Article

Effects of Sink Removal on Photosynthesis and Senescence in Leaves of Soybean (Glycine max L.) Plants

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Photosynthetic rate, ribulose 1,5-bisphosphate carboxylase activity, specific leaf weight, and leaf concentrations of carbohydrates, proteins, chlorophyll, and inorganic phosphate were determined periodically from midbloom until maturity in leaves of soybean plants (Glycine max L., var. Hodgson) from which reproductive and vegetative sinks had been removed 32 hours before measurement, or continuously since midbloom.Leaf photosynthesis, measured in the top of the canopy, was partially inhibited by both sink removal treatments. This inhibition was of constant magnitude from midbloom until maturity.Leaf photosynthesis in the top of the canopy declined from midbloom until maturity in the control as well as in the desinked plants. The decline in photosynthesis was gradual at first, but later became more abrupt. The photosynthetic decline was equally evident in the yellowing leaves of control plants and in the dark green leaves of the continuously desinked plants.Neither the inhibition of photosynthesis by sink removal nor the decline in photosynthetic rate with time was clearly related to any of the measured traits.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... beans that set relatively few pods stay green (Burke et al., 1984) and main tain their Ny-fixing capacity longer (Imsande and Ralston, 1982). Even in soybean, where depodding may prevent rapid death, it may not prevent the decline in photosynthesis and other parameters generally associated with senescence (Woodward and Rawson, 1976;Mondal et al., 1978;Section V,B). For wheat, head removal retarded some, but not all, of the changes associated with the senescence syndrome (King et al., 1967;Feller, 1979;Patterson and Brun, 1980). ...
... Under a noninductive photoperiod, soybean plants can be induced to reach a height of more than 7 m and to last more than 15 months (Nooden, 1980b). The soybean case presents a particularly interesting problem, because defruiting does not reinstate the shoot elonga tion, although it may promote root growth somewhat (Loong and Lenz, 1974;Derman et al., 1978;Sutton, 1983) or leaf and stem thickening (Lenz and Williams, 1973;Mondal et al., 1978;. Thus, the flower ing signal (or some concurrent) signal and not some influence from the pods inhibits vegetative growth (Nooden, 1980b. ...
... They may involve parallel processes that are not tightly coupled rather than a single sequence of changes . Thus, for example, there are differences in the relative timing of the declines in chlorophyll, photosynthesis, and total nitrogen in the leaves of senescing soybean plants under different conditions (Kumura and Naniwa, 1965;Woodward and Rawson, 1976;Mondal et al., 1978;Wittenbach et al., 1980;Okatan et al., 1981;Secor et al., 1983). In any case, one can readily point to the decrease in photosynthesis as an important component of monocarpic senescence. ...
Chapter
This chapter discusses causes of monocarpic senescence and senescence in polycarpic plants and clones. Whole plant senescence is viewed primarily in terms of leaf senescence and it is measured mainly through chloroplastic parameters such as chlorophyll loss and decreased photosynthesis. In monocarpic plants where senescence and death closely follow reproductive development, the senescence (monocarpic senescence) is often controlled by the developing reproductive structures. In these cases, removal of the reproductive structures or prevention of their development usually prolongs the life of the plant. Monocarpic plants cease their vegetative growth fairly abruptly early in their reproductive phase. Conversely, the perennial polycarpic pattern requires continued vegetative growth. This prominent shift (diversion) in growth-related allocation of resources in monocarpy seems to be part of a reproductive strategy that optimizes reproductive output for the plants. This diversion/withdrawal is often quite prominent that leads to monocarpic senescence.
... Studies have suggested factors that promote GSD, such as excessively wet soil conditions during the reproductive period (Sato et al., 2007), drought at the flowering and pod set periods after excessively wet conditions during initial growth (Tsujimoto et al., 2006), high temperature during the reproductive period (Mochizuki et al., 2005), pest attacks at the pod set and filling stages (Boethel et al., 2000), and diseases occurrence (Takehara et al., 2016). Depodding at the pod set and filling stages has also been used as an experimental treatment to promote delayed senescence of leaves and stems including GSD (Crafts-Brandner & Egli, 1987;Crafts-Brandner et al., 1984;Egli & Bruening, 2006;Htwe et al., 2011;Leopold et al., 1959;Mondal et al., 1978;Wittenbach, 1982). The common feature behind these factors or treatments is thought to be a decrease in the number of pods due to some type of stress during the reproductive phase. ...
... Depodding is the most frequently used treatment in research of leaf and stem senescence, including GSD research (Crafts-Brandner & Egli, 1987;Crafts-Brandner et al., 1984;Egli & Bruening, 2006;Htwe et al., 2011;Leopold et al., 1959;Mondal et al., 1978;Wittenbach, 1982), which decreases sink size and then increases the source-sink ratio. In this study, a novel approach was employed to increase the source-sink ratio. ...
... These results suggest that increased light availability at R5 stage promotes GSD, probably by enhancing the source relative to the sink. This finding just reconfirms the results of previous studies in which the sink was reduced in order to promote GSD (Crafts-Brandner & Egli, 1987;Crafts-Brandner et al., 1984;Egli & Bruening, 2006;Htwe et al., 2011;Leopold et al., 1959;Mondal et al., 1978;Wittenbach, 1982). However, to our knowledge, it has never been reported that the enhanced source also promoted GSD. ...
Article
Full-text available
Green stem disorder (GSD) in soybean (Glycine max (L.) Merrill) retains green stems and leaves as the pods mature, thereby reducing the harvest efficiency and impairing seed quality. In order to elucidate the causes of GSD, the factors that promote GSD need to be identified. In our experiments, we adjusted plant density at the developmental growth stage R1 (the beginning of flowering) or at R5 (the beginning of seed filling), from dense (22.2 plants m–2) to sparse (5.56 plants m–2) by thinning. We found that GSD occurrence was increased when plant density was changed, compared to the treatments that were maintained under either dense or sparse conditions. GSD was promoted more strongly when thinning was conducted at R5 than at R1 stage. Shading equipment surrounding plants, except for their upper-most leaves, was implemented to determine the association of shading and GSD. The results of the shade experiment revealed that GSD occurrence generally increased in treatments subjected to shade removal, compared to those that were shaded until R8 stage (full maturity) or never shaded since the time of sowing. GSD was strongly promoted by shade removal at R5 than at R1 stage. The shading results coincide with the results of the plant density experiment, indicating that an increase in light availability enhances source activity relative to sink at R5 stage, thereby promoting GSD occurrence in soybean. Thinning is expected to be used as an easy experimental method to create GSD for research purpose.
... During the first 42 days after emergence, net assimilation rate was greater in unshaded plants than in those shaded at 50 or 70% (Fig. 11). This may be attributed to the high sink capacity of roots in unshaded plants, which may increase the photosynthetic efficiency of plants, since there appears to be a relationship between sink capacity and assimilate production (Mondal et al., 1978;Hendrix, 1995). At the end of plant development, plants at 70% shading showed the greatest net assimilation rates, probably due to delay in leaf senescence, and production of new leaves even at the end of plant cycle in shaded treatments. ...
Article
Full-text available
Wrinkled grass (Ischaemum rugosum Salisb.) is one of the most important weeds in irrigated rice in Maranhao, with infested fields increasing each season. The experiment was conducted in pots to study the effects of shading (0, 50 and 70%) on wrinkled grass growth. Plants were harvested at seven days after emergence (DAE), and from 14 to 112 DAE at 14-day intervals. They were separated in culms, leaves and roots, dried, weighed, and leaf area measured. Dry matter (DM) accumulation of culms, leaves and roots was reduced by shading. In roots, dry matter accumulation diminished as levels of shading increased. A sharp decline in root dry matter accumulation was observed after the beginning of flowering in unshaded plants. Leaf area, however, was greater in plants grown at 50% shading than in those that were shaded at 0 or 70%. Relative growth rate (Rw) was greater in shaded than in unshaded plants. The contrary was true for net assimilation rate (Ea). At the end of the plant cycle, however, the net assimilation rate was greater in plants shaded at 70% than in those shaded at 0 or 50%. It was concluded that there was an effect of shading on sink preference. At full sunlight the roots were the preferred sink during the vegetative phase, whereas the culms appear to be the primary sinks during the reproductive period. In shaded environments the culms and leaves were the preferred sinks. Leaf thickness was lower in plants cultivated at high levels of shading than in sunniest plants receiving more light.
... leaves in developing crowns and sometimes augmented with leaves of slips (Bartholomew and Malezieux, 1994;Marler, 2011). The sink activity due to the presence of fruit generally increased net photosynthesis of leaves near the fruit (DeJong, 1986;Lenz, 1979;Mondal et al., 1978;Schaffer et al., 1986Schaffer et al., , 1987. When fruit was about six months old, about four months after flowering has occurred, changes begun to be observed. ...
Article
The experiment was carried out in a greenhouse, located in Tehran city, Iran. The objectives of this study was to evaluate the effects of fertilizer and acidic soil on the foliar and radicular growth of micropropagated plantlets of the pineapple cv. Merr (Ananas comosus L.). We evaluated the growth of that genotype in five different ages of acclimatizing: 1, 2, 3, 4, 5 and 6 months in greenhouse. The hardening of plantlets increased length of shoot, leaf length and leaf number and slip production, accelerated flowering and fruit maturity, caused uniform flowering and fruit ripening, and had no effect on sucker development. When hardening plantlets were at least 60 to 70 cm tall and 10 to 12 months old, an inflorescence bud was observed to form in the center of the leaves. Flowers (light red in color) opened row by row over a period of about two weeks. When fruits were about six months old, about four months after flowering has occurred, these changes were observed. The color of the shell changed from green to rich gold. When the fruit was golden half way up, it could be picked and eaten. The color change of the shell occurred first at the bottom of the fruit and moved upwards. During this change, the fruit became sweeter and the color of the flesh changed from white to yellow.
