Stage Of Grain Research Articles

Glycolysis stimulation and storage protein accumulation are hallmarks of maize (Zea mays L.) grain filling

Maize (Zea mays L.) is a major dietary source of human caloric intake. Grain filling, the developmental stage of the seed during which starch and proteins accumulate, is of great interest in plant biology and agronomy. However, proteomic datasets covering maize seed development, especially during grain filling, are much scarcer than transcriptomic datasets, largely due to the labor-intensive and costly nature of the large-scale analysis required for proteomics. Here, we searched for proteins that showed changes in abundance during four time-points covering the middle stages of grain filling by two-dimensional electrophoresis, MALDI-TOF, and database searches. We detected 1384 protein spots, of which 48 exhibited differential accumulation during grain filling. Of those, we identified the underlying protein for 32 spots: they included enzymes of carbohydrate metabolism, stress-related proteins, and storage proteins, the latter of which represented 34% of all changing proteins during grain filling. Proteins related to carbohydrate metabolism reached their maximum accumulation around 15–20 days after pollination (DAP) and subsequently dropped until 30 DAP. The rise of stress-related proteins such as heat shock proteins demonstrated their involvement in grain filling and seed maturation. This study catalogues the proteome changes during grain filling and provides basic but critical information regarding the biological changes during maize kernel development.

Effects of water and nitrogen source types on soil enzyme activity and nitrogen utilization efficiency of wheat

To provide basis for high-yield and high-efficiency of wheat production, with two wheat cultivars, 'Zhengmai 366' (strong gluten) and 'Bainong 207' (medium gluten), we investigated the effects of four nitrogen source types, ammonium chloride (NT1), calcium nitrate (NT2), urea (NT3) and calcium ammonium nitrate (NT4), applied under two water treatments, no irrigation (W1) and irrigation at jointing and heading stages (W2), on soil N-supplying capacity, grain yield and nitrogen utilization efficiency. The results showed that content of soil ammonium and nitrate at flowering stage decreased with increasing soil depths. Compared with the corresponding value of 'Zhengmai 366' under W1 treatment, W2 treatment decreased the contents of soil ammonium and nitrate in the 0-60 cm layer, and enzymes activities of urease, invertase and catalase by 10.0%, 13.3%, 7.5%, 2.8%, and 3.9%, respectively. For the two wheat cultivars, the content of ammo-nium was significantly higher under NT1 and NT3 treatments than that of others, while the content of nitrate under NT2 and NT3 treatments was significantly higher than that of others. Additionally, NT3 and NT4 treatments increased soil urease and invertase activities at the middle and later stages of grain filling. Compared with NT1 treatment, NT3 and NT4 fertilization increased grain yield and nitrogen use efficiency of cultivar 'Zhengmai 366' by 14.9% and 20.7%, 25.6% and 13.9%, under W2 treatment, respectively. Soil nitrate content in the 0-20 cm layer and the ammonium content in the 20-40 cm layer were positively correlated with wheat grain yield and nitrogen utilization efficiency. Under both water conditions, applying urea and calcium ammonium nitrate improved soil enzyme activity at the middle and later stages of grain filling, which was beneficial for wheat yield and nitrogen use efficiency.

Higher yielding varieties of common buckwheat (Fagopyrum esculentum Moench) with determinate growth habit (single mutation det) manifest higher photosynthesis rate at stage of grain filling

Comparison of common buckwheat varieties with determinate vs. indeterminate growth habit reveals no differences in leaf photosynthesis rate at stage before flowering. However, at stage of seed filling the difference was significant. Maximal difference was 20 days after early flowering, i.e in period of most intensive seed formation. These results show that determinate varieties have higher sink strength providing by developing seeds. It is correlated with higher yield ability of such varieties. Probably, growth limitation resulting from det-mutation leads to some shifts in system of sink priorities of buckwheat plant and allows initiate the development of additional seeds. One more possible cause of alteration of the physiological parameters in determinate varieties is some optimization of plant structure: in terms of physiology the determinate buckwheat is a plant which is more similar to cereals than indeterminate buckwheat. However, underlying physiological changes accompanying the transition from indeterminate toward determinate growth in buckwheat remain almost unknown. Assumption about strong effect of det-mutation per se on photosynthesis rate was not supported in our work. Alternative assumption about accumulation of additional genes enhancing the sink ability suggests opportunities for additional progress in the selection work using tools evaluating photosynthesis intensity at stage of grain filling.

