high affinity saturating component of sucrose and glucose uptake was inhibited by increasing cell turgor (decreasing external mannitol concentrations). The inhibition was evident as a decrease in V(max) but no effect on K(m). Sucrose uptake by tissue equilibrated in dilute buffer exhibited no saturating component. Ethylene glycol, a permeant osmoticum, had no effect on uptake kinetics, suggesting that the effect was due to changes in cell turgor and not due to decreased water potential per se. p-(Chloromercuri)benzene sulfonic acid (PCMBS) inhibited sucrose uptake at low but not high cell turgor. High cell turgor caused the tissue to become generally leaky to potassium, sucrose, amino acids, and reducing sugars. PCMBS had no effect on sucrose leakage, an indication that the turgor-induced leakage of sucrose was not via back flow through the carrier. The ability of the tissue to acidify the external media was turgor dependent with an optimum at 300 kilopascals. Acidification was sharply reduced at cell turgors above or below the optimum. The results suggest that the secondary transport of sucrose is reduced at high turgor as a result of inhibition of the plasma membrane ATPase. This inhibition of ATPase activity would explain the reduced V(max) and leakiness to low molecular weight solutes. Cell turgor is an important regulator of sucrose uptake in this tissue and thus may be an important determinant of sink strength in tissues that store sucrose.
A recent study showed that drought stress was the major factor causing sugar yield loss of the sugarbeet crop in the UK. That study has been extended here by modeling potential and rain-fed yields (1961-1995) for European areas where irrigation of sugar-beet is uncommon. The model was also used to examine the efficiency of sugarbeet production across Europe. The impact of future climate change on sugarbeet yields is assessed over western Europe using future (2021-50) climate scenario data from a General Circulation Model (GCM) and the Broom's Barn simulation model of rain-fed crop growth and yield. Yield increases due to future climate change are expected in northern Europe of around 1 t/ha of sugar for 2021-50 but decreases of similar magnitude in northern France, Belgium and west/central Poland, despite accelerated growth in warmer springs. Drought losses are expected to approximately double in areas with an existing problem and to become a serious new problem in NE France and Belgium. The annual variability of yield will also increase by half. These changes are independent of the 10% yield increase expected as a direct effect of the increase in atmospheric CO 2 concentration.
Nitrogen fertilizer applied to sugar-beet increased plant and root dry weight and leaf area, and decreased the sugar content of the roots per cent of both fresh and dry weight. Change in leaf area accounted wholly for the increase in plant dry weight produced by nitrogen, because net assimilation rate was unaffected. Nitrogen did not alter the partition of the total assimilate between roots and shoots, but increased the fraction of total assimilate entering the roots that was used in growth, at the expense of that stored as sugar. Thus, plants with more nitrogen had a smaller proportion of their root dry weight as sugar because more was metabolized in growth of the roots, and not because less entered the roots.
The heavier roots of plants given more nitrogen were larger in cross-sectional area because the areas of both parenchyma and vascular zones of each peripheral ring within the root were larger; the number of rings was not increased. Nitrogen increased the areas of the tissues in these zones by enlarging cell volumes, not by increasing the number of cells within the tissues. Increase in cell volume was accompanied by proportional increases in the weights of non-sugar dry matter per cell and water per cell, but the amount of sugar per cell was proportional to cell volume only during the initial stage of cell expansion up to cell volumes of about 15×10⁻⁸ cm²; thereafter it was less than proportional, so that sugar per cent of both fresh and dry weight decreased as cell size increased beyond 15×10⁻⁸ cm². The relation of sugar per cell to cell volume was the same with both amounts of nitrogen given. This implies that increase in nitrogen supply made the sugar concentration of the root less by increasing the size of the root cells and not by a specific effect on sugar storage.