... This agrees with the work of Shibbles et al. (1981) that plants are affected by various manipulation that alters the source sink ratio including deppoding, partial or total shading of the foliage, foliage removal, light and carbon dioxide enrichment. Mondel et al. (1978) and Selter et al. (1980) reported that defoliation alters hormone balance, starch, sugar, protein and chlorophyll concentration of source leaves as well as stomata resistance and senescence rate. The effect of defoliation depends, however on the growth at which defoliation takes place. ...
Article
Full-text available
Field experiments were conducted in 2006 and 2007 on the experimental farm of the Institute for Agricultural Research, Ahmadu Bello University, Samaru, Zaria to determine the effect of stage and intensity of defoliation on the performance of vegetable cowpea. The treatments were laid out in a randomized complete block design replicated three times. The treatment consisted of factorial combination of three growth stages (vegetative, flowering and podding) and five defoliation intensity (0, 25, 50, 75 and 100). Artificial defoliation was carried out at each of the stages at different intensities. Defoliation for vegetative, flowering and podding were carried out at 5, 7 and 9 weeks after sowing respectively. Cowpea defoliated at the early stages just prior to podding significantly (p < < < < 0.05) reduced both growth and developmental characters. Also, the yield and yield components were significantly reduced by early defoliation. The intensity of defoliation significantly affected the growth and development of cowpea and the yield loss increased as the percentage of defoliation was higher. The interaction between stage and intensity of defoliation was significant for pod yield and shows that defoliating up to 50% at vegetative and flowering stages was detrimental to yield of vegetable cowpea.
... For example, removal of developing pods (soybean plants), which decreases sink capacity, was shown to result in accumulation of major photosynthetic carbohydrate (sucrose) in leaf, decrease in leaf photosynthetic rate, and decrease in Rubisco activity of leaf extract [20]. Data from other studies conducting removal of floral organs or petiole girdling, which decreases sink capacity, or continuous exposure to light, which reduces sink capacity by increasing photosynthetic source capacity, suggest that a decrease in stomatal conductance or Rubisco activity or Rubisco content in leaf, or both decreases in Rubisco activity and Rubisco content in leaf are responsible for the reduced sink capacityinduced decrease in leaf photosynthetic rate [21][22][23][24][25][26][27][28]. In potato and Arabidopsis, continuous exposure to light has been shown to accelerate expressions of photosynthetic genes, pigments and proteins, and subsequent declines of the expressions [29,30]. ...
Article
Full-text available
Despite the wide uses of potted plants, information on how pot size affects plant photosynthetic matter production is still considerably limited. This study investigated with soybean plants how transplantation into larger pots affects various characteristics related to photosynthetic matter production. The transplantation was analyzed to increase leaf photosynthetic rate, transpiration rate, and stomatal conductance without affecting significantly leaf intercellular CO2 concentration, implicating that the transplantation induced equal increases in the rate of CO2 diffusion via leaf stomata and the rate of CO2 fixation in leaf photosynthetic cells. Analyses of Rubisco activity and contents of a substrate (ribulose-1,5-bisphosphate (RuBP)) for Rubisco and total protein in leaf suggested that an increase in leaf Rubisco activity, which is likely to result from an increase in leaf Rubisco content, could contribute to the transplantation-induced increase in leaf photosynthetic rate. Analyses of leaf major photosynthetic carbohydrates and dry weights of source and sink organs revealed that transplantation increased plant sink capacity that uses leaf starch, inducing a decrease in leaf starch content and an increase in whole plant growth, particularly, growth of sink organs. Previously, in the same soybean species, it was demonstrated that negative correlation exists between leaf starch content and photosynthetic rate and that accumulation of starch in leaf decreases the rate of CO2 diffusion within leaf. Thus, it was suggested that the transplantation-induced increase in plant sink capacity decreasing leaf starch content could cause the transplantation-induced increase in leaf photosynthetic rate by inducing an increase in the rate of CO2 diffusion within leaf and thereby substantiating an increase in leaf Rubisco activity in vivo. It was therefore concluded that transplantation of soybean plants into larger pots attempted in this study increased the plant photosynthetic matter production by increasing mainly sink capacity that uses leaf starch for whole plant growth, particularly, growth of sink organs.
... Following that, N remobilization is triggered by the demand of developing kernels, and it is reasonable to hypothesize that higher grain number per area might accelerate N remobilization and thus shorten leaf senescence duration during the grain filling period. Studies involving source :sink manipulations have clearly shown that source reduction accelerated senescence while sink reduction delayed senescence in different species including wheat (Mondal et al., 1978;Tollenaar and Daynard, 1982;Zhenlin et al., 1998;Rajcan and Tollenaar, 1999a). Nevertheless, contradictory results may temper this suggestion, and calls for a more exhaustive understanding of the relationship between leaf senescence and crop source : sink ratio (Dreccer et al., 1997;Mi et al., 2000). ...
Article
Full-text available
Grain yield (GY) and grain protein concentration (GPC) are two major targets in wheat breeding programs as these traits contribute to the economic value of the wheat crop. Unfortunately, their simultaneous improvement is hampered by the genetic negative GPC-GY relationship. It has been shown that the deviation to this relationship ("Grain Protein Deviation", GPD) has a genetic basis and might be useful to shift this negative relationship but its biological bases remain unclear. GPD was shown to be mainly related to the genetic variability for post-anthesis nitrogen (N) uptake (PANU) in the North-West European agro-climatic conditions. We proposed that the genetic variability for the access to N in the soil (root architecture and functioning) or for the regulation of PANU by the plant N status (N transport and assimilation) could explain GPD. As delaying leaf senescence during the post-anthesis period might result in increasing PANU, we analysed the genetic determinants of the phenotypic relationships between leaf senescence duration after anthesis and GPC or GY using data obtained on a wheat mapping population grown in a large mutli-environment trial network. A positive association was found between leaf senescence duration and GPC or GY depending onthe environment. We suggested that the impact of delaying leaf senescence after anthesis on GY or GPC might be modulated by the N availability during the post-anthesis period and would lead to modify the GPC-GY relationship depending on the considered environments. Finally, data obtained on three connected mapping populations grown in a large mutli-environment trial network were used to suggest by meta-QTL analysis potential genomic regions possibly useful in wheat breeding to improve GPC without reducing GY. This put forward genomic regions located on the 2A and 3B chromosomes as potentially interesting targets to improve GPC. In particular, the region on the 2A might be related to a chloroplastic glutamine synthetase gene previously shown to be associated with genetic variability for GPC in bread wheat.
... In addition, the appearance of seeds (sing organs) may lead to a depravation of water relations, a depletion of available nutrients, or may produce several hormonal signals which regulate senescence (e.g. ethylene), and the removal of sink organs will slow down this process thus delay senescence (Mondal et al. 1978). While in other studies, researchers found that removal of sink organs did not influence the process of senescence, but rather altered the partitioning of plant constituents and the visual manifestations of senescence (Crafts-Brandner et al. 1984). ...
Article
Full-text available
Leaf senescence can be described as the dismantling of cellular components during the terminal stage in the development of plant organs and tissues. In order to determine the leaf senescence process when stem girdling and leaf removal both exist. An experiment was carried out in Alhagi sparsifolia, which grew in the Cele oasis-desert transitional zone with the treatment of control (CK), phloem girdling (PG), leaf removal (LR), and combined girdling and removal (GR). Some parameters related to leaf senescence were measured at the 1st and 30th day post-girdling. The results showed that after PG and GR, leaf soluble sugar content, starch content, abscisic acid content, proline content, and malondialdehyde content increased substantially and leaf photosynthetic rate, stomatal conductance, transpiration rate, photosynthetic pigment content, and water potential decreased substantially compared with CK. It also changed much more in PG leaves than in GR leaves. The change in LR leaves was opposite to that of PG and GR leaves, but the change was rather slight. The result of the present work implied that senescence of leaves treated with PG greatly accelerates, and the accumulation of carbohydrates and ABA in leaves is probably the main reason for this. Separate LR could play a role in delaying leaf senescence in plants; however, this delay effect was not obvious. Nevertheless, partial removal of leaves led to a significant compensation of girdling effects, i.e., senescence will be delayed significantly in girdled leaves when treated with partial LR.
... The results of this study agrees with statement of Shibbles et al. (1987) that plants are affected by various manipulation that alter the source-sink ratio including depodding, partial or total shading of the foliage, foliage removal, light and carbon dioxide enrichment. Mondal et al. (1978) and Selter et al. (1980) reported that defoliation alters hormone balance, starch, sugar, protein and chlorophyll concentration of source leaves as well as stomatal resistance and senescence rate. The effect of defoliation depends, however, on the foliar surface area eliminated and on the growth at which this takes place (Muro et al., 2001). ...
Article
Full-text available
The defoliation of cowpea in the vegetative stage significantly decreased grain yield and profitability, while percent intensity of the defoliation provided the highest grain yield and profit in the cowpea production.
... Sinclair and de Wit (1976) theorized that the N demand for soybean and other high protein crops could not be met by N accumulation alone and that remobilization and translocation of N and proteins from vegetative tissues must occur to support seed growth. As this pool of N and proteins was depleted (Boote et al., 1978;Borst and Thatcher, 1931;Egli et al., 1978a;Hanway and Weber, 1971b), photosynthetic rates also declined (Boote et al., 1978;Lugg and Sinclair, 1981;Mondal et al., 1978;Sesay and Shibles, 1980;Sinclair, 1980;Wittenbach et al., 1980). Eventually, the photosynthetic apparatus loses functional integrity along with other physiological processes, thereby ending the EFP and limiting final seed yield. ...
