Journal of Agronomy and Crop Science

Published by Wiley
Online ISSN: 1439-037X
Publications
Article
The inter-relationships between fifteen quantitative characters of spring oilseed rape were computed using four “free erucic acid” cultivars viz. Callypso, Semit 2080, Semu DNK 203/84 and Semu 304, grown under two different distances between drill rows (16 and 32 cm) and three population densities (30, 60 and 90 plants/m2). The experiments were carried out in Kiel, West Germany, in 1986 and 1987 seasons. Positive and highly significant values were obtained in the two seasons between seed yield per plant and the characters: dry matter (DM) per plant, per main stem and per branches, number of branches, siliqua per plant or per branches and yield per branches. All the characters that showed strong association with yield/plant behaved in a similar way and similar magnitudes with yield/branches. By contrast, yield/main stem showed different magnitudes in the two years with the previous characters and the association was weak or absent in most cases. Seed index and the quality traits (oil and protein %) did not correlate significantly with the majority of the characters studied. Only the association between DM/main stem and protein content showed highly significant negative values in both seasons. Path coefficient analysis revealed that number of siliqua per plant had the highest direct effect on seed yield/plant in both years. The source character (DM) affected yield/plant indirectly through number of siliqua per plant and the indirect contribution was high m both years.
 
Article
Two field experiments were conducted in 1985 and 1986 on the cotton cultivar, Giza 75 (Gossypiitm barbadense L.) to determine the effect of foliar application of Pix at 0, 10, 20, 40, 60, 80 or 100 ppm on cottonseed yield, seed index, protein and oil contents and fatty acid compositions of cottonseed oil. Pix was sprayed once at 90 days or twice at 90 and 110 days from sowing date. Seed yield/plant or /ha, protein and oil yield/ha, and seed index increased due to the application of Pix compared to the control. The highest response occurred with 40 or 60 ppm Pix and with one application rather than two. The seed protein percentage increased due to Pix application, especially at 10 ppm. A slight increase in seed oil percentage was detected throughout Pix applications. The number of applications had no noticeable effect on seed protein and oil %. Application of Pix caused a general decrease in the saturated fatty acids (myristic, stearic, and palmitic), associated with an increase in the unsaturated fatty acids (oleic and linoleic). These results were confirmed bv the ratio of total unsaturated fatty acids to total saturated (TU/TS). Ten ppm Pix gave the highest TU/TS. Generally, the saturated fatty acids decreased while the unsaturated fatty acids increased with one application rather than two. Palmitic acid was the most abundant saturated fatty acid, whereas linoleic acid was the most abundant unsaturated ones.
 
Leaf area, leaf area ratio (LAR), shoot height and fresh weight of in-vitro rice seedlings cultured under photoautotrophic system with application of exogenous glycinebetaine (Glybet) and choline (Cho) responses to salt stress (342 mm NaCl) for 4 days
Article
Rice reportedly possesses a very low capacity to accumulate glycinebetaine (Glybet), but may be accumulated by the exogenous application of Glybet or Choline (Cho) as an alternative way to improve its salt-tolerant ability. The aim of this research was to determine whether Glybet accumulation could be induced in Thai jasmine rice by the exogenous application of Glybet and Cho, and to determine the effects of Glybet and Cho treatment on various growth parameters of seedlings cultured under salt-stress conditions. Thai jasmine rice seeds were aseptically germinated in vitro on solidified Murashige–Skoog media, supplied with either Glybet or Cho in the culture media for 12 days and then treated with 342 mm NaCl (salt stress) for 4 days. GlyBet content, water relation, photosynthetic capabilities and growth characteristics of salt-stressed seedlings were measured. The addition of Glybet or Cho to plant culture media containing 342 mm NaCl resulted in increased accumulation of Glybet in rice seedlings. Increased Glybet accumulation was strongly associated with a high efficiency of water usage (r = 0.96), which in turn correlated with increased maximum quantum yield of PSII (Fv/Fm) (r = 0.86). Moreover, the pigment concentrations of seedlings cultured under salt stress were maintained by a function of Glybet, led to high efficiency of photochemical and non-photochemical quenching of PSII as well as to exhibit on net photosynthetic rate. Thus, our results suggest that the addition of either Glybet or Cho to the plant growth media can improve growth performance under salt stress conditions by increasing the salt tolerance of Thai jasmine rice. The exogenous application of Glybet and/or Cho to culture media may be an effective method of improving resistance to salt stress via the promotion of Glybet accumulation with in rice seedlings.
 
Article
Leaf extracts and mulch from 14 MPTs were used to study their effects on germination, initial growth and nodulation of cowpea. Aqueous leaf extracts of , , and full concentrations were added to cowpea seeds placed in Petri dishes. In the pot experiment, cowpea was planted in plastic pots filled with 1200 g of soil, and mulch was either surface-applied or incorporated into the substrate at rates equivalent to 5, 10 and 20 tons · ha−1. Leaf extracts from Gliricidia sepium, Senna siamea, Milletia thoningii, Grewia pubescens and Tetrapleura tetraptera reduced cowpea germination significantly at concentrations above 25 % of the full concentration 7 days of incubation. Root length was also strongly reduced by extracts from Gmelina arborea, Senna siamea, Alchornea coordifolia, and Tetrapleura tetraptera. These inhibiting effects were also observed in the pots. Mulch incorporation significantly reduced growth and nodulation of cowpea in the pots. These reductions were more pronounced with the incorporation of mulch from fast decomposing trees such as Leucaena leococephala, Gliricidia sepium and Grewia pubescens. Although Leucaena leucocephala and Gliricidia sepium released much nitrogen, they strongly reduced cowpea growth when incorporated. This may suggest that other reasons than N immobilization caused growth reduction when the plant residues were applied to cowpea.
 
Article
The effect of the application of abscisic acid (ABA, 10−4 mol 1−1), benzyl adenine (BA, 10−6 mol - 1−1), N6-m-hydroxybenzyl-adenosine (HBA, 10−6 mol - 1−1) and combinations of these cytokinins with ABA on the transport of 14C-sucrose into the developing kernels of winter wheat, their number and mass, was studied. Growth substances were applied in the period 10 to 5 days before anthesis and their effects were examined 4 and 18 days after anthesis on ears that were detached 10 days before anthesis and then cultivated on a complete nutrient solution. The stimulating effect of HBA on the transport of 14C-sucrose, number of kernels and their mass was higher than that of BA. ABA partly decreased the stimulating effect of cytokinins and reduced up to several days after anthesis the transport of 14C-sucrose to the developing kernels, their number and mass. The results revealed that a higher level of cytokinins in the period before anthesis could effectively interact with the inhibiting effect of ABA in that period and influence the accumulation of assimilates in the kernels.
 
Article
Seedlings of a maize hybrid sensitive to chilling initially grew in the growth chamber of the phytotron at 20/ 17°C (day/night) and after the formation of the fourth leaf, the soil temperature was lowered to 5°C. Under such growth conditions the dynamics of dry weight change, gas exchange and the distribution of 14C-assimilates in seedlings were examined. The low soil temperature inhibited daily growth of dry weight of whole seedlings more than their photosynthesis. Simultaneously, it was also responsible for a greater increase in dissimilative losses. During 37 hours (day-night-day), following exposure to 14CO2, dissimilation in seedlings in cool soil (5°C) and in non-chilling conditions amounted to 35.1 % and 23.4 % of assimilated 14C (AC), respectively. At lower soil temperature relatively high dissimilative losses were observed on the first day after exposure (23.5 %), lower at night (9.9 %) and the lowest on the following day - merely 1.7 % AC. Higher losses of 14C under chilling conditions occurring on the first day were a result of limited photosynthetic refixation of 14CO2 At night, however, they were associated with a prolonged period of intensive translocation of assimilates to the stem. It was assumed that an excessive accumulation of assimilates in leaf blades might be an additional factor responsible for increased dissimilative losses at low temperature during the first twenty-four hours. In the third period of measurements, as a result of a limited transport of 14C, dissimilative losses were lower than in previous ones and were not dependent upon soil temperature.
 