Clearing 1-5-mm-thick cross sections of growing storage roots indicated that number and development of vascular rings in the storage root are consequences of the increasing number of leaves. The vascular bundle rings are originally spirals derived from the spiral arrangement of leaves. The new clearing method also revealed that leaf traces can traverse each other in the stem without forming many vascular connections. Inversion of the vasculature, e.g., traces from peripheral leaves extending to the root center and traces from young leaves extending to the root periphery, takes place within the stem and also partly in the hypocotyl. Evidence is provided that (1) each vascular ring is in direct connection with a certain number of leaves, and (2) leaves are preferentially connected with regions of the root belonging to the same orthostichon. Our results support the hypothesis of a structural congruence in the development of leaves and of the storage root.
Using serial sections and cinematography, we studied vascular and successive cambial development and activity in sugarbeet plants grown in the phytotron and outdoors. Except for the first two leaves, which gave fewer veins, each leaf petiole has three major and several minor veins. Every leaf induces the formation of at least two cambial rings, eventually becoming directly connected with their secondary vascular tissues. The first cambium originates from procambium and interfascicular parenchyma, as in plants with one cambium. Fascicular cambia, which develop within traces of ca. four leaves, differentiate into one ring during the early stage of growth. Such a correlation was not found in mature beets. The leaf traces run across the stem to the periphery of the pith, anastomosing into different rings. All traces weave into a complicated network in the upper part of the hypocotyl, passing downward around the disintegrating pith and continuing into the rings of the root. In the root, a second cambium ring develops in the phloem parenchyma inside the endodermis. Each successive cambial ring differentiates in the outer parenchyma derivative already formed by a previous cambium. Radial connections between strands of adjacent rings and tangential connections between strands of the same ring are common. Cambia of successive rings are active simultaneously, each ring producing xylem and phloem at the beginning but mainly phloem later.
We tested four hypotheses for the control of partitioning of photoassimilated C-11 between the two halves of split root systems
of young barley plants. Our data supported the hypothesis that phloem is unloaded without the use of metabolic energy, since
several metabolic inhibitors applied to one half of a split root system reduced respiratory oxygen uptake without altering
import of C-11. The hypothesis that rate of import C-11 is directly related to metabolic activity in the root was rejected,
since (a) certain inhibitors reduced respiration but not import and (b) exogenous sucrose reduced import into the root half
to which it was supplied. Our data were consistent with the hypothesis that import is related to the total ability (metabolism
plus storage) of the sink to use sucrose. Treatments that would have led to greatly decreased use of sucrose (iodoacetate
inhibition) decreased import before those which would have led to a smaller decrease in sucrose use (FCCP inhibition). These
data, and the reduction in import to a root half supplied exogenously with sucrose, supported the hypothesis that the size
of soluble sugar pools within the roots is, in the short-term, inversely proportional to rate of import, the soluble sugar
pools thus acting as a mediator between rate of sucrose use and supply from the phloem.
Osmotic adjustment (erroneously called 'osmoregulation') is generally regarded as an important adaptation to drought or salinity. Because it helps to maintain turgor and cell volume, it is often thought to promote growth, yield, or survival, of plants in dry or saline soils. However, a physiological rationale for such views is lacking. Osmotic adjustment itself cannot promote growth; the solutes which account for it must be diverted from essential processes such as protein and cell wall synthesis. Further, it now appears that turgor does not control cell expansion or stomatal conductance. Thus, osmotic adjustment cannot affect yields except via other processes, the controls of which are almost entirely unexplored. Future research in this area should test hypotheses, rather than merely measure osmotic adjustment.
Drought stress and virus yellows disease are two of the major problems of sugarbeet crop production in the UK. We have calculated the annual national drought losses from 1980 to 1995 by using long term data sets for two sites (IACR-Broom's Barn, Suffolk and ADAS Gleadthorpe, Nottinghamshire) to relate yield loss to cumulative potential summer moisture deficit, and combining these relationships with regional meteorological records, soil type and crop distribution data.