... Sterile and other mutants of Arabidop sis (Arabidopsis thaliana) with delayed senescence did not exhibit prolonged leaf life, but did show an extended production of leaves and flowering stalks [15]. Following soybean pod removal, the leaves did not show the dramatic visual yellowing associated with senescence, but function, as measured in terms of the rate of photosynthesis or the activity of Rubisco, was inhibited [16][17][18]. Delayed senescence in "stay green" genotypes of sorghum did appear to result in prolonged photosynthetic capability, but this seemed to be most closely correlated with greater nitrogen assimilation during the grain filling period [19]. ...
Article
Full-text available
After the flowering of an annual plant, the whole plant will senesce and die. For the process to go to completion, this monocarpic senescence must include three coordinated processes, which have not previously been considered as a total syndrome: (1) the arrest of growth and senescence of the shoot apical meristem; (2) senescence of the leaves; and (3) the suppression of axillary bud growth. Concurrently there is a shift in resource allocation from continued vegetative growth to reproductive growth, combined with a withdrawal of nutrients, especially nitrogen compounds, from the leaves and the transfer of these nutrients to the developing seeds. The start of the senescence process is caused by a shift, almost certainly in gene expression, very early in the reproductive phase. Continuation of the resource transfer and senescence of the vegetative plant involves hormonal regulation and continued changes in gene expression. Each of these processes is examined, especially with reference to the transfer of resources from vegetative to reproductive growth.
... The results of this study agrees with statement of Shibbles et al. (1987) that plants are affected by various manipulation that alter the source-sink ratio including depodding, partial or total shading of the foliage, foliage removal, light and carbon dioxide enrichment. Mondal et al. (1978) and Selter et al. (1980) reported that defoliation alters hormone balance, starch, sugar, protein and chlorophyll concentration of source leaves as well as stomatal resistance and senescence rate. The effect of defoliation depends, however, on the foliar surface area eliminated and on the growth at which this takes place (Muro et al., 2001). ...
Article
Full-text available
The defoliation of cowpea in the vegetative stage significantly decreased grain yield and profitability, while percent intensity of the defoliation provided the highest grain yield and profit in the cowpea production.
... Removal of sinks (e.g., young, developing leaves and/or fruits) as consumers of photosynthate often results in decreased rates of photosynthesis in a plant's source leaves (Cheng et al. 2009 ;Duan et al. 2008 ;Mondal et al. 1978 ;Myers et al. 1999 ;Wünsche et al. 2005 ), except for cases with apparent intermediate carbohydrate pools that can buffer responses (Murchie et al. 2002 ;Nakano et al. 1995 ). For example, severe and highly signifi cant depressions in photosynthesis rates were observed in leaves of peach tree branches from which all the fruits were removed (fi lled squares) compared to branches with a single peach (open circles; Fig. 23.1a ). ...
Chapter
Products of photosynthesis (reduced carbon, typically in the form of sugars), synthesized by a plant’s mature source leaves, are exported to the plant’s sinks for growth, storage, and/or maintenance respiration. When the rate of sugar production in source leaves exceeds the rate of export (often as a result of insufficient sink activity), sugars and starch accumulate in source leaves. In a feedback response, levels of messenger RNAs, coding for various photosynthetic proteins, of source leaves are repressed along with the levels of these proteins. Furthermore, the overall capacity for photosynthetic CO2 fixation is also decreased. Consequently, these source leaves with decreased rates of photosynthetic electron transport utilize a lessened fraction of the light they absorb for photochemistry, and should thus increase the level of thermal dissipation of (excess) absorbed light. Thermal dissipation can be assessed as increased non-photochemical quenching (NPQ) of chlorophyll fluorescence, as well as decreased intrinsic photosystem II (PS II) efficiency, the ratio of variable to maximal chlorophyll fluorescence Fv/Fm (in darkness) or F v′/F m′ (in the light) (Fv being Fm – Fo; where v stands for variable, m for maximum, and o for minimum). Greater source activity relative to sink activity within the whole plant, resulting in starch and/or sugar accumulation, indeed leads to increases in thermal dissipation and in the concentration of zeaxanthin, a xanthophyll involved in thermal dissipation. Under severe conditions, high zeaxanthin levels, high thermal energy dissipation, and low PS II efficiency in source leaves become locked-in as part of a state of chronic photoinhibition associated with high foliar levels of sugar and starch. A correlation between photoinhibition and foliar non-structural carbohydrate accumulation is a common occurrence. In this chapter, we discuss various potential underlying causes for this correlation, including the possibility that reduced growth of plants under stress conditions leads to sink limitation, foliar starch and sugar accumulation, and photoinhibition as a manifestation of photosynthetic repression under excess light.
... via photosynthetic repression in response to removal of fruit and other sinks (e.g. [7,[10][11][12]). Foliar sugar and/or starch accumulation are typically observed under either limiting carbon export at the leaf level or limiting plant sink strength [13]. ...
Article
Full-text available
This review focuses on feedback pathways that serve to match plant energy acquisition with plant energy utilization, and thereby aid in the optimization of chloroplast and whole-plant function in a given environment. First, the role of source-sink signalling in adjusting photosynthetic capacity (light harvesting, photochemistry and carbon fixation) to meet whole-plant carbohydrate demand is briefly reviewed. Contrasting overall outcomes, i.e. increased plant growth versus plant growth arrest, are described and related to respective contrasting environments that either do or do not present opportunities for plant growth. Next, new insights into chloroplast-generated oxidative signals, and their modulation by specific components of the chloroplast's photoprotective network, are reviewed with respect to their ability to block foliar phloem-loading complexes, and, thereby, affect both plant growth and plant biotic defences. Lastly, carbon export capacity is described as a newly identified tuning point that has been subjected to the evolution of differential responses in plant varieties (ecotypes) and species from different geographical origins with contrasting environmental challenges.
... It is thus conceivable that, for the Swedish ecotype that evolved in a cooler and moister climate, it is advantageous to link development of more tracheids to the development of more phloem in response to growth at cool temperatures rather than to warm temperatures rarely experienced by this winter annual in a high-latitude environment. Removal of sinks (like developing fruit or developing leaves) as destinations for sugars produced by photosynthetically active source leaves results in decreased photosynthesis rates of source leaves (Mondal et al., 1978; Myers et al., 1999; Wünsche et al., 2005; Duan et al., 2008 ). In addition, downregulation of components of the photosynthetic apparatus, due to feedback inhibition by products of photosynthesis accumulating in the leaf, was elegantly demonstrated through cold-girdling (lowering the temperature of the phloem to slow the transport of sugars out of the leaf) of individual leaf petioles (Krapp et al., 1993; Krapp and Stitt, 1995). ...
Article
Full-text available
Through microscopic analysis of veins and assessment of light- and CO2-saturated rates of photosynthetic oxygen evolution, we investigated the relationship between minor loading vein anatomy and photosynthesis of mature leaves in three ecotypes of Arabidopsis thaliana grown under four different combinations of temperature and photon flux density (PFD). All three ecotypes exhibited greater numbers and cross-sectional area of phloem cells as well as higher photosynthesis rates in response to higher PFD and especially lower temperature. The Swedish ecotype exhibited the strongest response to these conditions, the Italian ecotype the weakest response, and the Col-0 ecotype exhibited an intermediate response. Among all three ecotypes, strong linear relationships were found between light- and CO2-saturated rates of photosynthetic oxygen evolution and the number and area of either sieve elements or of companion and phloem parenchyma cells in foliar minor loading veins, with the Swedish ecotype showing the highest number of cells in minor loading veins (and largest minor veins) coupled with unprecedented high rates of photosynthesis. Linear, albeit less significant, relationships were also observed between number and cross-sectional area of tracheids per minor loading vein versus light- and CO2-saturated rates of photosynthetic oxygen evolution. We suggest that sugar distribution infrastructure in the phloem is co-regulated with other features that set the upper limit for photosynthesis. The apparent genetic differences among Arabidopsis ecotypes should allow for future identification of the gene(s) involved in augmenting sugar-loading and -transporting phloem cells and maximal rates of photosynthesis.
... There have been many studies which have demonstrated the influence of the requirement of carbon for growth on the rates of net photosynthesis, but these have generally been with plants that have been manipulated to put source and sink out of balance (e.g. King et al. 1967;Mondal et al. 1978). Our results imply that, in plants that develop normally, leaf area and plant size are more subject to change than are rates of photosynthesis per unit leaf area. ...
Article
Full-text available
Net photosynthesis, dark respiration and the response to photon flux density were measured on cotton leaves grown in a glasshouse. Leaves at four positions on the plant were examined from their unfolding until 70 days later. Photosynthesis and transpiration per unit of leaf area were unaffected by leaf position and, in all leaves, peak photosynthesis of about 110 ng CO2 cm-2 s-1 was attained 13-15 days after leaf unfolding, when the leaf was 75-90% of maximum area. Photosynthesis was maintained at this rate for only 12 days before declining linearly to values 20% of the maximum when leaves were 70 days old. Transpiration followed a similar pattern reaching a maximum of about 13 µg H2O cm-2 s-1 at 2 kPa vapour pressure deficit (VPD) at 13 days. Stomatal and internal conductances changed in parallel as leaves aged, with the consequence that internal CO2 concentration and water use efficiency remainedessentially constant at 220µll-1 and 16.8 ng CO2 (µg H2O kPa VPD-1)-1 respectively. Youngest and oldest leaves saturated at lowest light levels (400-800 pE m-2 s-1) while 16-18- day-old leaves had light saturation at 1100 µE m-2 s-1. The initial slope of the light response curves increased as leaves expanded up to 10 days age then remained constant at 0.25 ng CO2 cm-2 (pE m-2)-1. Dark respiration reached a maximum of 1.5 ng CO2 mg-1 s-1 5 days after leaf unfolding, when leaf dry weight was increasing most rapidly. The relationship between the consistent pattern of gas exchange with age and the pattern of morphological development is discussed, along with internal factors associated with age-dependent photosynthesis.