Article
The transport and distribution of 14C-sucrose and 14C-BA were studied in internode segments with ear of two winter wheat cultivars with a different mass of kernels in the period prior to anthesis. Both labelled substances were transported intensively into all the developing parts of the car, namely the rachis became the main site of 14C-BA accumulation. While the difference in the transport of l4C-sucrose among the cultivars was not unambiguous, a more intensive transport of 14C-BA was observed in the cultivar with a simultaneously higher mass of 1000 kernels. The higher level of zeatin and zeatin riboside in kernels detected in this cultivar suggested that in the period before anthesis it could accumulate (due to intensive transport, probably from the roots) an important part of cytokinins, available for the early stages of kernel development.
 
Article
The role of leaves, stem and reproductive parts in 14CO2 fixation and subsequent photosynthate translocation was studied in Indian mustard (Brassica juncea L.) at three growth stages. The data indicated that leaves, stem and pods are important sources of photosynthates for seed filling. At bud emergence stage leaves are the principle site of 14CO2, fixation. The contribution of leaves declines at subsequent stages, where as the contribution of pod walls increased from bud emergence stage to ripening stage. The contribution of the stem remains more or less constant at all three growth stages studied. Although stem can fix 14CO2, at bud emergence and flowering stages it imported 14C-photosynthates from leaves. However, stem exported photosynthates during subsequent growth stages.
 
Article
Excised ears of Triticum durum (HD 4502 and B 449) and T. aestivum (Kalyansona and Kundan) varieties were cultured in 14C-sucrose, and the uptake and distribution of 14C within the ear was examined. Species-level differences in the distribution of 14C to spikelets at basal, middle and apical positions in the wheat ear (vertical distribution) were observed. T. aestivum var. Kalyansona and Kundan showed no limitation in vertical translocation of 14C-sucrose, whereas in T. durum there was a decrease in the distribution of 14C to apical spikelets. Within a spikelet, the distribution of 14C-sucrose to distal grains was significantly less than that to proximal grains in all the genotypes. Translokation von 14C-Sukrose innerhalb der Ähre von Durum-und Aestivumweizen-varietäten Abgetrennte Ähren von T. durum (HD 4502 und B 449) und T. aestivum (Sorten: Kalyansona und Kundan) wurden in14C-Sukrose kultiviert und Aufnahme und Verteilung von14C innerhalb der Ähren untersucht. Die artspezifischen Differenzen in der Verteilung von14C im Hinblick auf die Ährchen im basalen, mittleren und apikalen Teil der Weizenähre (vertikale Verteilung) wurden beobachtet. Triticum aestivum var. Kalyansona und Kundan zeigten keine Limitierung in der vertikalen Translokation von14C-Sukrose, während bei Triticum durum eine Abnahme in der Verteilung von14C zum apikalen Ährchen vorlag. Innerhalb der Ährchen war die Verteilung von14C-Sukrose zu den distalen Körnern bei allen Genotypen signifikant geringer als zu den proximalen Körnern.
 
Article
The transport and distribution of 14C-sucrose and 14C-BA were studied in internode segments with ear of two winter wheat cultivars with a different mass of kernels in the period of kernel formation. While MC-sucrose was transported and accumulated intensively in the developing ear, 14C-BA was transported much less and only a small part of it was found in the ear. With the ear development the accumulation of both 14C-sucrose and 14C-BA in the ear increased but the 14C-BA distribution pattern (ratio of the internode/kernel and the rest of the ear) did not change significantly. In the period of one to two weeks after anthesis the accumulation of 14C-sucrose and 14C-BA was higher in the kernels of the Slavia cv., i.e. in the cultivar with a higher mass of kernels.
 
Article
Maize (Zea mays L.) plants were grown in the field and labelled with 14CO2 at four leaf positions from silking up to maturity. The ear leaf was the most important source of labelled photosynthates to the ear, followed by the first leaf blade above and below the ear. The movement of labelled assimilates from the second leaf blade below the ear was predominantly downwards. The ear became an important sink soon after silking and continued in importance till harvest. Initially assimilates were partitioned within the ear as husk < cob < grains but at harvest as grains < cob < husk. There was considerable remobilization of assimilates from the husk and stem. Removal of leaves drastically altered the pattern of distribution of labelled photosynthates and the direction of movement was determined by the position of the source leaf blade and the defoliation treatment. Darkening the leaf blades did not much alter the translocation of the labelled photosynthate and increased slightly its proportion to the grains. The removal of the ear severely altered the pattern of distribution of 14C, which was mostly deposited in the stem.
 
Article
In a pot experiment under controlled condition, Leymus chinensis was grown at five soil water contents and two diurnal temperature variation levels. The leaf relative water content of L. chinensis decreased under soil drought conditions, and increased at high diurnal temperature variation (30/20 °C). Severe and very severe soil drought remarkably reduced photosynthetic rate, stomatal conductance, transpiration rate and water use efficiency (WUE), especially at the low temperature variation. Severe drought mainly increased the specific radioactivity of 14C of sheaths, roots and rhizomes, but significantly decreased that of fed leaves and the not fully expanded leaves. Root percentage of total radioactivity remaining in the whole plant increased from 15 % at 30/25 °C to 28 % at 30/20 °C. Leaf carbon stable isotope composition (δ13C) increased with soil drought, ranged from −26 ‰ of the well-watered to −24 ‰ of severe drought treatments. High diurnal temperature variation improved leaf water status, and increased partitioning of carbon to root and δ13C values, especially under severe soil drought conditions. In conclusion, higher diurnal temperature variation enhanced the resistance of the plant to drought.
 
Article
The effects of drought on growth, pigments and 14CO2 assimilation were studied in three sorghum cultivars. Water stress applied either at the vegetative or at the reproductive stage was found to reduce relative growth and net assimilation rates. Root growth was less affected by water stress and in certain cases it was increased; consequently, the root/shoot ratio was improved. The sensitivity to drought stress was greater at the reproductive than at the vegetative stage. Dorado was the most drought-tolerant and Giza 15 the least drought-tolerant cultivar, as determined by calculation of the drought susceptibility index for total green leaf area and shoot dry weight. Short-term water stress in the vegetative phase (7 days) improved the chlorophyll content in leaves, and long-term stress in the vegetative and reproductive phases reduced chlorophyll content. Carotenoid content, in general, was not changed by drought stress. 14CO2 photoassimilation indicated that soluble, insoluble and consequently total photosynthates were reduced at the end of the stress period at both stages. Drought plus defoliation appeared to increase both chlorophyll content and 14CO2 photoassimilation, to a certain extent, as compared with drought alone.
 
Article
Effect of plant growth regulators Naphthalene acetic acid (NAA), Gibberellic acid (GA3) and Kinetin on 14CO2 assimilation, partitioning of 14C into major biochemical fractions and translocation of assimilates was studied in different parts of Indian Mustard (Brassica juncea) at late ripening stage. Leaves, stem and pod walls are photosynthetically active and are important sources for seed filling. NAA and kinetin increased the 14CO2 assimilation rate in all the three photosynthetically active parts. All the three growth regulators increased the export of 14assimilates out of source organs and increased the movement of assimilates into the reproductive parts (pods). The increased movement of photoassimilates into the developing pods may be due to the stimulation of sink activity by the growth regulators which resulted in the higher demand for photoassimilates. It was suggested that growth regulators may increase yield by altering distribution of assimilates in the mustard plants.
 
