Redistribution Of Assimilates Research Articles

Stem transcriptome screen for selection in wild and cultivated pitahaya (Selenicereus undatus): an epiphytic cactus with edible fruit.

Dragon fruit, pitahaya or pitaya are common names for the species in the Hylocereus group of Selenicereus that produce edible fruit. These Neotropical epiphytic cacti are considered promising underutilized crops and are currently cultivated around the world. The most important species, S. undatus, has been managed in the Maya domain for centuries and is the focus of this article. Transcriptome profiles from stems of wild and cultivated plants of this species were compared. We hypothesized that differences in transcriptomic signatures could be associated with genes related to drought stress. De novo transcriptome assembly and the analysis of differentially expressed genes (DEGs) allowed us to identify a total of 9,203 DEGs in the Hunucmá cultivar relative of wild Mozomboa plants. Of these, 4,883 represent up-regulated genes and 4,320, down-regulated genes. Additionally, 6,568 DEGs were identified from a comparison between the Umán cultivar and wild plants, revealing 3,286 up-regulated and 3,282 down-regulated genes. Approximately half of the DEGs are shared by the two cultivated plants. Differences between the two cultivars that were collected in the same region could be the result of differences in management. Metabolism was the most representative functional category in both cultivars. The up-regulated genes of both cultivars formed a network related to the hormone-mediated signaling pathway that includes cellular responses to auxin stimulus and to hormone stimulus. These cellular reactions have been documented in several cultivated plants in which drought-tolerant cultivars modify auxin transport and ethylene signaling, resulting in a better redistribution of assimilates.

Development of an irrigation regime for winter wheat to save water resources by avoiding irrigation at anthesis stage

AbstractLatest published information is limited on agronomic responses of winter wheat to irrigation quantity and the necessity of irrigation at the anthesis stage. This study was conducted to (1) evaluate winter wheat yield, water use, assimilate redistribution and economic benefit with respect to water input and (2) quantify relationship between water input and yield to develop a standard for withholding irrigation at anthesis. A 4‐year long field experiment was conducted to evaluate winter wheat water use, yield formation pathway and farmers' income under three irrigation regimes: rainfed, irrigation at sowing and jointing (SJ‐W) and irrigation at sowing, jointing and anthesis (SJA‐W). The yield formation pathway was correlated with the water‐induced variation in assimilate redistribution and accumulation. Throughout the experimental period, wheat yield was 19–38% lower in rainfed than that under other irrigation treatments. Moreover, SJ‐W treatment substantially increased biomass accumulation at anthesis, accelerated assimilate redistribution in vegetative organs and eventually resulted in a similar wheat yield to that of SJA‐W. Simultaneously, the SJ‐W treatment had lower irrigation water, reduced additional irrigation cost, suppressed yield loss and obtained a similar farmer's net income to the SJA‐W treatment. Water‐induced variations in yield were determined by irrigation, rainfall and soil water storage. SJ‐W plots receiving 204–331 mm water input (rainfall + irrigation) before anthesis and holding 549–587 mm soil water during anthesis stage achieved higher irrigation water use efficiency and yield relative to the rainfed and SJA‐W plots. In contrast, water input under rainfed plots exceeded 200 mm before anthesis, limiting yield substantially even when seasonal soil water consumption exceeded 160 mm. Developing a standard for withholding irrigation at the anthesis stage should incorporate 204–331 mm of water input (rainfall + irrigation) before anthesis and 549–587 mm soil water storage at anthesis, which could achieve a high wheat yield and save water resources.