... Niinemets 2004;Williams and Phillips 1980), and/ or ontogenetic declines in both RuBP carboxylase activity and/ or chloroplast numbers (e.g. Ford and Shibles 1988;Mondal et al. 1978). ...
Article
Full-text available
Aims Phenotypic trait variation across environmental gradients and through plant ontogeny is critical in driving ecological processes, especially in agroecosystems where single genotypes exist in high abundances. While variability in root traits plays a key role in belowground processes, few studies have identified the presence of an intraspecific “Root Economics Spectrum” (RES) within domesticated plants. Furthermore, little is known regarding if an intraspecific RES changes through plant ontogeny, and how trophic interactions – namely root nodulation – relate to above- or belowground trait spectra. Methods We evaluated covariation among 12 root, nodule, leaf, and stem traits in 134 plants of a single genotype of soy (Glycine max). Variation in these traits was assessed across five managed environmental conditions, and three plant ontogenetic stages. Results Root traits covaried along an intraspecific RES that represents a trade-off between resource acquisition and resource conservation. Variation along the RES was closely coordinated with hydraulic traits, but was orthogonal to nodule and leaf economics traits. Trait relationships varied strongly across managed environmental conditions and plant developmental stages. Conclusions Our results indicate the presence of an intraspecific RES in soy that is independent of root nodule investment. Patterns of phenotypic variation in below and aboveground soy traits demonstrate multivariate trait syndromes vary across environmental gradients and are dynamic through plant ontogeny.
... This might be due to the composition and nutritional adequacy of these plants in relation to hosts from other botanical families (Pashley, 1986(Pashley, , 1988Barros et al., 2010) with the consequence that, ultimately, insect foraging is an exercise in acquiring the best blend and balance of suite nutrients, including amino acids, carbohydrates, sterols, phospholipids, fatty acids, vitamins, minerals, trace elements, and water (Behmer, 2009). In this regard, soybean leaves presented starch (carbohydrate) varying from 40 to over 120 mg dm −2 ; soluble carbohydrate from 30 to 50 mg dm −2 , protein from 70 to 110 mg dm −2 , and inorganic phosphate from 20 to 60 50 mg dm −2 (Mondal et al., 1978). Hall (1951) reported the biochemical composition of cotton leaves for carbohydrate and nitrogen contents (percentage of dry weight). ...
Article
Full-text available
We studied Spodoptera frugiperda development using different food sources in the laboratory and field. Newly hatched larvae were fed soybean, cotton, maize, wheat, and oat leaves. An artificial diet was used as the control. Duration of pre-pupal, pupal, and larva-adult period, pupal weight, sex ratio, survival, larva feeding preferences, oviposition preferences, and nutritional quality of different hosts were evaluated. Insects fed on wheat showed the shortest larva-adult period. The insects fed on cotton and soybean had longer larval development cycles and pupae of lower weight. Feeding preference was evident for third instar larvae and did not differ between wheat, oat, maize, and soybean, which were the preferred hosts. Moths oviposited to a greater extent on the upper canopy of wheat than that of other plants in both the no-choice and free-choice tests. Treatments influenced insect growth, food consumption, and digestion when nutritional variables were analyzed. Thus, grasses were better hosts for S. frugiperda development. Cotton was the least preferred food, followed by soybean. The present study can improve our understanding of S. frugiperda in these different crops and help in developing management strategies. Even though S. frugiperda is considered to be polyphagous, this pest is closely associated with grasses (maize, wheat, oat) and has lower potential as a soybean or cotton feeder. Howerver, S. frugiperda food intake regulation appears to be triggered by a complex of different mechanisms. Thus, S. frugiperda can also damage soybean and cotton and adapt to them in the absence of preferred hosts.
... Cytokinins are involved in many plant developmental processes including cell division, apical dominance, seed germination, and source/sink relationships and have also been shown to delay senescence (Hutchison & Kieber 2002). The overrepresentation of starch biosynthesis in the leaves of sterile plants correlates with previous sink removal studies that found increased -Brandner & Egli 1987;Mondal et al. 1978;Schaffer et al. 1986). Similarly, we found that expression of genes encoding starch branching enzymes increased continuously in leaves of sink-limited plants. ...
... A decline in photosynthesis and the loss of leaf protein characterize the senescence of soybean leaves. The visual symptom of leaf yellowing is widely used as an index of plant and leaf senescence [31][32][33]. The maturation of soybean and abscission of leaves are a natural process. ...
Article
Full-text available
Soybean is considered one of the most valuable crops in the United States of America. Helicoverpa zea (Boddie) is among several insect pests which are associated with soybean, damaging leaves when infestations occur during the vegetative stages, and flowers and pods during the reproductive stages, which can directly impact yield. Artificial fruit removal is a method used to understand insect damage and to adjust action levels for control. The objective of this work was to evaluate the impact of five levels of fruit removal (0%, 25%, 50%, 75% and 100%) at four stages (R2, R3, R4 and R5) on maturity and yield of soybean. These methods were used to simulate H. zea damage under controlled conditions in non-irrigated environments, during 2016 and 2017. There was a significant interaction between fruit removal timing and fruit removal level for the percentage of non-senesced main stems and abscised leaves. For soybean yield, there was no significant interaction between fruit removal timing and fruit removal level. Plots that received fruit removal treatments at R5 had significantly lower soybean yields compared to plots that received damage at other growth stages and the nontreated control. Plots with 100% fruit removal had significantly lower yields compared to plots that received any of the other fruit removal treatments. These data demonstrate that indeterminate midmaturity group IV soybeans that are commonly grown in the midsouthern region of the United States may be able to compensate for even severe levels of fruit loss early during the reproductive portion of the growing season if favorable growing conditions occur.
... In particular, photosynthesis (Basis 2) is reportedly affected significantly by environmental factors, such as light, temperature, and states of nutrient sinks such as fruits and grains. Accordingly, (1) photosynthetic activity is inhibited under sub-optimal growth conditions involving non-optimal light or temperature [58][59][60] ; and (2) photosynthetic activity is reduced when nutrient sinks are removed and the need for C assimilation decreases [61][62][63][64][65] . Similarly, the bases representing phenylpropanoid biosynthesis (Basis 1) and senescence-associated hormone responses (Basis 4) are reportedly sensitive to various environmental factors: (1) flavonoids can be induced by UV-B 66 ; and (2) amounts of senescence-associated hormones, such as abscisic acid, ethylene, and jasmonic acid, can be varied in response to various types of stimuli 67 . ...
Article
Full-text available
Flag leaves (FL) and second leaves (SL) in rice show differential aging patterns during monocarpic senescence. Coordination of aging programs between FL and SL is important for grain yield and quality. However, the molecular bases for differential aging programs between FL and SL have not been systematically explored in rice. Here, we performed mRNA-sequencing of FL and SL at six time points during grain-filling and identified four molecular bases for differential aging programs between FL and SL: phenylpropanoid biosynthesis, photosynthesis, amino acid (AA) transport, and hormone response. Of them, photosynthesis (carbon assimilation) and AA transport (nitrogen remobilization) predominantly occurred in FL and SL, respectively, during grain-filling. Unlike other molecular bases, AA transport showed consistent differential expression patterns between FL and SL in independent samples. Moreover, long-distance AA transporters showed invariant differential expression patterns between FL and SL after panicle removal, which was consistent to invariant differential nitrogen contents between FL and SL after panicle removal. Therefore, our results suggest that the supplies of carbon and nitrogen to seeds is functionally segregated between FL and SL and that long-distance AA transport is an invariant core program for high nitrogen remobilization in SL.
... figure 1. These have agreed with research that during early stage of development defoliation can influence growth and survival of the plants 15 . It's also in line with a report that the higher the number of leaves produces the higher the photosynthesis rate, thereby increasing the energy substrate, hence the overall productivity of the plant 16&17 . ...
Article
Full-text available
Cowpea which is value mainly depends on high Protein contain and resistance to droughts, its production worldwide faces a lot of challenges among which is defoliation caused mainly by farm animal and some insects. The present study is aimed at studying the effect of defoliation on the growth and yield of some cowpea varieties. The research was conducted in IITA research station located at Latitude 12 0 , 03 1 N and Longitude 08 0 32 1 E, from May to November 2009. Two varieties of cowpea were used and arranged in randomize block design (RBD) with three replications. The treatment imposed are 0%, 50%defoliation at vegetative stage, 50% defoliation at flowering stage, 75% at vegetative stage, and 75% at flowering stage. The data taken during the study were plant height, date of first flowering (DFF), date of 50% flowering (DTF), date of harvest, pod number (PN), pod weight (PW), seed number (SN), and seed weight (SW). The result revealed that defoliation at 75% vegetative growth stage cause considerable reduction in yield components, while 50% vegetative reproductive growth stage revealed insignificant reduction in yield of cowpea which in conclusion, the experiment revealed that 75% defoliation at vegetative stage significantly reduce the yield of cowpea.
... Although the CO 2 assimilation rate is genetically determined, exogenous factors, such as water deficit, exerts substantial control over it (Liu et al. 2004a). Endogenous factors can also reduce the CO 2 assimilation rate by a negative feedback effect on photosynthesis due to high leaf carbohydrate content (Mondal et al. 1978;Ribeiro et al. 2012). In soybean, the pods and seeds are the major sink tissues and their size and number per plant determine grain yield (Declaux et al. 2000;Egli and Bruening, 2004). ...