Article
Effect of heat stress on 14CO2 assimilation and translocation by different parts was investigated in Indian mustard (Brassica juncea (L.) Czern.]. Heat stress reduced 14CO2 assimilation by leaves, stem and pods. Export of radioactive carbon from upper and lower leaves, upper and lower stem and stem of terminal raceme was inhibited in response to heat stress. Import of 14C-photosynthates into pods was also inhibited by heat stress indicating reduction in sink strength of the developing pods.
 
Article
The modulation, nitrogen fixation and nitrogen uptake of four pigeonpea genotypes belonging to extra short duration, short duration and long duration maturity groups grown on an Inceptisol were studied to examine why, despite the poor nodulation of pigeonpea in this soil, it still produces greater yields, than in Alfisols and Vertisols. The percentage nitrogen derived from the atmosphere (%Ndfa) was estimated by 15N natural abundance and N-difference methods using a long duration sorghum as the non-fixing reference crop. In general, nodulation of pigeonpea in the Inceptisol was much lower than that reported in Alfisols and Vertisols. The above-ground dry matter ringed from 3.1 to 17.1 t ha−1 while the N uptake ranged from 62.3 to 215 kg ha−1 The fallen plant parrs of pigeonpea genotypes ranged from 1.4 to 4.9 t ha−1 and their N contents ranged from 25 to 84 kg ha−1. The estimates of percentage Ndfa obtained by the two methods were different. Those obtained by the 15N natural abundance appeared more appropriate as the δ15N of sorghum harvested along with short duration pigeonpea and later when it was mature did not change significantly. The extra short duration pigeonpea genotype ICPL 84023 contained very little N from atmospheric N2, while the short duration pigeonpea cv. ICPL 151 had 17% Ndfa and the long duration genotypes. ICPL 366 and T7 had up to 36 % Ndfa. It can be concluded that one of the causes of high yields of pigeonpea on Inceptisols compared to Alfisols and Vertisols despite poor nodulation could be the high N supplying capacity of these Inceptisols. Strategies have been suggested as to how pigeonpea genotypes grown in Inceptisols could improve their nodulation and nitrogen fixation and thus better contribute to a sustainable agriculture.
 
Article
Two lentil cultivars, UJ1 and ILL, have been introduced into the farming system of the Middle East. The influence of P on their potential to fix N2 under drought conditions is lacking. A factorial field experiment was carried out at Taibeh (500 mm yr−1) and Muru (300 mm yr−1), where three rates of P, two lentil cultivars and barley were included. Phosphorus was the main plot, while lentil and barley were grown randomly in the subplots. A typical experiment treated with unlabeled 100 kg N ha−1 with similar P rates was conducted at the Taibeh site. Both cultivars on each site did not differ significantly at different levels of P regarding the biological yield. At each P level, both cultivars derived similar nitrogen percentages from atmosphere (per cent Ndfa), except at Taibeh with the intermediate rate of P, where ILL derived (66.1 %) compared to UJ1 (40.3 %). At Taibeh, the average percentages of N in the grain and straw were 4.17 % and 1.14%, respectively, and were significantly higher than at the Muru site (3.38 %, 1.29 %). The relatively drought-like conditions at Muru reduced percentage Ndfa to ∼28 but this was increased by P addition. Nitrogen addition reduced partitioning of N (N index) from ∼0.70 % to ∼0.55 % and decreased P percentage in the grain from ∼0.40 % to ∼0.31 % and in straw from 0.11% to 0.07 % due to early maturation. In spite of the indigenous Rhizobium efficiency to fix N2, only 52.0 % and 42.3 % of the plant N was derived from the atmosphere at Taibeh and Muru, respectively, causing depletion of soil N reservoir.
 
Article
Soil degradation and depletion of soil nutrients are among the major factors threatening sustainable cereal production in the Ethiopian highlands. Fertilizer use as a means of mitigating nutrient depletion has become widely accepted. The fate of fertilizer nitrogen (N) applied to a semidwarf bread wheat system was determined in microplots receiving 41 kg N ha−1 in the form of urea labelled with 5.617 % atom excess 15N, without and with the application of phosphorus (P) at 20 kg P ha−1. The study was conducted in three different agro-ecological zones at 2200, 2400 and 2800 m above sea level (masl) (Kulumsa, Asasa and Bekoji, respectively) in the south-eastern Ethiopian highlands. Yield and yield response to N diminished with elevation, while the response to P increased with elevation, with a significant increase in wheat grain yield observed at Bekoji (2800 masl). N harvest index and N use efficiency improved in response to P application at Asasa (2400 masl). Crop removal accounted for 25–64 and 36–64 % of the applied N without and with P, respectively. The corresponding fractions of 15N recovered in the soil ranged from 2.9 to 3.5 % and from 3.2 to 3.7 %, respectively. Recoveries of applied 15N were 67 and 52 % at Kulumsa and Asasa, but only 25 % at the highest elevation site, Bekoji. Fertilizer P significantly enhanced N recovery at Asasa (60 %) and Bekoji (36 %), but not at Kulumsa, where the soil had a high level of residual P from previous applications. The fraction of 15N recovered in the soil–plant system was rather low at Bekoji. However, the rate of 15N recovery was significantly improved (by 37 %) when fertilizer P was added to the soil. Across all locations, the unaccounted 15N may have been lost primarily through denitrification and volatilization.
 
Article
A lysimeter trial is described in which the fate of 15N was monitored in a sand, loam and clay soil by using it over a period of 6 years. The following results were obtained. 1. The uptake of fertilizer nitrogen by plants, determined by using 15N, is lower than by using the conventional method (“difference method”). Nitrate 15N is better utilized by the plants than is ammonium 15N. The total nitrogen uptake only gives hints of these differences. 2. The extent to which plants utilize fertilizer 15N is between 38 and 58%; in the case of the method of differences this figure is between 48 and 68%. 3. Plants remove more nitrogen from the soil when fertilizer N is applied than when without fertilization. The influence of these two nutrient forms is of subordinate significance. 4. After a trial period of six years between 26 and 54 % of the fertilizer 15N remains in the soil. The resulting sequences are clay > loam > sand > and ammonium > nitrate. 5. The immobilization of the fertilizer 15N is most pronounced in the first four years but then decreased considerably; in the case of the sandy soil it is then even slightly regressive. 6. The biggest part of the 15N is deposited in the uppermost layer of the soil. The amount of 15N in the deeper layers is diminished appreciably. The type of soil has a greater influence than the form of nitrogen. 7. If the amount of fertilizer N left in the soil is compared with the N losses from the soil's reservoir (plants' uptake, leaching) there is a negative balance for the soil nitrogen which mainly is determined by the type of soil.
 
Article
In intensive farming systems, farmers split up and apply the N fertilization to winter cereals and oilseed rape (OSR) at several dates to meet the need of the crop more precisely. Our objective was to determine how prior fertilizer N application as slurry and/or mineral N affects contributions of fertilizer- and soil-derived N to N uptake of barley (1997), oilseed rape (OSR; 1998) and wheat (1999). In addition, residual fertilizer N effects were observed in the subsequent crop. Since autumn 1991, slurry (none, slurry in autumn, in spring, in autumn plus in spring) and mineral N fertilizer (0, 12 and 24 g N m−2) were applied annually. Each year, the treatments were located on the same plots. In 1997–1999, the splitting rates of the mineral N fertilization were labelled with 15N. Non-fertilizer N uptake was estimated from the total N uptake and the fertilizer 15N uptake. All three crops utilized the splitting rates differently depending on the time of application. Uptake of N derived from the first N rate applied at the beginning of spring growth was poorer than that from the second splitting rate applied at stem elongation (cereals) or third splitting rate applied at ear emergence or bud formation (all three crops). In contrast, N applied later in the growing season was taken up more quickly, resulting in higher fertilizer N-use efficiency. Mineral N fertilization of 24 g N m−2 increased significantly non-fertilizer N uptake of barley and OSR at most of the sampling dates during the growing season. In cereals, slurry changed the contribution of non-fertilizer N to the grain N content only if applied in spring, while OSR utilized more autumn slurry N. In OSR and wheat, only small residual effects occurred. The results indicate that 7 years of varying N fertilization did not change the contribution of soil N to crop N uptake.
 