Zoned potato varieties reaction on tuberization media in vitro

The conception of potato genotype specificity response to in vitro conditions forces us to optimize the cultivation conditions for each variety for microtuberization (MTB) method seed production. Zoned varieties, based on the similarity of field conditions requirements, could be cultivated on standardized media with the achievement of a sufficient average MTB efficiency. The morphometric parameters dynamics (7-62 days) of microplants from the collection of cultivars, widely cultivated in the Krasnoyarsk Territory, were studied on Murashige-Skoog media, containing MTB inductors: sucrose (80 g/L) (M0) and phytohormones in addition: kinetin (1 mg/L) (M1) or a combination of kinetin (2 mg/L), adenine, IAA (1.5 mg/L each) (M2). Hormone- free medium with 30 g/L sucrose was used as control. No inducing effect was detected of phytohormones on MTB frequency and process dynamic of investigated cultivars, except Red Scarlett, under sucrose concentration, had been used in the present study. The determining factor inducing MTB was a high level of sucrose (80 g/L). The phytohormones influence was manifested in the differences in the varietie`s growth parameters. Root systems of domestic cultivars Antonina, Charoit, Hozjajushka were completely developed by 28 days on all media. Close values of the shoot height and the internodes number on M0-M2 media during most of the cultivation period were detected. Meteor, Rosara, and especially Red Scarlett cultivars were distinguished by a decrease in growth parameters in the line of conditions Control> M0> M1> M2. Cultivars groups, marked in vitro, differ by the habitus of plants formed by cultivars under the field conditions. The first three cultivars are tall plants with large leaves, the second group consists of intermediate type plants. However, we can already speak, based on data on growth inhibition, about the advantage of media with phytohormones for cultivars with the same habit as the second group has. Such reaction may be indirect evidence of the redistribution of assimilates in favor of MTB.

Вплив екологічно безпечного регулятора росту на перерозподіл вуглеводів та азоту між органами рослин олійних культур

The aim of the research. Given that the existing data on the effect of growth inhibitors on the redistribution of assimilates in oil crops are not numerous and the controversial data on the effect of the anti-gibberellin drug chlormequat chloride on the content of carbohydrates and nitrogen the purpose of the experiment was to find out the influence of CCC on the redistribution of assimilates in oil crops.Methodology. Oil poppy and rapeseed plants of the Halytsky variety were treated during the budding period with a 0.5% solution of chlormequat chloride with a Mastertool hydraulic sprayer, while the plants of the control sample were treated with water. Experimental plots were laid in farms of the Podilskyi region in 2020-2021. The number of experimental plots of each of the experimental options is 5, the area is 5 m2. The content of total nitrogen was determined by the Kjeldahl method, sugars and starch content was measured using the iodometric method.
 The novelty of the research. The effect of a growth regulator on the redistribution of carbohydrates between plant organs during the growing season was for the first time investigated on the oil poppy culture. The accumulation of excessive carbohydrates in the leaves and roots of the experimental samples has a positive meaning due to the creation of a powerful reserve fund of assimilates. It is used for the formation and growth of the fruits of the oil poppy, the number of which increased. An increase in the content of carbohydrates in the vegetative organs of oil poppy plants under the action of chlormequat chloride was found to go along with a decrease in the content of total nitrogen in the roots and leaves both in the control sample and in the plants of the experimental variant.Conclusions. The usage of growth regulators in the budding phase causes an increase in the productivity of oil poppy and rapeseed culture. Under the action of these preparations, a correction of donor-acceptor relations in the plant is observed. It is implemented through the redistribution of assimilates from vegetative organs to the needs of carpogenesis. The formation of a more powerful acceptor sphere is associated with laying a larger number of fruits - the main acceptors of assimilates in the second half of the growing season. An increase in the load of the plant with fruits in the plants of the experimental variants also affected a more intensive flow of carbohydrates and nitrogen-containing compounds to them, which ultimately led to an increase in the seed yield.

Effect of 6-Benzylaminopurine on Morphogenesis and Production Process of Sweet Pepper (Capsicum annuum L.)

Effect of 6-Benzylaminopurine on Morphogenesis and Production Process of Sweet Pepper (Capsicum annuum L.)

Influence of gibberellin on the mesostructural organization of the leaf, accumulation and redistribution of assimilates and feeding elements of the gooseberry plants (Grossularia reclinat) in connection with the productivity of culture