Article
Full-text available
Water deficit is a major factor limiting crop yield in rainfed areas. We hypothesized that under water deficit the decrease of photosynthetic production stimulates: carbohydrate remobilization from leaves, stems and roots to reproductive organs; and decreasing flowering intensity and pod development. The present work aims to study the effect of water deficit during bloom and grain pod-filling stages in two indeterminate soybean cultivar, Vtop and Nidera. The following physiological parameters were evaluated by means of daily CO2 assimilation rate (Ai), dynamic of carbohydrates in tissues, plant growth, grain yield and yield components. The study was conducted in a greenhouse with plants sown in tanks of 0.5 m³. Regardless of the phenological phase, water deficit reduced Ai, plant growth and number of pods and seeds per plant. The fact that grain yield was less affected by water deficit at bloom than at grain pod-filling stage was attributed to larger seeds found at bloom. In both treatments, a sharp reduction on carbohydrate content was found in leaves, stem and roots at the beginning of pod formation. The high amounts of carbohydrates remobilized for seed growth, along with the high values of Ai observed in well-watered plants, indicate that grain yield of soybeans is source rather than sink limited. On the other hand, in water deficit treatments, a new stimulus for carbohydrate storage was found in the leaves and stem at the beginning of grain maturity, suggesting that grain yield was limited by sink capacity.
... In red clover, similar uneven starch distribution patterns were observed in plants measured at EN [13]. This observation is consistent with previous reports on the influence of leaf maturity on starch content in other species [42,43]. Because there is a high repeatability in NSC content at ED when total leaf biomass is analyzed, this uneven distribution of starch across the plant does not appear to influence the variation in whole-plant NSC content. ...
Article
Full-text available
White clover (Trifolium repens L.) is one of the most important legumes for fodder production in temperate climates, particularly in intensive pasture systems. Like many other forage legumes, it lacks the energy content to maximize productivity of modern ruminant livestock breeds. White clover produces water-soluble carbohydrates and starch in its leaves as a diurnal product of photosynthesis. However, little is known about the genetically encoded variability of diel changes in carbohydrate content. We assessed the amount of glucose, fructose, sucrose, and starch in the leaves of 185 plants of a genetically diverse white clover population. Water-soluble carbohydrates only provided on average 10.6% of dry weight (DW) of the total analyzed non-structural carbohydrate (NSC) content at the end of the day (ED), while starch supplied 89.4% of the NSC content. The top 5% of individuals accumulated over 25% of their DW as starch at ED. The leaf starch content at ED showed up to a threefold difference between genotypes, with a repeatability value of 0.95. Our experiments illustrate both the physical potential of white clover to serve as a competitive energy source to meet the demand of modern ruminant livestock production and the genetic potential to improve this trait by breeding.
... Depodding, which has often been used in previous studies, promotes the delayed senescence of leaves and stems (Crafts-Brandner et al., 1984;Crafts-Brandner & Egli, 1987;Egli & Bruening, 2006;Htwe et al., 2011;Leopold et al., 1959;Mondal et al., 1978;Wittenbach, 1982) and has been thought to imply that GSD is related to source-sink balance, that is, a relative increase in source levels resulting from sink limitation (Egli & Bruening, 2006;Wittenbach, 1983aWittenbach, , 1983b. However, depodding is a time-and labor-consuming method and is difficult to do, especially in a field experiment. ...
Article
Full-text available
Green stem disorder (GSD) in soybean (Glycine max (L.) Merrill) negatively affects harvest efficiency and seed appearances. Breeding GSD-insensitive cultivars is expected to be an effective countermeasure to GSD. However, it is difficult to stably detect cultivar differences in GSD under conventional field conditions because the occurrences of GSD largely vary by location and year. The thinning effect, which had been reported to promote GSD, may help accurate phenotyping for occurrences of GSD in breeding. To verify this possibility, the thinning treatment was applied to four cultivars, the GSD severity values of which were evaluated in an independent study by another group. As a result, the cultivar differences in GSD severity were generally comparable between the present and previous studies. However, the difference was more evident, with the thinning treatment exhibiting the GSD score of 2.8 of ‘Hatsusayaka’ compared with the GSD score of 3.6 of ‘Sachiyutaka’, while the scores of those cultivars were similar without the thinning treatment. A positive correlation between GSD severity and N concentration in the main stem could be seen but the increasing rate of GSD score with the N concentration in the main stem differed between cultivars. Thus, although more cultivars need to be tested to prove, the thinning treatment could be useful as a phenotyping technique in the breeding of GSD-insensitive cultivars.
Article
The hypothesis that leaves of soybean plants need to senesce in order to provide nitrogen for seed development has been used to explain the mechanism by which late‐season foliar applications of N P K and S solutions sometimes increase seed yields. A review of results of recent field and laboratory trials suggests that late‐season foliar fertilization does not inhibit leaf senescence and that such senescence is in any case not a primary factor in limiting seed yields.
Article
Relatively little change was observed in the partitioning of photosynthetically fixed carbon between sucrose and starch during senescence of vegetative leaves of wheat (Triticum aestivum L. cv. Roy). The maximum activities of sucrose phosphate synthase and cytoplasmic fructose-1, 6-bisphosphatase in leaf extracts approximated photosynthetic sucrose formation in leaf segments and the three parameters declined together with age. Changes in activities of sucrose synthase and uridine-5'-diphosphatase, and in leaf phosphate content did not parallel changes in sucrose formation with age. Chloroplast fructose-1, 6-bisphosphatase activity, activated in vivo with light and in vitro with dithiothreitol, declined continually throughout senescence of the second vegetative leaf. The ability of light to activate chloroplast fructose-1, 6-bisphosphatase did not, however, appear to change with age. Ribulose-l, 5-bisphosphate carboxylase activity also declined continually with age, but in vivo-activated ribulose-l, 5-bisphosphate carboxylase was a minimum of three fold greater than needed to account for photosynthetic activity. The percentage of ribulose-l, 5-bisphosphate carboxylase activated in vivo was essentially constant during senescence. In general, activities of soluble chloroplast enzymes declined continually from the point of full leaf expansion throughout senescence, whereas the activities of cytoplasmic enzymes that were studied remained relatively constant until the latter stages of senescence.
Article
: A large proportion of soybean flowers abort during development. Pod set is significantly affected by the availability of assimilate and cytokinin in the flowers, but their synergistic effects on pod set remain unclear. The objective of this study was to examine whether pod set at specific nodes of a plant is enhanced by increasing the source-sink ratio and applying cytokinin to the nodes. The source-sink ratio was manipulated by removing floral buds excluding the specific nodes. As the ratio increased, the number of pods per node of control plants increased curvilinearly, reaching a plateau at high source/sink ratios. By contrast, in the cytokinin-applied plants, the number of pods per node increased without the plateau with increasing source/sink ratio, either by increasing the number of flowers or by increasing the pod-set percentage depending on the year. The results indicated that cytokinin plays a promotive role in increasing pod number in the plants with high levels of assimilate availability.
Article
The partial shading effect on the photosynthetic apparatus of the sunflower (Helianthus annuus L.) was examined by monitoring oxygen evolution, maximum quantum yield of PSII photochemistry in dark-adapted leaves (Fv/Fm), the chlorophyll (Chl) concentrations and the Rubisco contents, and leaf mass per area (LMA) at the leaf level and by determining the concentrations of cytochrome (Cyt) f and the reaction centres of photosystem (PS) I and PSII at the thylakoid level. In this experiment, partial shading was defined as the shading of 2nd leaves with shade cloths, and the whole treatment was defined as the covering of the whole individuals with shade cloths. In the leaf level responses, oxygen evolution, LMA, Chl concentrations and Rubisco contents decreased in all shade treatments administered for six days. Fv/Fm remained constant irrespective of the shade treatments. On the other hand, in the thylakoid-level responses, the concentrations of the thylakoid components per unit Chl and the stoichiometry of the two photosystems showed no statistical difference among the shade treatments. The data obtained from the present study indicate that the partial shading affected the leaf-level responses rather than the thylakoid-level responses. The light received at the lower leaves might serve as a factor in the regulation of the leaf properties of the upper leaves due to the whole plant photosynthesis, while this factor did not have an effect at the thylakoid level.
Article
The variations in inorganic phosphate (Pi) and carbohydrates were followed during senescence of wheat flag leaves grown in experimental fields under Mediterranean climate. Different patterns were observed depending on the stage of senescence of the leaves and grain development. The relationships between Pi levels and carbohydrate also changed during the process. During the first stages of senescence, daily variations in Pi were related with changes in the starch/sucrose ratio Pi content also seemed to be related to the loss of RuBP-Carboxylase activity. At later stages of the process, the accumulation of carbohydrates in the leaves coincided with a rapid loss of RuBP-Case activity and photosynthesis but not with a substantial loss of inorganic phosphate of the leaves.
Article
Translocation of 14C-labeled assimilates from soybean leaves to the pods was examined during pod maturation and leaf senescence. The degree of seed development was expressed as stages of radicle yellowing which was related to other changes in the seeds as well as yellowing of the carpels, the leaf veins and the leaf intervenal tissue. To study translocation, a whole leaf was labeled with 14C−CO2 (30 min) or 14C-sucrose was applied to a small area on the upper surface of a leaf. Vein yellowing does not affect export of 14C-photosynthate from the leaf, and hilum browning does not alter import of photosynthate by the pods. The seeds can import 14C from the neighboring leaf even when carpels and seeds are completely yellow. The leaves can export 14C to the pods after they have lost their photosynthetic capacity, apparently until they abscise.