Article
A pot experiment was carried out in a climatic chamber to study 15N-uptake, translocation and recovery in soybeans [Glycine max (L.) Merr.] as affected by a 13 day interval of water deficits (wd) starting at flowering. Ten or 40 mg 15N (500 or 2000 p.p.m. 15N) was injected at 0.4 m depth into the soil 3 days after flowering (3 DAF). A dose of 10 mg 15N, resulted in a translocation of 50 and 80 % to the shoot at 7 and 13 DAF, respectively; thus the uptake of 15N into the plant organs was limited by the low remaining 15N in the soil after 7 DAF. Therefore, only results referring to the 40 mg 15N application are presented here. The daily 15N-uptake of well-water (ww) plants during the 10 days of investigations was about c. 2.5 mg 15N, it was significantly higher than under wd at 7 DAF and tended to be higher at 13 DAF. The reduction by wd was also evident by a lower recovery of 15N (55 % instead of 75 %) at 13 DAF. In almost all leaves and pods there was a trend to a lowered translocation (mg 15N per organ) under wd when compared with the ww plants at 7 and 13 DAF; lowering due to wd was strongest and significant in upper leaves and pods at 13 DAF, whereas translocation to stems was even slightly increased. Relative accumulation of 15N (mg g−1 dry matter) in leaves, stems and pods increased from the bottom to the top indicating an higher sink activity of younger organs. Water deficits tended to lower this relative 15N-accumulation in all leaves and pods at 7 and 13 DAF, and caused a significant reduction in upper leaves and pods at 7 DAF. Absolute and relative 15N-accumulation in stems tended to be affected differently by wd, being unaffected or slightly decreased at 7 DAF, but increased at 13 DAF. These differential effects of wd are discussed.
 
Article
N-uptake and N utilization of different fertilizer types by winter wheat – pot experiments with 15N The efficiency of top dressing urea, ammonium nitrate and ammonium sulphate fertilizers on winter wheat grown on loamy sand and loessial black soil was studied. At a rate of 0.5 g N per pot on the loamy sand 20 % volatilization losses of NH3 occurred with urea and 10 % on the loessial black soil with urea resp. ammonium sulphate. The grain yields an N removal correspond to these results. At an amount of 1.6 g N per pot the N-uptake of 15N ranged from 0.589 g (urea) on sandy soils to 1.279 g (ammonium nitrate) which agrees with 76 % an 91 % of the total N uptake. On black soil 0.675 g (urea) and 1.038 g (ammonium nitrate) or 44 % and 51 % of the total uptake are found.
 
Article
An archaeological find of oil-seed rape from the 16th century discovered in Heide in Holstein, Northern Germany During archaeological excavations in the cellar of a 16th-century house in Heide, Northern Germany, four stocks of crops were found. Two of them consisted of barley, one of rye and the last one of Brassica seeds. The circumstances of the finds, as well as the morphological criteria of the Brassica seeds, which also occur as a weed in the barley stocks, make it virtually certain that the Brassica seeds are oil-seed rape Brassica napus.
 
Article
This investigation tested the influence of thermal treatment of seeds at various stages of imbibition on the germination percentage, speed and growth response of seeds and seedlings. Seeds of sorghum (Sorghum bicolor L Moench) were treated in 2, 4 or 6 g NaCl l−1 solutions and exposed for 2 h to 45 °C during the first, second or third days of imbibition. Thereafter, the seeds were dried and germinated at 42/19 °C (day/night temperature). Salt treatments did not improve the final germination percentage but increased germination speed over untreated seeds. The higher the salt concentration used, the greater the dry weights of plumules and radicles. Thermal treatment on the third day of imbibition yielded higher germination percentages than untreated seeds, while thermal treatment on the second day gave faster germination. Both the second and third day thermal treatments gave superior germination indices and higher plumule-to-radicle ratios. It is concluded that thermal treatment may assist in acclimating seeds to heat stress.
 
Article
This study was conducted to evaluate the application of carbon isotope discrimination (CID) as a selection criterion for improving water use efficiency (WUE) and productivity of barley (Hordeum vulgare L.) under field and drought-stress conditions in a greenhouse. A total of 54 genotypes were screened for variability in CID under field conditions, while 23 genotypes were evaluated under water-deficit conditions in the greenhouse. A survey of leaf CID of 54 genotypes at two field locations showed more than 2.14‰ difference between extreme genotypes. Significant (P ≤ 0.05) genotypic variation was found in WUE and CID that had a negative strong correlation. There was a negative correlation between leaf CID and aerial biomass in the greenhouse and among six-row genotypes in the field. Correlations between leaf CID across field locations and across irrigation regimes in the greenhouse were significant (experiment 1, r = 0.79 and 0.94 for six- and two-row genotypes), suggesting stability of the CID trait across different environments. Overall, these results indicate the potential of leaf CID as a reliable method for selecting for high WUE and productivity in barley breeding programmes in the Canadian prairies. Further work is currently underway to determine heritability/genetics of leaf CID and application of molecular marker-assisted selection for the traits in barley breeding programmes.
 
Article
Grain protein content is one of the most important attributes in bread making quality. Several studies have reported that the type of, and the balances between, storage protein (i.e. gliadins and glutenins) are also relevant. Generally, the modern cultivars present less grain protein content than their predecessors, suggesting that breeding may have reduced baking quality while improving yield. Furthermore, there is little information on whether, and eventually how, breeding influences the types of protein synthesized in the grains, and the sensitivity of the type of protein and baking quality to changes in the environment. This study aimed to determine the stability in baking quality in wheat cultivars released at different eras to variation in the duration of the pre-anthesis period without changes in the sowing date. The experiment studied the combination of three cultivars released in 1940, 1964 and 1994 at two different durations from sowing to anthesis (because of exposure to different photoperiods during stem elongation in the field). Modern cultivars showed lower grain protein content than the oldest ones (11 vs. 14 %). There were no correlation between grain protein content and baking quality (assessed by Zeleny test), indicating that protein type is more important than grain protein content. Gliadins were more variable than glutenins because of differences between cultivars and flowering dates. Wheat breeding also seemed to have improved the stability of quality variables in response to environmental variation during the pre-anthesis period (when yield potential is being determined).
 
Article
Sorghum hybrid CSH-6 was grown in fields in Delhi, India between July–November 1986 in order to study the effect of nitrogen nutrition and irrigation on dry matter accumulation, grain yield and water use. The treatments included 40 Kg Nha−1 combined with two irrigations (30 DAS, 60 DAS), one irrigation (60 DAS) and no irrigation respectively. Rainfall during the crop season was only 17 cm. The unirrigated plants were considerably water stressed and exhibited very low leaf water potential, less leaf area, delayed anthesis, longer crop duration but shorter grain filling duration. The ears showed sterility and yield was only 0.41 t ha−1 without nitrogen fertilization. Addition of nitrogen fertilizer had no significant effect on yield in unirrigated plants. A single irrigation 60 DAS increased yield due to increase in both grain number and grain weight per ear in fertilized and unfertilized crop respectively. Two irrigations in the unfertilized crop increased the yield to 2.2 t ha−1 while similar treatment in the fertilized crop did not increase the yield significantly. Irrigation increased the WUE for grain yield. The results indicate that nitrogen stress and water stress reduced grain yield primarily through grain number rather than grain weight. Irrigation relieved both water stress and nutrient stress. Nitrogen nutrition was not beneficial under severe water stress conditions but was considerably helpful under mild stress. Biomass, grain yield and harvest index show significant correlation with preanthesis water use.
 