The effect of gibberellic acid on morphogenesis, mesostructural leaf organization, accumulation and redistribution of various forms of carbohydrates, nitrogen, phosphorus and potassium between the organs of gooseberry plants of the Mashenka variety in relation to the productivity of the culture has been established. The aim of the study was to find out the peculiarities of morphogenesis, the formation of the leaf apparatus, the accumulation and redistribution of assimilates and nitrogen-containing compounds between the organs of gooseberry plants for the actions of gibberellic acid in connection with the productivity of the culture. Materials and methods. Plants were treated once during the budding period with a 0.05 % m gibireleic acid solution during the budding phase. The carbohydrate content was determined by the iodometric method, nitrogen - by Keldahl, phosphorus - by the intensity of the formation of the phosphorus-molifbdenovogo complex, potassium - by flame-photometric, the content of chlorophylls - spectrophotometrically. Results . Under the influence of the drug, a more powerful donor sphere was formed due to the growth of chlorenchyma due to an increase in the volume and linear dimensions of the cells of the columnar and spongy assimilation tissue. This led to enhanced assimilation, an increase in the content of non-structural carbohydrates (sugar + starch) in the shoots. Processing gibberellin contributed to the optimization of nitrogen, phosphorus and potassium in the leaves and shoots. A significant deponuvalous capacity of the stems in the temporary redundancy of an aksimilit and gooseberry plant nutrients with the subsequent reutilization of them to the processes of carpogenesis has been established. Changes in the nature of donor-acceptor relations in gooseberry plants under the influence of gibberellic acid caused the redistribution of assimilate and nutrient fluxes from vegetative organs to fruits, and had a positive effect on the crop productivity. Findings. The use of gibberellic acid led to the formation of a more powerful donor sphere, the accumulation and temporary deposit of the part of carbohydrates and mineral nutrients in the vegetative organs of gooseberry plants, followed by their remobilization on the need for fruit formation and growth, led to a significant increase in yield and improved the product quality

Features of morphogenesis, accumulation and redistribution of assimilate and nitrogen containing compounds in tomatoes under retardants treatment

<p>We studied the influence of ethylene product Esphon® and triazole derivative Folicur® on the morphogenesis and productivity of tomatoes. The obtained results explained the significant role of morphological and mesostructural components of “source-sink” relation system of tomatoes in the formation of crop productivity. We established that the Folicur application resulted in more significant anatomical and morphological changes in the formation of leaf apparatus in comparison with the ethylene producer: the measurement of number, weight, area of leaf surface, and leaf index were higher in this variant of experiment. We also noted the appropriate changes in the mesostructure measurement of leaves: thickness of leave – main photosynthetic tissue of chlorenchyma, assimilatory cells size of palisade and spongy parenchyma. Analysis of depositing possibilities of plants vegetative organs at the fruitification stage indicates the importance of temporary postponement of nonstructural carbohydrates and nitrogen containing compounds in them followed by reutilization for carpogenesis needs. Application of Folicur resulted on the formation of a more powerful donor sphere and in the early fruit growth and formation stages are postponed more carbohydrates in vegetative organs of tomato plants compared to control. The content of sugars and starch in the roots, stems and leaves of plants under Folicur treatment was highest in all organs of the plant throughout the fruitification phase compared to control and variant with Esphon application. Our results also testify to the possibilities of nitrogen compounds remobilize from vegetative organs to carpogenesis needs. After Folicur treatment, the most intense decrease in the content of nitrogen containing compounds was observed during the transition from the fruit formation stage to green fruits stage in roots and stem of plant during the period of the most intense tomatoes growth. We concluded that a significant increase the yield of tomato crop was caused by the more powerful donor sphere formation and reutilization of assimilates and nitrogen containing compounds after Folicur application.</p>

Особливості функціонування донорно-акцепторної системи маку олійного за дії трептолему в зв’язку з продуктивністю культури