Cultivo de milho crioulo para silagem em sistemas tradicional e agroflorestal

Avaliou-se a produção e a qualidade da silagem de milho crioulo produzida no sistema no sistema agroflorestal (SAF) em comparação ao produzido no tradicional (ST). O delineamento experimental foi inteiramente casualizado, com dois tratamentos e seis repetições. A ensilagem foi feita em silos experimentais de laboratório. Foram realizadas avaliações físicas e organolépticas (proporção de grãos, odor, cor, umidade e tamanho de partícula), determinação dos parâmetros agronômicos (estádio dos grãos, altura, número de folhas seca e peso das frações das plantas) e do teor de matéria seca (MS). A altura das plantas variou nos sistemas ST e SAF, sendo 15,55% superior no ST. No ST o componente colmo teve maior participação na massa da planta (49,41%), seguido das folhas (25,96%) , superando os valores obtidos no SAF. Os valores de MS no colmo (23,48%), folha (40,65%), palha (37,73%), sabugo (31,63%) e grãos (32,28%) das plantas colhidas no ST foram inferiores aos verificados no SAF, que apresentou, respectivamente para essas frações 26,72, 59,37, 66,09, 44,30 e 43,04%. Os teores de MS das silagens de milho (planta inteira) não diferiram entre os dois sistemas, sendo de 31,35% para o ST e de 33,06% para o SAF, com teor médio de 32,2%. O cultivo de milho no SAF apresenta menor potencial de produção da fração fibrosa (colmo e folhas) do que no ST, porém verificou-se maior produção de grãos no SAF. A silagem produzida apresentou teor de MS adequado em ambos os sistemas.

Modulation of Polyamines during Grain Development under Different Concentrations of Nitrogen in Wheat

The polyamine (PAs), putrescine (Put), spermidine (Spd) and spermine (Spm) are small aliphatic amines that ubiquitous in all living organisms. PA metabolism in higher plants is involved in both biotic and abiotic stress responses, and also influenced by nutrient deficiency. Accumulated evidence suggests that in plants the cellular titers of PAs are affected by various nitrogenous compounds. Therefore, the present study analyzed the effects of different nitrogen levels viz. recommended doses of nitrogen (RDN, 120 kg N/ha), sub-optimal N dose (RDN −25%, 90 kg N/ha) and supra-optimal N dose (RDN +25%, 150 kg N/ha) on PA metabolism in grains of six wheat genotypes at 15 days post anthesis (DPA) and 30 DPA. The activities of polyamine synthesizing enzymes (arginine decarboxylase, ornithine decarboxylase), catabolizing (diamine oxidase, polyamine oxidase) and the PA content were increased at supra-optimal nitrogen dose as compared to RDN. Whereas at sub-optimal nitrogen dose, higher activity of polyamine catabolizing enzymes results in speeding up oxidation of various PAs to cope up with nitrogen deficiency in plant. In relation to PA content, Put was found to be higher at early stage whereas Spd and Spm were found to be higher towards mature stages of grain indicating the use of Put in grain filling process. Highly significant correlation was observed between PA metabolism, yield and nitrogen use efficiency at sub-optimal N dose as compared to supra-optimal dose.

Use of X-ray micro computed tomography imaging to analyze the morphology of wheat grain through its development

BackgroundWheat is one of the most important staple source in the world for human consumption, animal feed and industrial raw materials. To deal with the global and increasing population demand, enhancing crop yield by increasing the final weight of individual grain is considered as a feasible solution. Morphometric analysis of wheat grain plays an important role in tracking and understanding developmental processes by assessing potential impacts on grains properties, size and shape that are major determinants of final grain weight. X-ray micro computed tomography (μCT) is a very powerful non-invasive imaging tool that is able to acquire 3D images of an individual grain, enabling to assess the morphology of wheat grain and of its different compartments. Our objective is to quantify changes of morphology during growth stages of wheat grain from 3D μCT images.Methods3D μCT images of wheat grains were acquired at various development stages ranging from 60 to 310 degree days after anthesis. We developed robust methods for the identification of outer and inner tissues within the grains, and the extraction of morphometric features using 3D μCT images. We also developed a specific workflow for the quantification of the shape of the grain crease.ResultsThe different compartments of the grain could be semi-automatically segmented. Variations of volumes of the compartments adequately describe the different stages of grain developments. The evolution of voids within wheat grain reflects lysis of outer tissues and growth of inner tissues. The crease shape could be quantified for each grain and averaged for each stage of development, helping us understand the genesis of the grain shape.ConclusionThis work shows that μCT acquisitions and image processing methodologies are powerful tools to extract morphometric parameters of developing wheat grain. The results of quantitative analysis revealed remarkable features of wheat grain growth. Further work will focus on building a computational model of wheat grain growth based on real 3D imaging data.