Article
In sweet potato tuber, which is a tropical plant, long-term storage leads to loss of water and carbohydrate, thus water mobility was investigated using 1H-NMR spectroscopy. Electrolyte leakage indicated that tubers stored at 15 °C for 1 year were partly injured and that frozen-thawed tissues were dead. Nuclear magnetic resonance (NMR) spin–lattice relaxation time (T1) and spin–spin relaxation time (T2) clearly increased with the duration of storage, whereas these values decreased in the dead tissues. Furthermore, Arrhenius plots for T1 and T2 were determined at temperatures ranging from 20 to 0 °C in 2.5 °C steps. In the fresh tubers, a strong converse temperature dependency was shown in the T2 measurement. On the contrary, there was no temperature dependency in the T2 of the dead tissues. Thus, the existence of inverse temperature dependency reflected tissue viability. Additionally, any change in the T2 of the fresh tubers occurred at about 14 °C, which virtually coincided with the storage temperature of 15 °C. The slope change in T2 might have responded to a physiological change as a primary event. In conclusion, monitoring water status by NMR could provide early identification of changes in the quality of post-harvest crops; this method shows great promise for use in environmental-stressed crop yield research.
 
Article
The effects of 2,4-D with or without Azospirillum hra-iiknse (Sp7) on nodulation of wheat (cv HD2428) have been investigated under hydropooical conditions. In the nutrient medium, varying concentrations of N and 2,4-D were used for growing wheat seedlings, N free Hoaglatid solution along with 2,4-D (0.5 ppm) was found to be the best concentration for noduiation and growth of the seedings, The nilrogenase activity (acetylene reduction y was relatively higher in plants treated with 2,4-D artd Azospirillum ihan with Azospirillum alone. This seemed to be due to the formation of nodule like stiucture serving as mche for azospirilla to protect it from oxygen. These results confirmed tlie nitrogenase activity of Azospirillun brasiknse in association with the 2,4-D induced nodules of wheat. Plants inoculated with Azospirillum either alone or with 2,4-D were transplanted info pols. The photosynthctic rate, chlorophyll content. NRA, grain yield and N content were found to be higher in inoculated plants. The translocation of current photo-synthates (14C sucrose studies) towards roots was higher in these treatments. Thtss the growth of Azospirilfum and nodule formatioo depend on availability of current photosynthatcs of hosl plants.
 
Article
The purpose of this study was to assess improvements in performance of maize hybrids during a 20-year period. Data on FAO 100 and 200 hybrids, released by the former Yugoslav Committee for Releasing Varieties, were utilized. For FAO 100 hybrids group, yield increased 0.0015 Mg ha-1 year-1 but was not significant. Breeding resulted in a significant decrease in days to silking. In the FAO 200 group, yield increased on the average 0.046 Mg ha˜ year-. The genetic gain was not significant. A performance index, based on yield and several other traits, increased significantly during the period for both groups of hybrids, but the increase due to breeding was significant for the FAO 200 hybrids only.
 
Article
The objective of the study was to test the feasibility of coexistence between genetically modified (GM) and non-GM maize under real-life agronomical conditions. GM hybrid maize with the event MON810 (Bt maize) was drilled at 30 sites in fields surrounded by near isogenic conventional maize, although only 27 sites could be finally evaluated. Field sizes of Bt maize varied between 0.3 and 23 ha, and the flowering period of the Bt and conventional maize was synchronous. At some sites, different planting dates of GM and non-GM maize or an earlier ripening conventional maize were tested in additional strips to obtain altered flowering and thereby reduce cross-pollination. The overlapping of flowering periods was successfully avoided only at two sites where non-GM maize was planted 25 or 28 days later. During harvest, samples were taken from the conventional maize in strips at distances of 0–10, 20–30, and 50–60 m to the Bt maize fields to assess the GM DNA content as a function of distance. Sampled materials included chaffed plant material intended for silage (18 sites), grains (eight sites), or crushed husks and cobs (one site). Wind effects were taken into account by sampling in all four compass directions. Quantitative PCR was used to detect the event specific MON810 DNA sequence in sampled materials. The analysis was conducted by two certified independent diagnostic testing companies selected in a pre-test. Taking averages over all compass directions and the two laboratories no samples collected beyond 10 m had levels of GM above the threshold of 0.9 %. In conclusion, the data indicate that coexistence of GM and conventional maize is possible under real-life large-scale agronomical conditions. Levels of GM DNA in harvested grain resulting from outcrossing can be managed to levels below 0.9 % by simply planting 20 m of conventional maize as a pollen barrier between adjacent fields.
 
Article
A field experiment was conducted during khariff 1984 in sandy clay loam soil under irrigated condition at the Tamil Nadu Agricultural University, Coimbatore, with a view (i) to find out the possibility of introducing short duration dwarf variety of sorghum CO 22 as an intercrop with pigeonpea genotypes, (ii) to study the effect of different plant population levels and intercropping of sorghum CO 22 on pigeonpea genotypes, and (iii) to find out compatible pigeonpea genotypes and plant population level for pigeonpea based intercropping system with sorghum CO 22. It was observed that increased plant density significantly increased the dry matter production, leaf area index (LAI) and crop growth rate (CGR) during early stages and reduced the net assimilation rate (NAR), relative growth rate (RGR) and CCR during later part of the growth. Intercropping of sorghum CO 22 significantly reduced the dry matter production LAI, CGR, NAR and RGR. Plants in the intercropped stands recorded higher CGR, NAR and RGR during later part of the growth. Among pigeonpea genotypes CO 5 was much affected due to intercropping with sorghum CO 22.
 
Article
Brassinosteroids are plant steroid hormones important for plant growth and development. They include more then 70 compounds. Their physiological effect and possibilities of practical use are still being investigated. In this study, we evaluated the effects of exogenously applied 24-epibrassinolide, one of the brassinosteroids, on the grain yield and grain chemical composition (carbohydrates, proteins, fats and minerals) of wheat. Moreover, we analysed the presence of brassinosteroids in newly formed wheat grains after exogenous plant treatment with 24-epibrassinolide. Experiments were performed in a vegetation hall (plants cultivated in pots) and in the field. The tested regulator was applied via 48 h seed soaking (1 mg·dm−3) or spraying plants at the heading stage (0.25 mg·dm−3). 24-epibrassinolide increased grain yield in plants growing in the field (by about 20 %), but not in plants cultivated in vegetation hall. Grain chemical composition was altered by 24-epibrassinolide in wheat growing in the vegetation hall; the content of soluble sugars was higher while that of total fats and calcium was lowered, whereas the starch and soluble protein content was not affected. The effect of the hormone was in these cases dependent on the method of its application. As for plants cultivated in the field, the hormone impact on the amount of carbohydrates, proteins, fats and minerals contained in the grains was rather negligible. In wheat grains, the presence of brassinolide, castasterone and 24-epicastasterone was found. 24-Epibrassinolide applied exogenously to plants was not accumulated in newly formed grains. Additionally, significance of ethanol as a hormone solvent is discussed.
 