<p>We studied the action of synthetic growth stimulator (treptolem) on the morphogenesis, leaf mesostructure, redistribution of assimilates, and nutrients between organs of oil poppy (<em>Papaver somniferum</em> <em>L.</em>) in ontogenesis, productivity and structure of crop. Optimization of production process of oil poppy under the influence of growth stimulator is realized through the source-sink relation system of the plant. Obtained results testify the essential role of morphological and mesostructural components in regulation of source-sink relation system of oil poppy. Appplcation of treptolem’s growth stimulating contributed the formation of more powerful donor sphere and increased the number and mass of leaves, the area of leaf surface and the leaf index. It was found that the reason of such morphological changes caused significant increase in branching of the stem by the action of treatment. The intensification of donor function poppy plants by treptolem also occurred as a result of mesostructural changes in the leaves. Treptolem application induced formation of a more powerful layer of chlorenchymes - the main photosynthetic tissues of plant, linear sizes of chlorenchymal cells and chlorophylls content increased in them. In that case, the intensification of growth processes at the beginning of vegetation under the influence of preparation led to forme a more powerful donor potential of the plant per unit of cenosis area, which created prerequisites to increase the productivity of culture. It was found that the consequence of such changes was an increase of the content of nonstructural carbohydrates (sugar + starch) in vegetative organs of treated variant in compared with the control of intense growth. Treatment showed apparent branching of the stems, that induced a larger number of flowers and fruitcases were laid an increase of acceptor capacity of plant. The result of these changes was determined by more intensive flow of nonstructural carbohydrates on the formation and growth of fruits in the variant with treptolem. In the flowering phase in the roots and leaves of plants, it was observed the highest content of nitrogen that during the formation and growth of the fruit was remobilized on the carpogenesis process. At the same time, the more intensively use of nitrogen by the vegetative organs of the poppy plants to form the fruitcases was in the variant with treptolem. It was noted the lower levels of phosphorus in the leaves and potassium in the vegetative organs of oil poppy in the variant of treptolem treated plant. It testifies that preparation treatment contributed to the more intensive reutilisation of nitrogen, phosphorus, and potassium compounds in fruit formation. The intensified flow of assimilates and nitrogen-containing compounds together with nutrients to a greater number of implanted fruits provided the growth of crop yields (by increase in the number of cases, the mass of seeds in case, and the mass of a single seed). It is confirmed that there is negative correlation between accumulation of oil and content of nitrogen. It was established that application of treptolem increased the content of unsaturated higher fatty acids in oil poppy. An important practical result of the research should be considered that treptolem treatment increased the content of alkaloids in the seeds of poppy plants, which could e useful in pharmacological industry. We proved that treptolem application during the budding period on the poppy seed leads to increase the yield of crop due to optimized morphological structure of plant, the mesosurface structure of leaf; it is also increased the potential trapping due to the laying and formation of a greater number of fruits.</p>

Factor model of formation of seed and green mass productivity in white lupine plants

Purpose. To study peculiarities of forming yield of seeds and green mass in white lupine. To identify the system of relationships between some elements of productivity and each factor share in the total variance of productive capa­city for developing breeding programs to create varieties for different uses Methods. Field investigation, laboratory tests, statistical analysis.Results. After processing initial data that concerned parameters of structural elements of seed and green mass yield among multiplicity characteristics of studied plants, new key factors were identified which were characterized by a number of basic traits. In terms of seed productivity, five key factors were defined that cause over 86% of the total variability. The first factor described the productivity of laterals, the second one – the productivity of the central raceme, the third one – redistribution of assimilates between vegetative and reproductive organs, the fourth one – microredistribution of assimilates in beans; the fifth one – the ability to form productive beans. Due to the analysis of the structure of green mass productivi­ty traits, four key factors were defined that described over 85% of the total variability: the first factor – the general growth and development; the second one – the productivi­ty of laterals; the third one – feeding value; the fourth one – the productivity of central raceme. Factor model allowed to identify basic traits and share of each system associated with a particular factor in the formation of the complex trait of the general plant productivity of white lupine. Conclusions. The factor model of the white lupine seed productivity formation included five key factors. The process of formation of vegetative productivity is characterized by four key factors. The variety factor model can be used for parental forms selection and assessment of new hybrid material.

Morphological and physiological responses of different wheat genotypes to chilling stress: a cue to explain yield loss.