Experimentally measured relationships between yield losses and the timing of virus yellows infection were combined with annual survey data of the extent of the problem, and calculated infection dates from the UK aphid suction trap network, to calculate actual national annual losses to the disease. Potential losses in the absence of control measures were then calculated by use of data from trials and surveys of pesticide use.
The results showed a mean annual loss of production to drought stress of 141000 t/year of sugar, 10·5% of production, with a loss to the industry of £27·9 million. Losses in individual years varied from zero to 2·5 times the mean figure. Actual losses to virus yellows were much smaller, due to the efficacy of treatments, averaging 24700 t/year of sugar (1·8% of national yield, financial loss £5·5 million). Average potential virus yellows losses in the absence of control measures were approximately double this.
Control of virus yellows is a major, cost-effective contributor to rising and consistent sugarbeet production. Nationally, irrigation has made little impact on drought losses and, due to constraints in surface water supply, this situation appears likely to continue. Improved drought stress tolerance represents the largest single opportunity for yield and profitability improvement of the sugarbeet crop in the UK at present. Predicted climate change appears likely to increase the severity of both drought and disease stresses. Drought stress appears relatively less important in other NW European sugarbeet-growing areas.
Moderate drought stress increases the root-to-shoot ratio in sugar-beet plants. The question arises whether abscisic acid occurs in these plants and whether it plays a role in their adaptation to limited water supply. Thus, after identification by GC/MS, the content of free ABA and its alkaline hydrolysable conjugates was determined by capillary GLC in sugar-beet plants of pot and field experiments with differentiated water supply. It was shown that leaves had a higher content of free ABA than tap roots. Within the leaf apparatus the young organs contained more ABA than the fully developed leaves. Moderate drought stress increased both free and alkaline hydrolysable ABA contents in leaves of intact plants, whereas the ABA content of tap roots was not demonstrably influenced. In contrast, severe and rapid osmotic stress treatment of detached leaves by dipping the petioles in mannitol solutions increased the free ABA content at the expense of the hydrolysable conjugates. This suggests an ABA release by the latter. Therefore, sugar-beet plants seem to have two mechanisms for increasing the free ABA content under drought stress conditions: the gradual synthesis of ABA including its conjugates and the release of free ABA from ABA conjugates.
In a pot experiment sugar beet Beta vulgaris L. ssp. vulgaris, cv. Kawetina, was grown on alluvial soil (21 mg exchangeable K 100 g−1) containing 0 (K1), 20 (K2), 40 (K3) and 60mg fertiliser K 100 g−1 soil (K4). The plants were sown on 15 March 1983 and harvested on 23 June, 14 July and 30 August 1983. At final harvest root dry weight/plant had reached 269 g in K1 and between 304 and 310 g in K2-K4. Sucrose values were 15% (K1) and 17.3–17.7% of root fresh weight (K2-K4) respectively. The osmotic potential of the storage root decreased with increasing K nutrition and time. At final harvest ψ, was between −1.83 (K1) and −2.26 MPa (K4), 75–79% thereof being contributed by sucrose. Sucrose concentrations in press sap increased from 340–400 mM on 23 June to 475 (K1) and 540–570 mM (K2-K4) at the end of August. In the same period K concentrations declined from 40–100 to 10–35 mM K+. The sucrose, K and Mg concentrations measured in the press sap were lower than those calculated from sucrose, K, Mg and moisture content of the storage root. This indicates that press sap from thawed storage root tissue is not fully representative. Betaine, analysed only at final harvest, significantly increased with increasing K concentrations in the storage root (r=0.83) and a significant linear regression was found between betaine and sucrose accumulation (r=0.57). This is consistent with the role of betaine as a cytosolic osmoticum for sugar beet storage tissue. Other solutes in the cytosol may also contribute to osmoregulation as sucrose accumulates in the vacuoles.