Article
A field experiment was conducted during kharif, 1985 and summer, 1986 in sandy clay loam soil under irrigated condition at Tamil Nadu Agricultural University, Coimbature, with a view (i) to assess the suitable method of planting of sorghum CO 24 when intercropped with soybean, (ii) to evaluate the suitable planting ratio of sorghum - soybean intercropping system, (iii) to find out the compatible population level of soybean when intercropped with sorghum CO 24. Direct sown sorghum at 4: 2 and 2: 2 recorded grater leaf area (LA) compared to transplanted sorghum in both kharif and summer. Sorghum transplanted with 14 days old seedlings recorded higher Crop Growth Rate (CGR) compared to 21 days old seedlings. Increased Net Assimilation Rate (NAR) were recorded in sorghum transplanted with 14 days old seedlings as compared to direct sown and 21 days old transplanted crop. Transplanted sorghum recorded higher Relative Growth Rate (RGR) as compared to direct sown sorghum. Summer sorghum recorded higher Relative Growth Rate (RGR) as compared to kharif season.
 
Article
The paper presents estimates of the relative efficiency (RE) of the 35-1 (V) and 35-2 (III) fractional factorial designs. Three variants of each fractional design were generated from a one-replicated 35 full factorial design applied in field experiments with pea (Pisum sativum L.). Plant height and seed yield were determined in the study. Additional measurements of soil properties (pH, P, K, Mg) and plant traits determined on the alleys between experimental strips, sown with a single cultivar, were performed in regular nets of sampling points. Geostatistical methods were used to estimate the spatial variation of the experimental field. Information on spatial variation was included in the statistical analysis. It was found that in the 35-1 (V) fractional designs most of the significant effects were the same as in the 35 full factorial design. Information from these two types of design was similar, although there was a distinct tendency to higher values of the coefficient of determination R2 for linear models of the 35-1(V) designs. The 35-2 (III) fractional designs were more variable in detecting significant effects. Generally, mean RE was higher in the 35-2 (III) design than in the 35-1 (V) design, but at the same time the standard error of the latter one was distinctly lower. It was also demonstrated that in agricultural field experiments factorial fractional designs are a very good alternative to full factorial designs as concerns the estimation of main and two-factor interaction effects in the case of the 35-1 (V) designs and main effects in that of the 35-2 (III) designs. Even if the designs have a highly reduced number of treatments to be tested they are equally or more effective than the original 35 design from which they were generated, provided that the generator is chosen very carefully and the spatial variation of the experimental field is considered in statistical analysis of the experimental data.
 
Article
Laboratory experiments were conducted to study the effects of light, different growth media, temperature, and salt concentrations on the germination ratio, mean germination period, and the beginning of germination of cotton seeds, Gossypium hirsutum L., cv. Nazilli 87. All factors considerably affected the germination rate of cotton seeds, ranging from 47% at darkness to 96% at 16 h of artificial light. The mean germination period varied from 5.6 days at 15°C and 1.3 days at 30°C under illumination and lasted longer at dark. The germination ratio was 94 % without additional salt and decreased from 63 % at salt concentration of 175 mM NaCl 1−1 to only 8.7 % at 300 mM 1−1. The mean germination period ranged from 5.28 days to 13.50 days at salt concentrations of 0–300 mM NaCl l−1, respectively.
 
Article
Salt (NaCl)-induced regulation of some key physio-biochemical characteristics in two okra (Abelmoschus esculentus L.) cultivars (Nirali and Posa Sawni) was examined under greenhouse conditions. Plants of both cultivars were subjected for 30 days to sand culture salinized with four salt levels [0 (control), 50, 100 and 150 mm NaCl] in Hoagland’s nutrient solution. Salt stress significantly reduced the shoot and root fresh weights, transpiration rate, chlorophyll b content, net CO2 assimilation (A), transpiration rate (E), while enhanced leaf and root Na+ and Cl– concentrations in both cultivars. In contrast, chlorophyll a content, stomatal conductance (gs), leaf internal CO2 (Ci), Ci/Ca ratio, water-use efficiency (A/E) and fluorescence characteristics such as photochemical quenching (qP), non-photochemical quenching (NPQ), efficiency of PS-II (Fv/Fm), proline contents, and leaf and root K+, Ca2 + and N contents remained almost unaffected in both lines due to salt stress. The efficiency of PSII (Fv/Fm), A, chlorophyll b, root fresh weight and root N were higher in relatively salt tolerant cv. Nirali, whereas leaf Na+ and root Cl– were higher in cv. Posa Sawni. The relatively more reduction in growth in the cv. Posa Sawni was found to be associated with higher accumulation of Na+ in its leaves and Cl– in roots.
 
Article
Plant growth regulator effects on the wheat ear in relation to the conditions during grain filling period Chlorflurenolmethylester (CFM) for inhibition of indole-3yl acetic acid (IAA) translocation or AMO-1618 (AMO) for inhibition of gibberellic acid (GA) biosynthesis were applied at anthesis to proximal grain positions of spikelets in the central region of main ears. Both phytohormones (IAA, GA) might contribute to control relations and storage capacities within and between spikelets. Two genotypes with different ear structure were used. After treatment plants were placed under different light and temperature conditions. — Relatively low light and temperature levels (growth chamber) depressed grain yield/ear remarkably by increased numbers of sterile florets mostly in distal positions. Treatments released distal florets from this inhibition and grain yields/ear increased. Under high temperature levels (glass-hall) grain yields/ear decreased as well, mostly by storage of smaller amounts of dry matter per grain. In interaction with the growth regulator the treatments favoured dry matter storage in distal grains even under these conditions, but the effects were combined with a further weight decrease in proximal grains. Similar treatment effects were found under nearly natural light- and temperature conditions (wire net-hall). More interactions with genotypes are discussed. Untersucht wurde die Bedeutung der Umwelt-bedingungen zwischen Anthese und Reife (Standorte: Drahthalle, Klimakammer, Ge-wächshaus) für die Effekte von Wirkstoffbe-handlungen an der S. Weizenähre auf deren Speicherfunktion. Einzelpflanzen von Geno-typen mit unterschiedlichem Ährenaufbau (Oskar, Kolibri) wurden in 3 Serien in Gefäß-kultur angezogen. Auf die 2 proximalen Blüt-chen von 6 Ährchen in der Zentralregion von Ähren I. Ordnung wurden bei Anthese die Wirkstoffe Chlorflurenolmethylester (CFM) bzw. AMO-1618 (AMO) aufgetragen. Beide Substanzen hemmen Wirkungen endogener Phytohormone (Auxine, Gibberelline), die vermutlich das Speichervermögen jüngerer, insbesondere distaler Speicherorte kontrollie-ren und auf diese Weise den Ährenertrag mit-bestimmen. Folgende Ergebnisse wurden festgestellt und diskutiert: — Im Vergleich zur Drahthalle niedriges Temperatur- und Lichtangebot (= Klimakammer) reduzierte den Kornertrag von Kontrollähren im Mittel auf rd. 70 % (Äh-renertrag/Drahthalle = 100). Ursache war primär der Ausfall distaler Blütchen als Speicherorte, die Kornzahl/Ähre nahm er-heblich ab. Diese kann u. a. als Hemmung infolge erhöhter Dominanz der proximalen Positionen in den Ährchen interpretiert werden. Mit wirkstoff- und sortenbeding-ten Abstufungen hoben die Applikationen die Hemmung distaler Positionen in be-grenztem Umfang auf, die Ährenerträge stiegen an. — Im Vergleich zur Drahthalle hohes Tempe-raturniveau (= Gewächshaus) reduzierte den Kornertrag von Kontrollähren im Mittel auf rd. 60 %. Vorrangige Ursache war hier der kleinere Speicherumfang in proximalen wie distalen Positionen aller Ähren-regionen, das TKG blieb erheblich gerin-ger. Insbesondere die CFM-Applikation führte zu einem weiteren Rückgang der Speicherung in proximalen Anlagen, der durch höhere Korngewichte in distalen nicht ausgeglichen werden konnte. Gleich-gerichtete Wirkstoffeffekte traten in der Drahthalle auf. — Die Wirkstoffeffekte hingen nicht nur von den Einlagerungsbedingungen, sondern auch vom genotypischen Aufbau des Spei-chersystems Ähre ab. Bei der Oskarähre, einem System, das durch hohe Kornzahl charakterisiert ist, zeichneten sich die Effekte schärfer ab als bei der Kolibriähre, einem System mit niedrigerer Kornzahl.
 