Article
A problem often encountered when assaying mesophyll cell isolates prepared from mature soybean leaves, was that of poor reproducibility in rates of net 14CO2 photoassimilation and NO2− photoreduction. It was known that soybean source leaves repeatedly displayed their most active net CO2 photoassimilation in the period from attainment of maximal leaf area to approximately two to five days subsequent to that point. Advantage was taken of the fact that when soybean leaflets of each leaf reach their maximal area they also have reached their maximal leaf length from base to tip. This facilitates a more rapid determination of the point in time in which leaflet areas had reached Amax. Soybean plants (Glycine max cv. Williams) were propagated in the growth chamber with a 12 h light-12 h dark cycle, 25δC, 65% RH, and 700 microeinsteins per meter squared per second. At 24 d post-emergence, the third leaf (numbered acropetally from the unifoliates) of each plant had just attained maximum leaflet areas (≈110 cm2) and lengths (≈13 cm). For this study, leaf mesophyll cells were enzymatically isolated, using commercially prepared pectinase, from leaflet sets of leaves selected from each of the second, third, and fourth leaf positions. Maximal rates of net 14CO2 photoassimilation (with 5 mM HCO3−) for the second, third and fourth leaf (leaflet) isolates were, respectively, 27.0, 57.0, and 41.7 μmol 14CO2 assimilated per milligram chlorophyll per hour; simultaneously maximal rates of NO inf2sup−photoreduction (1 mM NO inf2sup−) were, respectively, 4.4, 8.1, and 0.0 μmol NO inf2sup−reduced per milligram chlorophyll per hour. These studies made it clear that in order repeatedly to attain reproducible maximal rates of leaf cell isolate net 14CO2 photoassimilation and NO inf2sup−photoreduction, it always was necessary to select the newest, fully expanded leaves (e.g. leaf number 3) for cell isolation. Leaves from several plants only were pooled if they were excised from identically the same node on each of the plants.
Article
In some soybean (Glycine max (L.) Merr.) cultivars, fruit removal does not delay the apparent loss of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco, EC 4.1.1.39) activity and abundance or the decline in photosynthesis. Analysis of leaf extracts from defruited plants indicated a time-dependent increase in both Rubisco activity and abundance in a 30000 · g pellet fraction in cultivars which had been reported to lose all Rubisco protein from the supernatant fraction. Attempts to solubilize the pelleted Rubisco by increasing the buffer volume/tissue ratio or by adding alkylphenoxypolyethoxyethanol (Triton X-100), ethylenediaminetetraacetic acid (EDTA), or NaCl were unsuccessful. However, treatment of the pellets with denaturants such as 8 M urea or 5% (w/v) sodium dodecyl sulfate (SDS) did release Rubisco from the pellet. Redistribution of protein to the pellet fraction appeared to be specific for Rubisco since the amount of ribulose-5-phosphate kinase (EC 2.7.1.19) found in the pellet fraction of leaf extracts of control and defruited plants was small and constant over time. The loss of soluble Rubisco, and the concomitant increase in insoluble Rubisco, in response to fruit removal varied with genotype and was reproducible in both field and greenhouse environments. In addition, the effect was influenced by node position and light; lower and-or shaded leaves exhibited less Rubisco in the pellet fraction than leaves from the top of the plant that was fully exposed to sunlight. When isolated by sucrose-density-gradient centrifugation, the insoluble Rubisco was found to co-purify with a 30-kDa (kilodalton) polypeptide. These results indicate that alteration of the source/sink ratio by removing fruits results in the formation of an insoluble form of Rubisco in leaf extracts of soybean. Whether or not Rubisco exists as an insoluble complex with the 30-kDa polypeptide in intact leaves of defruited plants remains to be determined.
Article
Full-text available
Green stem disorder (GSD) of soybean is characterized by delayed leaf and stem maturation despite normal pod maturation. Previous studies have suggested that GSD occurrence is promoted by a high source–sink ratio, which is produced by thinning or shade removal at the R5 growth stage (the beginning of seed filling). Here the effects of different times and durations of shade removal after the R5 stage on GSD severity were analyzed. First, shade removal for more than 28 days after R5 increased GSD severity by more than 0.4 point in GSD score. Thinning treatment at R5 increased specific leaf weight by 23%, suppressed stem dry weight reduction, and upregulated 19 genes including those encoding vegetative storage proteins at R5 + 28d, indicating excess source ability relative to sink size. On the contrary, shade removal for 14 days after R5 decreased GSD severity by 0.5 point in GSD score. In this treatment, seed size was smaller, while seed number was significantly larger than control, suggesting that shortage of source ability relative to sink size. These results implied that soybean plants regulate GSD occurrences either positively or negatively according to a source-sink ratio during the R5 to R5 + 28d growth stages.
Article
Changes in the level of metabolites in leaves and pods were examined with respect to the seed chemical composition in black soybean. There was no further increase in pod length after 42 days after flowering (DAF). Pod weight, however, persistently increase until 73 DAF, thereafter the weight was slightly lowered. The seed storage protein, however, increased drastically as the increasing rate of pod weight was lessened at 61 DAF. The accumulation of seed storage proteins was occurred conspicuously as the increasing rate of pod weight was slowed down. The chlorophyll content both in leaves and pods was drastically decreased after 50 DAF. The beginning of drastic reduction in chlorophyll content was occurred concomitantly with the reduction of soluble protein content in leaves. The sugar content in leaves showed similar tendency with chlorophyll and soluble protein content. The starch level in leaves, however, showed different changing pattern during seed development. The starch content in leaves was increased persistently until 66 DAF, thereafter the content was decreased drastically to about of maximal value at 66 DAF. Total phenolics content in leaves and the anthocyanins content in seeds were stable without noticeable increase until 66 DAF. The contents were increased dramatically after 66 DAF showing the synchronized pattern with the decrease in starch level in leaves. The levels of the selected metabolites in leaf and seed suggested that the accumulation of chemical components of black soybean seed is launched actively at 66 DAF. The profile of storage proteins was nearly completed at 61 DAF because there was no large difference in densitometric intensity among protein subunits after 61 DAF. In soybean, chemical maturation of seed begins around 61 to 66 DAF at which most metabolites in vegetative parts are decreased and remobilized into maturing seeds.
Article
Tomato fruit yield per area in Japan is 88% lower than that in The Netherlands, because higher-yielding tomato cultivars are bred and cultivated in The Netherlands. In this study, we investigated differences between the Japanese common cultivar 'Reiyou' and the Dutch high-yielding cultivar 'Levanzo' in fruit yield and components contributing to an increase in fruit yield using the low-node-order pinching and high-density plant training system used in Japan. Fresh and dry fruit yield of 'Levanzo' were significantly higher than those of 'Reiyou'. Estimated leaf blade area of the whole plant and solar radiation on individual leaves were higher in the 'Levanzo' canopy than in that of 'Reiyou'. Although transpiration rate and stomatal conductance were similar in the two cultivars during the latter half of the fruit development period, the photosynthetic rate in 'Levanzo' was higher than that in 'Reiyou' during the fruit development period. The difference in photosynthetic rate was because chlorophyll a and b content had not decreased in 'Levanzo' compared with that in 'Reiyou' at 50 days after flowering, corresponding to the latter half of the fruit development period. Transcriptional levels of LeSUT1, which determines sucrose loading activity in source leaves, did not differ between the two cultivars. The higher tomato fruit yield of 'Levanzo' compared with that of 'Reiyou' was caused by a higher photosynthetic rate, increased solar radiation on individual leaves, and the large sink size due to numerous fruits, but not by sucrose loading activity.
Article
Workers are beginning to study the in vivo enzymatic activity of several leaf proteins. The relationship between in vivo activity and enzyme concentration suggests that in vivo regulation may often be more important than the concentra­ tion of the protein catalyst. In addition to allosteric effectors, the sources of energy that drive certain enzymatic reactions are important regulators. The activity of some cytoplasmic enzymes may be driven by glycolysis and by systems that shuttle ATP and reducing power from the chloroplast or mitochondria to the cytoplasm. For example, several biochemical pathways are integrated in the regulation of nitrate reductase (NR) activity. Since photosynthetic CO2 fixation supports both the synthesis and activity of nitrate reductase, the turnover of RuBPCase can strongly affect nitrate reductase (NR). The leaf storage proteins are extremely important in the maturation, repro­ duction, and final seed yields of plants. Nitrogen is a main factor that limits photosynthetic capacity and seed yield as the plant matures. Final seed yields often depend on the proteolysis of stored leaf N and its translocation to the seed (DALLING et al. 1975, HAGEMAN and LAMBERT 1981). Proteolysis of storage protein can be induced by environmental factors such as limitations in N supply, water, light, and temperature.
Chapter
To examine the effects of different pressures by livestock grazing on plant production and species diversity, we conducted mowing experiments using pasture plants at different heights and intervals in an exclosure in a flat valley bottom with high production and on an upper slope with low production in a Mongolian pasture. We transported the trimmings of pasture plants to the laboratory and weighed them. Mowing of pasture plants at different intervals revealed that the optimal annual production occurred when mowing was conducted at intermediate intervals of 30 days. Monthly mowing at heights of 3 and 5 cm revealed higher annual production for the 5-cm height in the flat valley bottom and for the 3-cm height on the upper slope. In another series of experiments, mowing at heights of 0 and 3 cm and at different intervals for 4 years revealed higher annual production and species diversity following mowing at 3 cm in the fourth year. Our results suggest that the annual production and species diversity of pasture plants is optimized by intermediate pressure from livestock grazing.