SUMMARYA study was made of the growth of the storage root of sugar beet as a sugar accumulating organ. The storage root grew by simultaneous cell multiplication and expansion from a series of peripheral secondary meristems laid down during the early stages of development. The weight of water and of non-sugar dry matter per cell increased in proportion to the increase in cell volume. The amount of sugar per cell was proportional to cell volume only during the initial stage of cell expansion up to volumes of about 15 times 10-8 cm3; thereafter it was less proportional. Thus, average cell size is a major determinant of the sugar concentration of the storage root. The implications of this are discussed.
The chemical composition of sugar beet is the most important parameter affecting its processing. Sugar factories require beet with high concentrations of sucrose and low concentrations of melassigenic substances to maximise the amount of extractable sugar. In order to plan the processing campaign, forecasts of root and sugar yield by prediction models are possible but there are no means to predict the technical quality of the beet. In the present study, the seasonal development and physiological relationships of different parameters of sugar beet quality were analysed. In order to estimate possibilities for quality forecasts, the concentrations of beet quality variables in October were correlated with corresponding quality measurements in late summer and to weather variables during the growing season by linear regressions. In 2000 and 2001, 27 field trials were conducted on commercial farm fields in all sugar beet growing areas in Germany. From June to October, sequential samples were taken every 4 weeks and the concentrations of sucrose, potassium, sodium, total soluble nitrogen, α-amino nitrogen, nitrate, betaine, reducing sugars and marc in the beet were determined. The sucrose concentration increased progressively until the final harvest date in autumn, whereas the concentrations of the melassigenic substances decreased markedly until late summer and remained fairly constant as the season progressed. Marc concentration was the most stable of the parameters analysed. The sucrose concentration was positively correlated with the concentrations of dry matter, betaine and marc, but negatively with nitrate concentration and leaf yield throughout the season. The correlation between the concentrations of sucrose and nitrogenous compounds measured in summer and their final concentrations in autumn was rather weak. However, it was close for potassium, sodium and marc and a satisfactory prediction of their final concentrations was possible by the end of August. Based on weather data, beet quality was not predictable. Therefore, it seems to be difficult to integrate beet quality parameters into prediction models. Copyright © 2005 Society of Chemical Industry
Depending on genotype, sugar beet can differ considerably in yield and quality characteristics. These are additionally modified by environmental conditions with drought stress recently gaining in importance, restricting growth and altering the chemical composition of the beet. The occurrence and development of these genotypic differences during the vegetation period and their possible interaction with environmental conditions were investigated. In 2002 and 2003, four sugar beet genotypes differing in yield and quality and putative different with regard to drought tolerance were tested in field trials, partly under irrigated conditions, in a total of 10 environments with consecutive harvests starting in early summer. In 2 years of stress and non-stress conditions they exhibited significant differences for taproot and leaf dry matter and the concentration of sucrose, K, Na and α-amino nitrogen in the taproot. These differences existed already in mid-June and virtually did not change any more from this time on. Accordingly, interactions between genotype and harvest date did not occur. For sugar beet, genotype by environment interactions generally do not exist. Water supply, as an important single determinant of the effect of the environment, was studied separately analysing data from selected locations. Under drought conditions, withholding irrigation reduced leaf and taproot growth and root-to-leaf ratio, decreased the percentage of sucrose in dry matter and resulted in an accumulation of α-amino N. Interactions between genotype and water supply did not occur for any of the parameters under study. A genotype-specific high α-amino N content, which might be of advantage for osmoregulation, did not improve the adaptation to drought. Differences in leaf maintenance or taproot-to-leaf ratio during drought also did not affect yield response. Due to the lack of interaction between genotype and harvest date as well as between genotype and irrigation it is concluded that harvest date or climatic factors of the growing region do not have to be taken into consideration when choosing a variety.