Article
Compensation capacity of wheat ears depending on temperature level during grain-filling period In order to investigate the compensation capacity, effects of sterilization treatments on dry matter storage within spikelets and florets of wheat ears, growing in different temperatures during grain-filling period were tested. Alternatively proximal or distal florets from 6 spikelets in the central region were removed at different stages. — Grain weight/ear remained 40% smaller in the high compared with the low temperature level. With high temperature sterilization of proximal florets allowed more additional florets in distal positions to develop grains than with low temperature. Beyond of this in both levels single grain weights in the basal and the apical region of the ear increased. Compensation effects, especially by additional grains decreased as later the treatments were done. Relatively the grain weight loss by sterilization was compensated to a higher degree in high than in low temperatures.
 
Article
N2O Emissions from True Meadows Dependent on Location and N Fertilization Agricultural production is thought to be a main anthropogenic emitter of nitrous oxide (N2O), which contributes to global warming and the destruction of the ozone layer. There is still considerable uncertainty about the amount of N2O emission, and the site-specific parameters that affect N2O emission. From October 1995 until March 1998 experiments were conducted at established field plots (true meadows) at three different sites, i.e. low mountain range (Eifel), lowland (Niederrhein), and moist meadows (Münsterland). Plots were fertilized with calcium ammonium nitrate (CAN) at nitrogen equivalents ranging from 0 to 360 kg N ha–1. N2O fluxes were measured throughout the whole year using the closed-chamber method. In addition, data on temperature, water-filled pore space and precipitation were collected. N2O emission rates (mg N2O-N ha–1 h–1) were highest either after fertilizer application or in winter during frost, depending on the experimental site and N dosage. The annual amount of N losses due to N2O emission was dependent on the experimental site and the type and dosage of fertilizer. Disregarding the 360 kg N ha–1 level of the CAN treatments, the N losses in this experiment were less than 1.5 kg N2O-N ha–1 yr–1. At low fertilizer dosage there was no reliable correlation between the amount of N that was applied and the amount of N2O that was emitted. However, with high fertilizer levels the N2O emissions increased gradually. Finally, N2O emissions were more influenced by the amount of CAN than by the site. Lachgas (N2O) ist ein klimarelevantes Spurengas, zu dessen anthropogener Entstehung landwirtschaftlich genutzte Böden in hohem Maße beitragen. Die Quellenstärken können derzeit jedoch nur annähernd geschätzt werden. Emissionsdaten aus Langzeituntersuchungen liegen bislang für die landwirtschaftliche Bodennutzung in Deutschland, insbesondere für Grünlandflächen, kaum vor. Auf Dauergrünland mit Schnittnutzung und der N-Düngung von 0 bis 360 kg N ha–1 a–1 mit Kalkammonsalpeter wurden daher von Oktober 1995 bis März 1998 auf einem Mittelgebirgsstandort in der Eifel, einem Niederungsstandort am Niederrhein und einem Feuchtwiesenstandort im westlichen Münsterland ganzjährig in ein- bis zweiwöchentlichen Abständen Lachgasemissionen gemessen. Folgende Ergebnisse können festgehalten werden: (1) Von der Höhe der N-Düngung ging eine gesicherte Wirkung auf die Entgasungsraten aus. Es bestand meist ein linearer Zusammenhang zwischen den N-Düngerstufen und der Höhe der N2O-Emissionsmengen. (2) N2O-Entgasungsmengen außerhalb der Bewirtschaftungsperiode erreichten je nach Standort und Versuchsjahr Anteile an den Jahresentgasungsmengen von 9 bis 65 %. (3) Die jährlichen N2O-Entgasungsmengen betrugen unter Berücksichtigung der Hintergrundemissionen umgerechnet 0,06 bis 1,1 % der jährlichen N-Düngermengen; damit liegen sie mindestens um die Hälfte niedriger als Werte in der vorliegenden Literatur.
 
Article
The effect of 0, 0.05 or 0.1 mm abscisic acid treatment on chilling tolerance and salicylic acid-related responses was investigated in young maize seedlings (Zea mays L., hybrid Norma). Although the pre-treatment of maize seedlings with abscisic acid slightly decreased the chlorophyll content, it also reduced the level of chilling injury caused by 6 days of cold treatment at 5 °C. Under normal growth conditions, increased levels of bound salicylic acid and of bound ortho-hydroxycinnamic acid were observed in the leaves during abscisic acid treatment. In the roots, abscisic acid did not affect the free and bound salicylic acid levels, but increased the amount of free and bound ortho-hydroxycinnamic acid. The activity of glutathione-S-transferase increased on the 3rd day of abscisic acid treatment, whereas it did not change when followed by cold stress, compared with the control leaves. In the roots, the activities of glutathione reductase, glutathione-S-transferase and ascorbate peroxidase increased during the abscisic acid treatment, and those of glutathione-S-transferase and ascorbate peroxidase were also stimulated when abscisic acid pre-treatment was followed by cold stress, compared with the control roots. Our results suggest that an overlap may exist between the abscisic acid-induced cold acclimation and the salicylic acid-related stress response.
 
Article
Spatial correlation analysis between weed occurrence and those of the previous year and abiotic soil properties by example of ivy-leaved speedwell (Veronica hederifolia L.) and nitrogen contentThe spatial dependence of the occurrence of Veronica hederifolia L. on the previous year and on the nitrogen content of the soil (0–30 cm) is characterized by cross correlograms. These are drawn by use of the correlation coefficient of Pearson's ρ and Kendall's τb. The results from cross correlograms are compared with the correlation coefficients at the same sampling location between the occurrence of the weed for 2 consecutive years running and also between the nitrogen content and the weed occurrence in the same year. With the help of the cross correlograms we found up to which distances the two variables correlate significantly. The correlation coefficient calculated between two variables at the same sampling point are not sufficient to characterize their spatial dependence. Kendall's τb, corrected for ties, as a nonparametric measure of correlation, leads in two cases to more significant dependencies than does Pearson's correlation coefficient.
 
Article
Male gametophyte development of eukaryotic plants in general and rice in particular is especially sensitive to drought. Water deficit during this stage inhibits microspore development resulting in male sterility. To elucidate the molecular mechanism of the phenomenon, a water deficit-induced experiment was conducted during anther development. Microscopic observations of anther cross-sections labelled with TdT-mediated dUTP nick-end labelling (TUNEL) indicated programmed cell death (PCD) signals after three consecutive days of water deficit. PCD is a biological process featured by the fragmentation of genomic DNA and plays an important role in plant reproduction. PCD is often concurrent with biochemical and physical changes in the cytoplasm, nucleus and plasma membrane of the cells. In this study, biochemical assays showed depletion of the adenosine triphosphate pool, increased concentration of hydrogen peroxide (ROS) and down-regulation of antioxidant transcripts in anthers. We argue that the interplay between PCD and oxidative stress in anthers might be a cause of pollen sterility in drought-stressed rice.
 