The eco-physiological mechanism of wheat yield loss resulting from chilling stress is a fundamental scientific issue. However, previous studies have focused on hexaploid wheats, and few studies on the morphological and physiological plasticity of wheat plants. Six different wheat genotypes were tested under chilling stress to investigate the physio-morphological parameters as well as the loss of grain yield in growth chambers. Chilling stress resulted in significant loss in grain yield in all genotypes. Under chilling stress, diploid wheats generated zero harvest, and tetraploid genotypes also suffered from a pronounced loss in grain yield, compared with the control group. In contrast, hexaploid genotypes acquired relatively high maintenance rate of grain yield among three species. Diploid and tetraploid wheat genotypes maintained relatively large leaf area and high photosynthetic rates, but they were subjected to significant declines in vascular bundle number and productive tillers as a consequence of the inhibition by sink growth under chilling stress. The hexaploid wheats were found to have relatively low leaf area and photosynthetic rates. These genotypes also stored more soluble carbohydrates and exhibited stronger sink enhancement, ensuring the translocation and redistribution of assimilates. Our findings provided a new theoretical understanding of yield stabilization in the domestication process of wheat genotypes under chilling stress. © 2017 Her Majesty the Queen in Right of Canada. Journal of The Science of Food and Agriculture © 2017 Society of Chemical Industry.

Selection and Breeding of Suitable Crop Genotypes for Drought and Heat Periods in a Changing Climate: Which Morphological and Physiological Properties Should Be Considered?

Selection and breeding of genotypes with improved drought/heat tolerance become key issues in the course of global change with predicted increased frequency of droughts or heat waves. Several morphological and physiological plant traits must be considered. Rooting depth, root branching, nutrient acquisition, mycorrhization, nodulation in legumes and the release of nutrients, assimilates or phytohormones to the shoot are relevant in root systems. Xylem embolism and its repair after a drought, development of axillary buds and solute channeling via xylem (acropetal) and phloem (basipetal and acropetal) are key processes in the stem. The photosynthetically active biomass depends on leaf expansion and senescence. Cuticle thickness and properties, epicuticular waxes, stomatal regulation including responses to phytohormones, stomatal plugs and mesophyll resistance are involved in optimizing leaf water relations. Aquaporins, dehydrins, enzymes involved in the metabolism of compatible solutes (e.g., proline) and Rubisco activase are examples for proteins involved in heat or drought susceptibility. Assimilate redistribution from leaves to maturing fruits via the phloem influences yield quantity and quality. Proteomic analyses allow a deeper insight into the network of stress responses and may serve as a basis to identify suitable genotypes, although improved stress tolerance will have its price (often lowered productivity under optimal conditions).

Some of Defence Mechanisms and Breeding Prospects of Drought Stress Tolerance in Common Bean (Phaseolus vulgarisL.)

Most of the common bean production in the world takes place under rainfed conditions and drought due to insufficient or unpredictable rainfall limits yield. Nearly 60% of bean production occurs in agricultural land prone to water deficit, where the costs of irrigation or the lack of precipitation are major difficulties for producers. Consequently, there is an increasing need to improve drought tolerance in common bean cultivars, where adaptive mechanisms to cope with this main abiotic stress include characters such as root architecture, growth habit, maturity acceleration, early flowering, shoot biomass accumulation and efficient assimilate redistribution towards seeds, contributing to an increased harvest index. With projections of expanding and more frequent drought in many regions, the tepary bean has the potential of being a game-changing technology, providing farmers with an alternative but similar and equally nutritious bean crop that will enhance their resilience to pending climate change. This review will highlight some of the unique features of tepary bean as a promising source for amelioration of drought stress tolerance in common bean.

Early senescence of the oldest leaves of Fe‐deficient barley plants may contribute to phytosiderophore release from the roots

Barley (Hordeum vulgare), which tolerates iron (Fe) deficiency, secretes a large amount of phytosiderophores from its roots. However, how barley is able to allocate resources for phytosiderophore synthesis when the carbon assimilation rate is reduced by Fe deficiency is unknown. We previously suggested that the acceleration of senescence in older leaves triggered by Fe deficiency may allow the recycling of assimilates to contribute to phytosiderophore synthesis. In this work, we show the relationship between an increase in the C/N ratio in older leaves and Fe-deficiency tolerance among three barley cultivars. The increase in the C/N ratio suggests an enhanced capacity for the retranslocation of carbohydrates or amino acids from older leaves to the sink organs. An increase in the sucrose concentration in Fe-deficient barley also suggests active redistribution of assimilates. This metabolic modulation may be supported by accelerated senescence of older leaves, as Fe deficiency increased the expression of senescence-associated genes. The older leaves of Fe-deficient barley maintained CO2 assimilation under Fe deficiency. Barley that had been Fe-deficient for 3 days preferentially allocated newly assimilated (13) C to the roots and nutrient solution. Interestingly, the oldest leaf of Fe-deficient barley released more (13) C into the nutrient solution than the second oldest leaf. Thus, the balance between anabolism and catabolism in older leaves, supported by highly regulated senescence, plays a key role in metabolic adaptation in Fe-deficient barley.