Article
Efforts to determine the mechanistic relationships between fruit and canopy development are complicated by difficulties in designing nondestructive treatments that modify plant-sink development. Pod growth was physically restricted by placing plastic straws, referred teas plastic pod-restriction devices, over 0, 50, or 100% of the soybean (Glycine mar L. Merr.) pods in greenhouse experiments. The objective was to determine how decreases in pod growth influenced whole-plant growth and development. Both the rate and final accumulation of seed dry matter were decreased by restricting pod growth. Conversely, restricting pod growth increased seed number due to increased production and decreased abscission of fruits. Plant dry matter and N accumulations during the linear seed-fill period were not affected by restricting pod growth. This resulted from proportional increases in partitioning of assimilates into stems and leaves. Thus, decreases in reproductive growth apparently did not cause feedback inhibition of photosynthesis. Although leaf abscission was delayed by restricting pod growth, dry matter and N accmulation late in development were affected only slightly. In general, restricting pod growth influenced plant develop ment and assimilate allocation in a similar manner as physical removal of fruits. The inverse relationship between the rate of dry matter accumulation in seed and pod and seed number per plant indicated that assimilate availability limited seed number. The delay in leaf yellowing and abscission induced by physically restricting pod growth suggested that the completion of monocarpic senescence was directly affected by changes in the rate of seed dry matter accumulation per plant.
Chapter
Ribulose 1, 5-bisphosphate carboxylase (RuBPCase) has a central role in the C and N economy of many crop plants. In C3 plants, RuBPCase catalyzes the primary rate-limiting step in CO2 fixation (Jensen and Bahr, 1977; Bahr and Steffens, this volume). RuBPCase also functions as a storage protein and is rapidly degraded during leaf senescence (Friedrich and Huffaker, 1980; Wittenbach et al., 1980). The catalytic properties of RuBPCase and other Calvin-cycle enzymes have been thoroughly reviewed (Jensen and Bahr, 1977; Bahr and Steffens, this volume; Buchanan, this volume). Likewise, the regulation of RuBPCase degradation has been discussed (Huffaker and Miller, 1978; Miller and Huffaker, this volume; Thomas and Stoddart, 1980). Therefore, this article will focus mainly on the role of RuBPCase as a storage protein and on the relationship between RuBPCase concentration and photosynthesis.
Article
In order to understand the regulation of source-sink relationship on leaf senescence in maize, we investigated the effect of pollination prevention on leaf senescence, post-silking dry matter and nitrogen accumulation and remobilization in different vegetative organs in one landrace and ten representative maize hybrids released between 1973 and 2000 in China. When pollination was prevented by covering silk with paper bags at silking stage, leaf senescence of Nongda 60, Yedan 13, Shendan 7 and Zhengdan 958 was delayed as shown by the remaining green leaf area per plant at maturity. However, pollination-prevention did not have obvious effect on the leaf senescence of Baimaya, Danyu 6, Yedan 2 and Xianyu 335. By contrast, pollination-prevention accelerated the leaf senescence of maize hybrids Zhongdan 2, Danyu13 and Yedan 4. It was found that leaf senescence of the late-released (since 1985) Chinese hybrids tended to be delayed by pollination-prevention, except XY335. From silking to physiological maturity, nitrogen content increased in the stem (plus the sheath, cob, husk, and tassel) and root of the non-pollinated plants. However, there was still a net reduction in leaf nitrogen content. We also found that pollination-prevention reduced leaf nitrogen remobilization efficiency, with genotypic difference and variation between the two years of testing. The results suggested that the response of leaf senescence to pollination-prevention is at least partially due to the change of leaf nitrogen remobilization efficiency. Leaf senescence tended to be delayed if leaf nitrogen remobilization efficiency is highly reduced by pollination-prevention.
Article
The research was conducted in experimental garden of Faculty of Agriculture Unwim which has a place to stay 850 mdpl. This study aims to determine the effective timing of male pruning to increase yield components and sweet corn yield. The environmental plan used is a collection of groups consisting of: A = Without pruning B = Pruning 7 days after pollination C = Pruning 14 days after pollinationD = Pruning 21 days after pollination. The result of the research showed that the male flower pruning after pollination of the effect on corn yield and yield components such as Weight, Length and Diameter of Tonggol both without and with kelobot. Sweet corn plants that are not exposed to male flower pruning have the same result and yield components as the plants that are trimmed by their male flowers
Article
Since natural materials, such as phytochemicals in plants, are increasingly being used for foods and skincare due to their beneficial functions, it is important for developing the cultivation practices to increase the contents of phytochemicals. We here explored metabolite perturbations in the leaves of soybean plants when their pods were removed during growth through ¹H NMR-based metabolomics approach. There were obvious metabolic differences in the leaves between normal and pod-removed soybean plants. High amounts of primary metabolites in pod-removed soybean leaves, including amino acids, sugars, and fatty acids, reflected a delay of leaf senescence caused by pod removal. In particular, amounts of isoflavones, coumestrol, and apigenin derivatives in pod-removed soybean leaves were substantially increased. These were considered as distinct metabolic influences of pod removal in soybean plants. These results indicate that pod removal of soybean plants can induce significant perturbations of various metabolites in their soybean leaves, providing useful information to improve the quality of soybean leaves by increasing amounts of bioactive components.
Article
Full-text available
An investigation has been made of the changes in the major phosphorus containing substances in Avena sativa during the first 8 days of dark germination. The endosperm, roots, and shoots were analyzed separately for acid soluble-P, phytic acid-P, inorganic-P, lipid-P, nucleic acid-P, and protein-P. Phytic acid-P comprised 53% of the total seed phosphate, while the sum of lipid-P, nucleic acid-P and protein-P comprised 27% of the seed phosphate. All these reserve phosphate materials were mobilized and transferred to the developing axis. The phosphate from phytic acid appeared almost entirely as inorganic-P in the roots and shoots. A close stoichiometry existed between the rate of loss of nucleic acid-P from the endosperm and its rate of appearance in the roots and shoots. Thus no net synthesis of nucleic acid occurred during the 8-day period examined. The rate of synthesis of lipid-P in the roots and shoots exceeded its rate of disappearance from the endosperm during the first 4 days of germination. Protein-P increased in the roots and shoots during germination, but at a rate less than its rate of disappearance from the endosperm. The results provide a relatively complete description of the over-all aspects of phosphorus metabolism associated with germination of oats.
Article
Both environmental factors and manipulative treatments (such as fruit excision or stem cincturing) were found to alter gaseous diffusion resistances in grape vine foliage. These responses have been analysed in terms of the hormonal physiology of Vitis vinifera L. leaf tissue. Environmental factors such as moisture stress or photoperiod alterations which contributed towards an increase in stomatal resistance (rs) were correlated with increased levels of endogenous abscisic acid (ABA) and phaseic acid (PA) in mature foliage. Conversely, treatments which elicited a decrease in rs were associated with lower levels of both ABA and PA. For example, rs had increased from 1.41 to 7.14 s cm-1 7 days after fruit removal and stem cincturing, while ABA and PA levels rose by 50 and 370 % respectively. This increase in endogenous ABA was not a consequence of decreased leaf water potential; moisture status was actually improved after treatment. It is proposed that changes in endogenous levels of ABA, and possibly PA, constitute a mechanism for regulating gas exchange in these perennial plants.
Article
Two weeks after anthesis, when the grain is filling rapidly, the rate of photosynthesis by flag leaves of wheat cv. Gabo was between 20 and 30 mg CO2 dm-2 leaf surface hour-1 under the conditions used. About 45% of flag-leaf assimilates were translocated to the ear, and only about 12% to the roots and young shoots. On removing the ear, net photosynthesis by the flag leaves was reduced by about 50% within 3–15 hours, and there was a marked reduction in the outflow of 14C-labelled assimilates from the flag leaves. Subsequent darkening of all other leaves on plants without ears led to recovery of flag-leaf photosynthesis, as measured by gas analysis and 14CO2 fixation, and to increased translocation of assimilates to the roots and young shoots. Minor changes in the rates of dark respiration accompanied these major, reversible changes in photosynthetic rate. After more than a week in continuous, high-intensity light, the rate of photosynthesis by flag leaves of intact plants had fallen considerably, but could be restored again by a period in darkness, or by inhibiting photosynthesis in the ears by spraying them with DCMU. The inhibition of ear photosynthesis increased translocation of labelled assimilates from the flag leaf to the ears, without affecting leaf sugar levels. The application of TIBA to the culm below the ear inhibited auxin movement throught the culm, but had no influence on flag-leaf photosynthesis. These results suggest that, at least in this system, photosynthesis by the flag leaf is regulated directly by the demand for assimilates from the flag leaf and not indirectly through action in the leaf of auxins produced by the “sink” organs.
Article
Kinetic properties of soybean net photosynthetic CO(2) fixation and of the carboxylase and oxygenase activities of purified soybean (Glycine max [L.] Merr.) ribulose 1, 5-diphosphate carboxylase (EC 4.1.1.39) were examined as functions of temperature, CO(2) concentration, and O(2) concentration. With leaves, O(2) inhibition of net photosynthetic CO(2) fixation increased when the ambient leaf temperature was increased. The increased inhibition of CO(2) fixation at higher temperatures was caused by a reduced affinity of the leaf for CO(2) and an increased affinity of the leaf for O(2). With purified ribulose 1,5-diphosphate carboxylase, O(2) inhibition of CO(2) incorporation and the ratio of oxygenase activity to carboxylase activity increased with increased temperature. The increased O(2) sensitivity of the enzyme at higher temperature was caused by a reduced affinity of the enzyme for CO(2) and a slightly increased affinity of the enzyme for O(2). The similarity of the effect of temperature on the affinity of intact leaves and of ribulose 1,5-diphosphate carboxylase for CO(2) and O(2) provides further evidence that the carboxylase regulates the O(2) response of photosynthetic CO(2) fixation in soybean leaves. Based on results reported here and in the literature, a scheme outlining the stoichiometry between CO(2) and O(2) fixation in vivo is proposed.Oxygen competitively inhibited carboxylase activity with respect to CO(2), and CO(2) competitively inhibited oxygenase activity with respect to O(2). Within the limits of experimental error, the Michaelis constant (CO(2)) in the carboxylase reaction was identical with the inhibition constant (CO(2)) in the oxygenase reaction, and the Michaelis constant (O(2)) in the oxygenase reaction was identical with the inhibition constant (O(2)) in the carboxylase reaction. The Michaelis constant, (ribulose 1,5-diphosphate) was the same in both the carboxylase and oxygenase reactions. This equality of kinetic constants is consistent with the notion that the same enzyme catalyzes both reactions.