Adaptation to low water availability in sugar beet includes the accumulation of solutes relevant for the technical quality of the beet. Two sugar beet genotypes were grown in pot experiments under drought stress of different severity to study effects on taproot composition and concentration of solutes relevant for technical quality, reversibility of drought effects after re-watering and genotypic differences in drought response. Differences in stress sensitivity between the genotypes were not observed as reductions in taproot and leaf dry weight and white sugar yield were the same. Increasing dry matter concentration with decreasing water supply could, in part, be attributed to an increase in the concentration of cell wall components. The major solutes in the taproot were sucrose, potassium, amino N (the sum of amino acids) and betaine. Sucrose concentration decreased considerably under drought, indicating limited availability of assimilates. In contrast, all further solutes increased in concentration with increasing severity of stress. However, the response of individual solutes varied largely. Changes in amino N and nitrate were most pronounced and probably reflect accumulation of non-utilized metabolites under limited growth. The drought-induced accumulation of taproot solutes implicates a considerable decrease in the technical quality of the beet. It was only in part reversible by re-watering. Genotypic variability for solute accumulation under water deficiency was observed but was not linked to drought tolerance.
The responses of two sugar beet genotypes, 24367 (putative droughttolerant) and N6 (putative drought intolerant), to drought and nutrientdeficiency stress were investigated in an attempt to identify reliable andsensitive indicators of stress tolerance. In glasshouse-grown plants of bothgenotypes, relative water content (RWC) of the leaves decreased and leaftemperature increased in response to drought stress. Genotype differences inresponse to drought included leaf RWC, glycine betaine accumulation, alterationof shoot/root ratio and production of fibrous roots. Thus, in comparison to N6,genotype 24367 lost less water from leaves, produced more fibrous roots,produced more glycine betaine in shoots and tap roots and had a much reducedshoot/root ratio in response to withholding water for up to 215 h.The hydraulic conductance and sap flow of sugar beet seedlings grown innutrientculture decreased when subjected to nitrogen deficiency stress. Under nitrogensufficient conditions sap flow was greater in 24367 than in N6. The resultsindicate that genotype 24367 is more tolerant to stresses induced by water andnitrogen deficiency and that increased fibrous root development may be a majorfactor in increasing sap flow via a concomitant enhancement of aquaporinactivity.
Improvements in drought tolerance of crop plants require research focused on physiological processes. In 2002 and 2003 pot experiments with sugar beet were conducted in a greenhouse. Two (2002) or three (2003) different genotypes were subjected to three watering regimes (100, 50 and 20% of water holding capacity). Gas exchange, chlorophyll fluorescence and water-use efficiency (WUE) as parameters of possible relevance for drought stress tolerance in sugar beet were investigated. It was studied whether 13C discrimination (Δ) is suitable as an indirect measure for WUE of sugar beet.DM yield, photosynthesis rate, transpiration rate and stomatal conductance decreased with increasing severity of drought stress. In contrast, internal CO2 partial pressure remained relatively stable and effective quantum yield of photosynthesis was reduced only under severe drought, which points at non-stomatal inhibition of photosynthesis. Different sugar beet genotypes showed significant differences in DM yield, but interactions between genotype and water supply did not occur, indicating that genotypic differences in drought tolerance did not exist. In accordance with that, drought-sensitivity of gas exchange and chlorophyll fluorescence was the same in different genotypes. Δ was higher in the leaves than in the taproot. Reductions in Δ in drought-stressed plants corresponded to about 24% higher WUE. Differentiating between plant organs, only leaf Δ was negatively correlated with WUEL whereas taproot Δ and WUET were unrelated. Δ was therefore proven to be a sensitive indicator for water availability during the growing period. However, similar as other parameters relevant for drought stress tolerance it requires investigations in broader genetic material of sugar beet to detect genotypic differences.