Article
Above optimal temperatures in cereals, when measured in thermal time units (°Cd) can lead to underprediction of developmental events by models, particularly when cereals are sown late in Mediterranean-type environments or grown under subtropical conditions. Our objective was to assess the effects of high temperatures on the length of the spikelet growth phase, the number of spikelet nodes per spike and level of spikelet abortion in spring barley (Hordeum vulgare L.). The spikelet growth phase (from the end of the spikelet initiation phase to anthesis) of three cultivars, ‘Bandulla’, ‘Schooner’ and ‘Weeah’ was subjected to two temperature regimes. In the first of two sowings, the mean daily maximum temperature for one regime was 24 °C (maintained for 6 h daily) and the mean daily minimum was 8 °C (24/8 °C). The second temperature regime was 27/17 °C. Corresponding temperatures for the second sowing, which was subjected to slightly longer photoperiods, were 26/8 °C and 26/17°C, respectively. The duration of the spikelet growth phase was longer for 27/17 °C than for 24/8 °C in the first sowing when measured in calendar time (d). In the second sowing, the duration of the spikelet growth phase was slightly shorter under the higher temperature regime (d). The duration of the spikelet growth phase (in°Cd) was greatly increased by the higher temperature treatment in both sowings. In the first sowing, the percentage of aborted spikelets was greater at HT than at LT for Bandulla and Weeah at both sowing times and the duration of the spikelet growth phase increased with higher night temperatures, suggesting that length of the spikelet growth phase was not the sole factor responsible for the proportion of aborted spikelets.
 
Article
Selection criteria for drought tolerance would be helpful tools for wheat breeding programmes. To assess the usefulness of some morphological traits above the flag leaf node as indicators of yield and the susceptibility index (SI) of Fischer and Maurer, 10 durum wheat genotypes were used in experiments conducted under two water regimes at two latitudes in Spain during 3 years. Morphological traits were measured at anthesis, and yield, yield components and quality traits were evaluated at ripening. Principal components analysis showed associations between morphological traits and yield, yield components and quality, most of them caused by differences between environments. Peduncle weight, spike weight and length and awn length were significantly related to SI within environments. Spike and peduncle weight were the traits more related to yield and SI in all the experiments together and in the rainfed sites, while in the irrigated sites spike length was better. The spike weight and length were negatively associated with SI, while peduncle weight was positively associated to SI. Genotype means across all experiments were associated with SI values. These morphological traits could be selection criteria in breeding programmes to obtain varieties with good yield stability. The genetic variability found suggests opportunity for selection.
 
Article
Soya bean is often grown in regions prone to periodic flooding, thus selecting cultivars that maintain production under waterlogged conditions is desirable. An experiment involving flooded soya beans was planted in southern Florida to examine (1) stem and leaf growth; (2) morphological adaptations; and (3) the relationship between early-season and late-season flood tolerance in flooded soya beans. Eleven soya bean genotypes previously defined as tolerant or sensitive to flooding were subjected to three treatments at 21 days after sowing (DAS): (1) no flood, (2) 2-week flood and (3) 4-week flood. All plants were harvested 49 DAS. Flooded plants exhibited lower stem dry weights but greater partitioning to the stem. Non-flood treatments had greater leaf dry weight, leaf area and partitioning to leaves than flooded plants. There were positive correlations of genotype stem dry weight and leaf dry weight to early-season flood tolerance but stem partitioning was negatively correlated with early-season flood tolerance. Genotypic rankings of early-season flood tolerance in this study were not correlated with earlier studies basing flood tolerance on seed yield. Our study highlights the range of soya bean morphological adaptations in response to flood. However, our results indicate that early-season screening may not be an accurate predictor of soya bean genotypic response to late-season flood.
 
Article
Experiments conducted m a phytotron on three rice varieties of different salinity tolerance revealed an increase in the content of endogenous abscisic acid (ABA) with increasing NaCl salinity in IR20 (semi salt-tolerant), but in Pokkali (salt-tolerant) and IR28 (salt-sensitive) the increase in ABA content was marginal. Under sahnity stress, in general, 5 weekly sprayings of ABA (10-4 mol L-1) decreased Na and K concentrations in the shoot to the extent of 29.5 % and 3.3 %, respectively. However, ABA application significantly improved the K/Na ratio as well as the chlorophyll fluorescence decrease ratio (Rfd, indicator for potential photosynthetic activity), the number of green leaves per plant and the shoot dry weight. The response of IR20 and IR28 to ABA application was significantly better than that of Pokkali. Increasing salinity caused marked nutrient imbalances, decreased Rfd values and shoot dry weight. The results are discussed in relation to possible mechanism of salinity tolerance.
 
Article
A few rice cultivars with super high-yielding potential have successfully been released. However, little is known about the physiological mechanisms underlying the formation of super high yield in rice. Here, we report changes of cytokinin (zeatin + zeatin riboside, ZR) and abscisic acid (ABA) contents in roots and leaves during grain filling and their relation to declining photosynthesis function of leaves in super high-yielding rice cv. Xieyou 9308 and standard rice cv. Shanyou 63, as a control. ZR contents in roots and leaves decreased in a time-dependent manner, while their ABA contents were relatively stable at earlier grain filling stage and rapidly increased at later grain filling stage in both cultivars. A rapid decrease in ZR content and a rapid increase in ABA content were observed earlier in roots than in leaves for both cultivars. Declining instantaneous photosynthesis rate (IAPS) of leaves in both cultivars coincided with decreasing ZR contents and increasing ABA contents in both roots and leaves. Leaves with 6-benzyl aminopurine (6-BA) treatment exhibited increased IAPS and extended active photosynthesis duration (APD), and the result was reversed in leaves with ABA treatment. A rapid decrease in ZR contents and a rapid increase in ABA contents of roots and leaves in Xieyou 9308 obviously lagged behind those in Shanyou 63. These results suggest that decreased ZR content and increased ABA content in roots cause the decline of photosynthetic function during grain filling stage. The highly efficient photosynthetic function of Xieyou 9308 is due to the delayed change of ZR and ABA contents in its roots.
 
Article
Two wheat genotypes differing in water stress sensitivity (C306, relatively tolerant; HD2329, relatively susceptible) were water stressed during early grain filling by withholding water for 7 days at watery-ripe (WR) stage and examined for water status, abscisic acid (ABA) and osmolytes in grains as well as in flag leaf (FL). Both the genotypes differed significantly from each other in endogenous levels of ABA, proline, glycine betaine, total soluble sugars, reducing sugars, sucrose and potassium. The tolerant genotype showed higher content of ABA, proline, glycine betaine, total sugars, reducing sugars and had higher water content in its FL and grains than the susceptible genotype, which contained more of glycine beatine and potassium but had lower ABA and water content in its FL and grains. Although carbohydrates constituted the major amount of all the solutes, proline and glycine betaine increased manifold during stress. Exogenous application of 2 μm ABA at 5 days after anthesis to FL of stressed plants increased the endogenous content of ABA, accelerated the accumulation of osmolytes, improved the water status of FL and grains that resulted in higher grain weight, especially in the susceptible genotype. Differential response of contrasting wheat genotypes to water stress may be governed by ABA-dependent solute accumulation in grains and FL.
 
Article
The protective effect of a synthetic terpenoid analog of abscisic acid (ABA), coded LAB 173711, on transplant shock in rice was investigated under field conditions. Rice seedlings (Fujisaka 5 and IR 20) were taken from a seed bed and their roots were immersed in aqueous solutions of the growth regulators for 24 h. Afterwards they were drought-stressed for 3 or 6 h by exposing them to direct sunlight before they were transplanted to the field. A pretreatment with either LAB 173711 alone or in combination with the growth retardant tetcyclacis reduced the loss of water during the exposure to sunlight, increased the percentage of survival of the seedlings in the field, and increased the percentage of grain filling of the plants which had survived. The combined application of growth regulators was most effective and may be useful for minimizing transplant shock in rice and other crops.
 
Top-cited authors
Muhammad Farooq
  • Sultan Qaboos University
Shahzad M. A. Basra
  • University of Agriculture Faisalabad
Sven-Erik Jacobsen
  • Quinoa Quality ApS
Raj Kumar Sairam
  • Indian Agricultural Research Institute
Mumtaz Cheema
  • Memorial University of Newfoundland