Article
The movement of metabolites and nutrients towards developing seeds, and their accumulation there, appears to play an important role in the regulation of senescence of the shoot in annual plants. The possibility that the directed-transport of nutrients towards developing fruits is regulated by growth hormones has been studied in French bean (Phaseolus vulgaris). Application of 3-indolyl acetic acid (IAA), in lanolin, to peduncles from which the fruits had been removed, resulted in significantly greater accumulation of 32P (applied to the lower part of the stem) in the region of hormone application than in peduncles treated with lanolin only. When gibberellic acid (GA) or kinetin were applied alone to defruited peduncles they had no significant effect on the accumulation of 32P at the point of application of hormone, but when either was applied with IAA they greatly enhanced the effect of the latter on movement of 14C-labelled photosynthates from the leaves to the peduncles. It is suggested that hormone-directed transport may play an important role in directing the movement of nutrients towards developing seeds, which are rich sources of endogenous hormones.
Article
Net carbon dioxide uptake by a photosynthesizing primary leaf of bean plants, Phaseolus vulgaris cv. Black Valentine, was measured during treatments designed to alter export from the leaf. Removal of shoot apices lessened sink demand while removal of all source leaves except the one being observed increased sink demand. Export from the leaf under study was lessened by chilling the primary leaf petiole and node to 2 °C. No adjustments in the rate of net photosynthesis were observed during the 33-h period after any of the treatments.The results of this study are in general agreement with previous reports in the literature. After modification of sink demand or of export by experimental manipulation of plants, a period of 2 or 3 days is usually required for adjustment of net photosynthesis rate. Rapid changes in net photosynthesis rate are generally the result of concomitant changes in morphology or metabolism during the course of plant development. The results of this work, and of others in the literature, i...
Article
A colorimetric method using anthrone is described for the estimation of starch and soluble sugars in cereals, cereal by-products, and mixed poultry rations. The method is rapid and requires no elaborate apparatus. An internal glucose standard is used. Results for the starch content of these materials show a standard deviation of 2–2% of the mean value.
Article
Simple sugars, oligosaccharides, polysaccharides, and their derivatives, including the methyl ethers with free or potentially free reducing groups, give an orange-yellow color when treated with phenol and concentrated sulfuric acid. The reaction is sensitive and the color is stable. By use of this phenol-sulfuric acid reaction, a method has been developed to determine submicro amounts of sugars and related substances. In conjunction with paper partition chromatography the method is useful for the determination of the composition of polysaccharides and their methyl derivatives.
Article
Applications of hormones to fully expanded leaves of dwarf bean stimulate the activity of carboxydismutase. The increase in enzyme activity is not paralleled by synthesis of plastid ribosomal RNA nor is there a demonstrable enhancement of synthesis of fraction I protein. These results are interesting in relation to the activities of other photosynthetic enzymes.
Article
Since 1922 when Wu proposed the use of the Folin phenol reagent for the measurement of proteins (l), a number of modified analytical pro- cedures ut.ilizing this reagent have been reported for the determination of proteins in serum (2-G), in antigen-antibody precipitates (7-9), and in insulin (10). Although the reagent would seem to be recommended by its great sen- sitivity and the simplicity of procedure possible with its use, it has not found great favor for general biochemical purposes. In the belief that this reagent, nevertheless, has considerable merit for certain application, but that its peculiarities and limitations need to be understood for its fullest exploitation, it has been studied with regard t.o effects of variations in pH, time of reaction, and concentration of react- ants, permissible levels of reagents commonly used in handling proteins, and interfering subst.ances. Procedures are described for measuring pro- tein in solution or after precipitation wit,h acids or other agents, and for the determination of as little as 0.2 y of protein.
Article
Rates of net photosynthesis and translocation, CO(2) diffusive resistances, levels of carbohydrates, total protein, chlorophyll, and inorganic phosphate, and ribulose 1,5-diphosphate carboxylase activity were measured in soybean (Glycine max L. Merrill) leaves to ascertain the effect of altered assimilate demand. To increase assimilate demand, the pods, stems, and all but one leaf (the "source leaf") of potted plants were completely shaded for 6 or 8 days and the responses of the illuminated source leaf were monitored. Rate of net photosynthesis in the source leaf of the shaded plants was found to increase curvilinearly to a maximum on the 8th day. The source leaf of the control plants (no sink shading) maintained a constant photosynthetic rate during this period. Vapor-phase resistance to CO(2) diffusion did not vary with treatment, but mesophyll (liquid phase) resistance was significantly lower in the source leaf of the shaded plants.Starch concentration in the source leaf of shaded plants decreased more than 10-fold during the 8-day shading period. In this same period, sucrose concentration rose nearly 3-fold. Conversely, in the source leaf of the unshaded plants, starch concentration remained high (23% of leaf dry weight) and sucrose concentration remained very low (1.2%). When measured on the 8th day of treatment, translocation rate, ribulose 1,5-diphosphate carboxylase activity, and inorganic phosphate concentration were found to be significantly higher in the source leaf of the shaded plants than in the control source leaf.When shaded plants were again illuminated, all measured response trends in the source leaf were reversed. These data indicate that assimilate demand has a marked influence on source-leaf photosynthesis and carbohydrate formation and export.
Article
Net photosynthetic rate, CO(2) compensation concentration, and starch and soluble sugar concentrations were measured in soybean (Glycine max [L.] Merrill) leaves in an attempt to evaluate the effect of carbohydrate concentration on rate of CO(2) assimilation.Plants were grown in a controlled environment room at 23.5 C, 50% relative humidity, 16-hour photoperiod, and quantum flux (400-700 nm) of 510 mueinsteins/m(2).sec (30,090 lux) at plant level. On the 21st day after seeding, plants were subjected for 12.5 hours to one of three CO(2) concentrations (50, 300, or 2000 mul/l) in an attempt to alter leaf carbohydrate levels. Following the CO(2) treatment, gas exchange measurements were made at a CO(2) concentration of 300 mul/l on the lowermost trifoliolate leaf. Immediately after measurement, the leaf was removed and stored at -20 C until carbohydrate analyses were performed.Increasing the CO(2) concentration for 12.5 hours significantly increased leaf starch concentration but not soluble sugar concentration. There was a strong negative correlation between net photosynthetic rate and starch concentration. Net photosynthetic rate declined from approximately 38 to 22 mg CO(2)/dm(2) leaf area.hr as starch concentration increased from 0.5 to 3 mg/cm(2) leaf area. Carbohydrate concentrations had no effect on compensation concentration.The decrease in net photosynthetic rate as starch concentration increased resulted from an increase in mesophyll (liquid phase) CO(2) diffusion resistance. This suggests that starch accumulation may reduce net photosynthetic rate by impeding intracellular CO(2) transport.
Physiological phenomena at the time of flowering
  • Bachuyzen
BACHUYZEN HLS 1926 Physiological phenomena at the time of flowering. Proc Soc Exp Biol Med 24: 143-145
Effects of translocation and assimilate demand on photosynthesis HABESHAW D 1973 Translocation and control of photosynthesis in sugar beet Phosphorus metabolism of germinating oat seeds Effect of floral bud removal on performance of soybeans
  • Hall Jr Hodges
  • Dr
GEIGER DR 1976 Effects of translocation and assimilate demand on photosynthesis. Can J Bot 54: 2337-2345 8. HABESHAW D 1973 Translocation and control of photosynthesis in sugar beet. Planta 110: 213-226 9. HALL JR, TK HODGEs 1966 Phosphorus metabolism of germinating oat seeds. Plant Physiol 41:1459-1464 10. HICKS DR, JW PENDLETON 1969 Effect of floral bud removal on performance of soybeans. Crop Sci 9: 435-437
Effects of water stress on photosynthesis and transpiration of flag leaves and spikes of barley and wheat Effects of assimilate utilization on photosynthetic rate in wheat Regulation of soybean net photosynthetic CO2 fixation by the interaction of COa, O2 and ribulose 1,5-diphosphate carboxylase
  • Nm Rr Johnson
  • Frey
  • King Rw Moss
  • If Wardlaw
  • Laing Wa
  • Wl Ogren
JOHNsoN RR, NM FREY, DN Moss 1974 Effects of water stress on photosynthesis and transpiration of flag leaves and spikes of barley and wheat. Crop Sci 14: 728-731 12. KING RW, IF WARDLAW, LT EVANS 1967 Effects of assimilate utilization on photosynthetic rate in wheat. Planta 77: 261-276 13. LAING WA, WL OGREN, RH HAGEMAN 1974 Regulation of soybean net photosynthetic CO2 fixation by the interaction of COa, O2 and ribulose 1,5-diphosphate carboxylase. Plant Physiol 54: 678-685
Fruit effects on formation and distribution of photosynthetic assimilates
  • Lenz
LENZ F 1974 Fruit effects on formation and distribution of photosynthetic assimilates. XIX Intem Hort Cong Warsaw, pp 155-166
The significance of sucrose and starch contents of the leaves for the regulation of net photosynthetic rates
  • E Biller
CLAUSSEN W, E BILLER 1977 The significance of sucrose and starch contents of the leaves for the regulation of net photosynthetic rates. Z Pflanzenphysiol 81: 189-198
Effect of fruit removal on net assimilation and gaseous diffusive resistance of soybean leaves
  • Cn Williams
LENZ F, CN WILLIAMS 1973 Effect of fruit removal on net assimilation and gaseous diffusive resistance of soybean leaves. Angew Botanik 47: 47-63