Studies on foliar application of zinc as bio-fortification strategy to enhance grain zinc content in rice (Oryza sativa L.) genotypes

Zinc (Zn) deficiency is a concern for nearly half of the world population. Biofortification through foliar Zn application is an approach to reduce human Zn deficiency. Knowledge available on effect of foliar applied zinc towards biofortification efficiency and bioavailability of rice grain is limited. Pot experiment with rice was conducted to study the effect of foliar applied zinc along with soil application of recommended dose of N: P: K: Zn for rice. Two contrasting groups of four cultivars each with respect to seed zinc based on previous screening were selected (high seed zinc types and low seed zinc types). Zinc was applied in the form of ZnSO4.7H2O foliar application at vegetative stage and at reproductive stage in three different doses (recommended dose, 10% lower than recommended dosage and 10% higher than recommended dosage). Results suggest that foliar zinc application is effective in enhancing grain zinc when applied with recommended dose of soil zinc fertilizer irrespective of inherent zinc acquisition capacity by roots. Stem had higher Zn accumulation at 65 DAS indicating translocation of foliar applied zinc. At 50% panicle initiation stage, there was higher zinc in leaf compared to stem and developing grain implying Zn movement from stem to seed. Zn analyzed at different stages of grain filling till harvest showed an increase in Zn content both in high and low zinc types. Higher seed Zn was observed in long duration varieties. Using long duration varieties for foliar biofortification could be an effective strategy to overcome Zn deficiency.

Study on stripe rust (Puccinia striiformis) effect on grain filling and seed morphology building of special winter wheat germplasm Huixianhong.

Stripe rust, caused by Puccinia striiformis f. sp. tritici (Pst), is an airborne fungal disease which always destructs leaf and leads to stagnation of grain filling, decreasing of kernel weight, thin seed and yield loss. Winter wheat Huixianhong is a special germplasm with special characteristics of tolerance or resistance against stripe rust. In order to understand the effect on Huixianhong from stripe rust, we designed two kinds of treatment, inoculation of stripe rust fungi (IH) and artificial immune by bactericide (CK) to study the dynamic of disease process, the grain filling and the thousand-kernel weight (TKW). Our results showed that the incubation period of Hongxinahui was 13.5 days. The prevalence increased from 32.9% at 15 days after jointing to 80.0% at 9 days after booting, and reached to 97.0% at the heading stage. The infection type (IT) was 7 to 9 at the beginning of anthesis. The severity, leaf withered area ratio and disease index at the 15th day after anthesis were 67.17%, 98.17% and 0.6717, respectively. The IH maximum increasing rate of leaf necrosis and chlorosis area was from heading beginning stage to anthesis beginning stage, which increased from 18.66 mm2·d-1 to 21.04 mm2·d-1. The maximum rate of grain filling was 1.25 mg·d-1 at the 18th day after anthesis, which was earlier than that of CK by 3.3 days. The IH thousand-kernel weight Loss (TKWL) was more than that of CK by 6.19%, the stage of heading and amature were 3.0 days and 4.5 days earlier than CK, respectively. The stripe rust infection seriously destructed the photosynthetic function of leaf at the earlier stage of grain filling, i.e. at the beginning of anthesis, which led to the most important biomass loss and the grain filling rate decrease. As far as stripe rust is concerned, Huixianhong is a high susceptible, easily been infected, seriously showing symptoms and most quickly epidemic type but can successfully complete grain filling in high quality. It is a very useful germplasm for creating and selecting special breeding materials against stripe rust.