Effect of Nitrogen and Defoliation on Assimilate Redistribution and Grain Yield of Maize (Zea mays L.) Under Subtropical Conditions

In order to study the effects of nitrogen levels and defoliation on grain yield, yield components, and assimilate redistribution in maize (single cross 704), a field experiment was conducted in south-west of Iran in 2010–2011. The experiment was split-plot in the form of randomized complete block design with three replications. Main plots consisted of four nitrogen rates (0, 80, 160 and 240 kg N ha−1) and elimination of some physiological resources including defoliation of upper and lower leaves of the canopy at anthesis stage and control (un-manipulated) were placed in sub-plots. Results indicated that the effect of nitrogen fertilizers and defoliation on grain yield was significant (P < 1 %), but the effect of nitrogen and defoliation interaction on this trait was not. The lowest and the highest grain yield belonged to 0 and 240 kg N ha−1, respectively. As compared to the un-manipulated treatment, grain yield was 22.2 and 4.2 % lower in defoliation of upper and lower leaves, respectively. Grain yield reduction in defoliation of upper leaves was due to significant reduction of the number of grains and their weight. As the nitrogen rates increased to 160 and 240 kg ha−1, stem assimilate redistribution increased and somewhat compensated for the effect of defoliation of lower leaves of the maize on its grain yield.

Changes induced by defoliation in the yield and digestibility of leaves and stems of perennial ryegrass ( Lolium perenne L.) during reproductive development

Ten identical perennial ryegrass plots (cv. Frances) were sequentially harvested for first cut silage at 7 day intervals, with second cuts after 6 weeks regrowth and further cuts until the growing season ended. Total herbage dry matter and digestible organic matter yields increased and digestibility decreased with delayed cutting, as was expected. The opposite and counterbalancing response occurred at the second cut. This pattern of yield change was mirrored by changes in the amount of stem tissue, whereas leaf yield did not change significantly at the first harvest but declined at the second, in response to delayed cutting. Furthermore, stem digestibility declined at the first cycle of harvests from ca. 75 to 62–64% in the most delayed cutting treatments. In contrast, leaf digestibility remained high (ca. 70%) until after seed-head emergence but then decreased rapidly to ca. 56%. This decline may have been associated with accelerated leaf senescence and redistribution of assimilates, though this needs to be examined. It was concluded that although manipulating first harvest date determined the proportioning of yield and digestibility in the first and second cuts, the observation that the combined yield and digestibility in these two harvests did not vary substantially is an important result for farming practice.

The Redistribution of Assimilate in Field-grown Winter Wheat

Les experiences relatees ont pour objet l'evolution et l'etude dynamique du stockage et de la remobilisation des assimilats au niveau des tiges de ble d'hiver cultive au champ. Cette etude, utilisant le 14 CO 2 comme traceur est effectuee a differents stages de developpement de la plante

Biomass production and gas exchange of winter wheat as affected by flag leaf inoculations with Septoria nodorum

summaryInoculation of flan leaves of winter wheat with Septoria nodorum (Berk.) Berk was more effective in reducing final grain weight when inoculation was at anthesis than when it was at flag leaf emergence, either during or following leaf expansion; grain number was not significantly affected by the timing of inoculation. The greatest senescence was observed with late inoculations with correspondingly lower flag leaf weight at grain maturity. It is suggested that flag leaves become more susceptible to S. nodorum with increasing time after emergence. Inoculation did not result in any significant redistribution of assimilate from stems to ears as it did not affect stem weight. The reduction in photosynthesis at high irradiance was proportional to infection‐induced senescence. Change in the total resistance to the diffusive flow of carbon dioxide was controlled by the mesophyll resistance, i.e. that remaining following subtraction of boundary layer and stomatal components.