In Germany, from March to September precipitation in 2003 was only 57% of that in 2002. Despite visible symptoms of drought stress, beet yield and white sugar yield were similar in both years. Similar growth under conditions of reduced precipitation pointed to an adaptation by accumulation of solutes. We therefore investigated changes in the concentration of major solutes in different organs (beet, crown, young and mature leaf petioles and blades) of sugar beet in response to low precipitation as a possible explanation for sustained plant growth. In three field trials, sugar beet was harvested at three time points from 100 to 170 days after sowing.The response to low precipitation differed in the different organs, both in magnitude and in the type of solutes involved. Despite considerable changes in the concentrations of single solutes in all organs, the sum of solutes was significantly affected by the year only in beet, crown and mature petioles. In the beet, the concentration increased in the dry year, whereas in crown and mature petioles it decreased. The beet accumulated 156% more glutamine, 72% more amino N, and 57% more betaine in 2003 than 2002, concentrations of fructose and glucose were increased by 44 and 42%, and of sucrose by 5%. The accumulation of glutamine, glucose and fructose was specific to the beet, in the other organs their concentrations were decreased. Specific activity of glutamine synthetase was 68% higher in 2003 than 2002 in the mature blades, thus being a possible source of glutamine in the beet. Another source may have been protein degradation since a net loss of protein occurred in all organs. This accumulation of solutes in the beet may have contributed to achieve osmotic adaptation and to sustain beet growth under conditions of low precipitation, however, it led to a decrease in the technical quality of sugar beet.
Sugar beet (Beta vulgaris ssp. altissima Döll) was grown in the field under free-air CO(2) enrichment (FACE, 550 ppm) and different nitrogen (N) supply (2001: 126 (N100) and 63 kg.ha(-1) (N50); 2004: 156 (N100) and 75 kg.ha(-1)) during two crop rotations. Canopy CO(2) exchange rates (CCER) were measured during the main growth phase (leaf area index > or =2) using a dynamic chamber system. Canopy CO(2) exchange data were analysed with respect to treatment effects on seasonal means and light use efficiency and light response characteristics. CO(2) enrichment enhanced CCER throughout the season. However, in both years, CCER declined after the second half of August independent of radiation and [CO(2)]. Elevated [CO(2)] strongly stimulated CCER on a seasonal basis, whereas the reduction of CCER caused by low N was below 10% and not significant. There were no effects of N on daily radiation use efficiency of carbon gain calculated from CCER data, but a strong enhancement by CO(2) enrichment. CCER closely tracked diurnal variations in incident photosynthetic photon flux density (PPFD, mumol.m(-2).s(-1)). The relationship between CCER and incident PPFD was curvilinear. In both seasons, initial slopes and maximum rates (CCER(max)) were determined from two 6-day periods using these relationships. The first period was measured after canopy closure (first half of July) and the second in the second half of August. In the first period, elevated [CO(2)] increased the initial slopes. Low N supply affected neither the initial slopes nor their response to elevated [CO(2)] in either period. In contrast to initial slopes, N stress limited the [CO(2)] response of CCER(max) in the first period. In the second period, however, this interaction of [CO(2)] and N on CCER(max) was completely dominated by a general decline of CCER(max) whereas no general decline of the initial slopes occurred in the second period. This response of light response parameters to [CO(2)] and N suggests that, in sugar beet, the decline of CCER in the late season may rely on limiting mechanisms such as photosynthetic acclimation responses to elevated [CO(2)] caused by sink limitations.
Sugars are important signals in the regulation of plant metabolism and development. During stress and in senescing leaves, sugars often accumulate. In addition, both sugar accumulation and stress can induce leaf senescence. Infection by bacterial and fungal pathogens and attack by herbivores and gall-forming insects may influence leaf senescence via modulation of the sugar status, either by directly affecting primary carbon metabolism or by regulating steady state levels of plant hormones. Many types of biotic interactions involve the induction of extracellular invertase as the key enzyme of an apoplasmic phloem unloading pathway, resulting in a source-sink transition and an increased hexose/sucrose ratio. Induction of the levels of the phytohormones ethylene and jasmonate in biotic interactions results in accelerated senescence, whereas an increase in plant- or pathogen-derived cytokinins delays senescence and results in the formation of green islands within senescing leaves. Interactions between sugar and hormone signalling also play a role in response to abiotic stress. For example, interactions between sugar and abscisic acid (ABA) signalling may be responsible for the induction of senescence during drought stress. Cold treatment, on the other hand, can result in delayed senescence, despite sugar and ABA accumulation. Moreover, natural variation can be found in senescence regulation by sugars and in response to stress: in response to drought stress, both drought escape and dehydration avoidance strategies have been described in different Arabidopsis accessions. The regulation of senescence by sugars may be key to these different strategies in response to stress.