Dry-season Legume Forages to Follow Paddy Rice in NE Thailand. III. Influence of Time and Intensity of Cutting on Crotalaria juncea

SUMMARYAn experiment at the University of Queensland studied the response of Crotalaria juncea to a single cut above node 4 or 10 at 6, 8 or 10 weeks after planting under long or short (inductive) daylengths. Initial deleterious effects of cutting on plant parts were in the sequence nodules &gt; roots &gt; shoots. Subsequent greater regrowth from plants cut earliest and at the higher node was associated with higher residual leaf area and negative growth rates were inferred below 90 cm2 pot−1. Redistribution of assimilate from stem to leaf production followed cutting; in inductive daylengths of 11.4 hours, flowering was delayed and the proportion of leaf increased from 21.0 to 32.4%. The high nitrogen content of leaf (3.5–5.3%) compared to stem (0.6–1.7%) indicated that early cutting was important in producing good quality hay.

Assimilate Redistribution from Soybean Pod Walls During Seed Development1

AbstractAccumulation of dry weight by soybean seeds occurs at a linear rate in spite of daily fluctuations in photosynthate production. This suggests a possible role for assimilate redistribution from storage in maternal fruit tissues to developing seeds. Because of their proximity to the seed, pod walls were suspected as temporary storage organs for photosynthate and nitrogenous assimilates.Populations of Norman (OO maturity) and Amsoy 71 (II maturity) soybeans [Glycine max (L.) Merr.] were field‐grown in 1977 on Cheshire fine sandy loam (Typic Dystrochrept). Weekly during reproductive growth, developing fruit were harvested and assimilates in pod walls extracted and colorimetrically determined. At midpodfilling, pods from three canopy strata were also harvested diurnally and analyzed. From the examination of dry weight and assimilate levels within these samples, evidence of storage and redistribution from pod walls was obtained.Prior to mid‐podfilling stage both cultivars accumulated maximum pod wall dry weight; Norman 290 mg pod wall‐1 on 11 August and Amsoy 71 170 mg pod wall‐1 on 25 August. Pod walls of Norman redistributed 112 mg of previously accumulated dry matter, occurring when incipient canopy senescence probably would have otherwise precluded continued linear seed growth. Assuming that these pod wall assimilates were transported to the enclosed seeds and an efficiency of conversion to seed of 41%, the redistributed materials accounted for 12.7% of the final seed yield per plant in Norman while only 1.8% in Amsoy 71.Pod walls were found to store and later redistribute starch, reducing sugars, and nitrogenous materials. The sucrose present was almost entirely in the major pod vascular bundles. Starch was a major storage product, but there was no significant diurnal variation in the amount. However, significantly more starch was accumulated by Norman pod walls in the upper third of the canopy. Glucose and fructose accumulations were depleted by redistribution in approximately the same time period as starch and nitrogenous materials.The data suggest that, in extremely short season cultivars such as Norman, assimilate storage and later redistribution by pod walls to the developing seeds may serve to effectively lengthen the period of podfilling and thus contribute significantly to final seed yield.

The influence of temperature and light intensity on grain growth in relation to the carbohydrate and nitrogen economy of the wheat plant.

The response of wheat grain growth to temp. and light intensity was studied under controlled conditions within the ranges 10-25 deg C and 64-188 W/m2, resp. Warmth hastened plant senescence and enhanced the initial growth rate of the grains. Additional light promoted the rate of grain growth more at high than at low temp.; under the latter conditions there was a considerable accumulation of carbohydrates in the stem (up to 40%) from anthesis onwards. The rate of grain growth ranged from 0.70 to 1.64 mg/day grain. The duration of grain growth was prolonged by decrease from 25 to 10 deg ; the increase in growth duration from about 30 to 80 days corresponded with a relatively stable temp. sum. Temp. and light also affected the redistribution of assimilates and the chemical composition of the grain. The rate of protein synthesis was promoted more by warmth than the rate of starch synthesis. This resulted in an increased N content of the grain. The final content of total non-structural carbohydrates (starch and sugars) was slightly decreased by warmth. Additional light raised the carbohydrate content of all parts of the plant and so decreased the N content of these parts. However, light intensity had less effect on N distribution and yield than temp. (Abstract retrieved from CAB Abstracts by CABI’s permission)