Zugl.: Göttingen, Universiẗat, Diss., 2003.
The mechanism of sucrose transport into the vacuole of root parenchyma cells of sugar beet was investigated using discs of intact tissue. Active sucrose uptake was evident only at the tonoplast. Sucrose caused a transient 8.3 millivolts depolarization of the membrane potential, suggesting an ion co-transport mechanism. Sucrose also stimulated net proton efflux. Active (net) uptake of sucrose was strongly affected by factors that influence the alkali cation and proton gradients across biological membranes. Alkali cations (Na(+) and K(+)) at 95 millimolar activity stimulated active uptake of sucrose 2.1- to 4-fold, whereas membrane-permeating anions inhibited active sucrose uptake. The pH optima for uptake was between 6.5 and 7.0, pH values slightly higher than those of the vacuole. The ionophores valinomycin, gramicidin D, and carbonyl cyanide m-chlorophenylhydrazone at 10 micromolar concentrations strongly inhibited active sucrose uptake. These data are consistent with the hypothesis that an alkali cation influx/proton efflux reaction is coupled to the active uptake of sucrose into the vacuole of parenchyma cells in the root sink of sugar beets.
There is evidence suggesting that in plants changes in the photosynthetic source/sink balance are an important factor that regulates leaf photosynthetic rate through affects on the leaf carbohydrate status. However, to resolve the regulatory mechanism of leaf photosynthetic rate associated with photosynthetic source/sink balance, information, particularly on mutual relationships of experimental data that are linked with a variety of photosynthetic source/sink balances, seems to be still limited. Thus, a variety of manipulations altering the plant source/sink ratio were carried out with soybean plants, and the mutual relationships of various characteristics such as leaf photosynthetic rate, carbohydrate content and the source/sink ratio were analyzed in manipulated and non-manipulated control plants. The manipulations were removal of one-half or all pods, removal of one-third or two-third leaves, and shading of one-third or one-half leaves with soybean plants grown for 8 weeks under 10 h light (24 degrees C) and 14 h darkness (17 degrees C). It was shown that there were significant negative correlations between source/sink ratio (dry weight ratio of attached leaves to other all organs) and leaf photosynthetic rate; source/sink ratio and activation ratio (percentage of initial activity to total activity) of Rubisco in leaf extract; leaf carbohydrate (sucrose or starch) content and photosynthetic rate; carbohydrate (sucrose or starch) content and activation ratio of Rubisco; amount of protein-bound ribulose-1,5-bisphosphate (RuBP) in leaf extract and leaf photosynthetic rate; and the amount of protein-bound RuBP and activation ratio of Rubisco. In addition, there were significant positive correlations between source/sink ratio and leaf carbohydrate (sucrose or starch) content; source/sink ratio and the amount of protein-bound RuBP; carbohydrate (sucrose or starch) content and amount of protein-bound RuBP and the activation ratio of Rubisco and leaf photosynthetic rate. The plant water content, leaf chlorophyll and Rubisco contents were not affected significantly by the manipulations. There is a previous report in Arabidopsis thaliana that the amount of protein-bound RuBP in leaf extract correlates negatively with the activation ratio of Rubisco in the leaf extract. Therefore, the results obtained from the manipulation experiments indicate that there is a regulatory mechanism for the leaf photosynthetic rate that correlates negatively with leaf carbohydrate (sucrose and starch) status and positively with the activation state of Rubisco under a variety of photosynthetic source/sink balances.
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