OsNAC-like transcription factor involved in regulating seed-storage protein content at different stages of grain filling in rice under aerobic conditions

In this study, we show that NAC-like transcription factor (TF) has 90% sequence similarity with cDNA of the OsNac5 gene present in the NCBI database. Phylogenetic analysis of the NAC gene family was performed with inclusion of the highly diverse C-terminal sequences. We report that this gene is also found to be orthologous to Glycine max NAC8, NAC2, Triticum aestivum NAC6 and paralogous to OsNAC6. mRNA was purified from five recombinant inbred lines (RILs) and parents of rice at three different stages of grain filling under aerobic conditions, with grain protein content (GPC) spanning from 4 to 14%. The NAC-like TF encoding a protein was found to be upregulated at the S2 stage in the leaf (3.9-fold) and panicle (1.84-fold) of parent HPR14 and in five RILs (1.9 to 4.51-fold in leaves and 0.47 to 3.2-fold in panicles). Expression analysis of the NAC-like TF encoding a protein for the rice gene was found to be upregulated at the S2 stage in the leaf and panicle of parental line HPR14 and RILs with high protein content.

Transcriptional response of rice flag leaves to restricted external phosphorus supply during grain filling in rice cv. IR64.

Plant phosphorus (P) remobilisation during leaf senescence has fundamental implications for global P cycle fluxes. Hypothesising that genes involved in remobilisation of P from leaves during grain filling would show altered expression in response to P deprivation, we investigated gene expression in rice flag leaves at 8 days after anthesis (DAA) and 16 DAA in plants that received a continuous supply of P in the nutrient solution vs plants where P was omitted from the nutrient solution for 8 consecutive days prior to measurement. The transcriptional response to growth in the absence of P differed between the early stage (8 DAA) and the later stage (16 DAA) of grain filling. At 8 DAA, rice plants maintained production of energy substrates through upregulation of genes involved in photosynthesis. In contrast, at 16 DAA carbon substrates were produced by degradation of structural polysaccharides and over 50% of highly upregulated genes in P-deprived plants were associated with protein degradation and nitrogen/amino acid transport, suggesting withdrawal of P from the nutrient solution led to accelerated senescence. Genes involved in liberating inorganic P from the organic P compounds and vacuolar P transporters displayed differential expression depending on the stage of grain filling stage and timing of P withdrawal.

Interactive effects of plastic film mulching with supplemental irrigation on winter wheat photosynthesis, chlorophyll fluorescence and yield under simulated precipitation conditions

Water shortages continuously threaten agricultural productivity in semi-arid regions. Efficient water-saving management practices urgently need to be developed. In the present study, a mobile rain shelter was used with two cultivation modes: (1) the ridge furrow (R) rainfall harvesting system; and (2) traditional flat planting (F). In addition, two supplemental irrigation levels (150, 75 mm) and three precipitation levels (1: 275, 2: 200, 3: 125 mm) were included in this study. We demonstrated that the R system with 150 mm supplemental irrigation and 200 mm simulated rainfall can significantly improve winter wheat net photosynthesis rate (Pn), electron transport rate (ETR), effective quantum yield of PS II (ΦpsII), maximum quantum efficiency of PSII (Fv/Fm), variable fluorescence (Fv), energy transformation potential of PSII (Fv/Fo), and leaf photosynthetic performance index of PSⅡ (Fv/Fmʹ), at the jointing, flowering, and later stage of grain filling. These improvements were due to significantly increased soil moisture content, total chlorophyll ab contents (13.1%), and chlorophyll stability index (88.3%) of flag leaves, and decreased (32.7%) evapotranspiration (ET) at field scales and soil temperature, all of which increased the grain yield (18.9%) and water use efficiency (WUE, 75.8%) compared with traditional flat planting. The chlorophyll fluorescence parameters of winter wheat were significantly positively correlated with the Pn, total Chl, WUE, and grain yield (except ET). These results suggest that the R system with 150 mm supplemental irrigation and 200 mm simulated rainfall was the best cultivation practice for improving photosynthesis, chlorophyll fluorescence, WUE, and yield of winter wheat in semi-arid regions.

Determination of amylose content and expression analysis of the Granular-Bound Starch Synthase I (GBSS1) gene in rice grains

The study determined amylose content and expression level of GBSS I gene in rice grain. A total of eighteen (18) rice ( Oryza sativa L) cultivars of Indica varieties were collected from the National Rice Research Institute (NRRI) Cuttack and screened for their percentage amylose contents. Three cultivars namely Bindli, Naveen and Pooja which had contrasting characters in percentage amylose were then planted and used for the expression analysis. In the first stage of grain filling Bindli had 0.27 fold expression while Pooja and Naveen had 1.72 and 1.44 respectively. There was dramatic increase in the expression levels of the gene in the middle stage of grain filling in all the three cultivars with relative folds of 10.97, 42.71 and 27.34 recorded in Bindli, Pooja and Naveen respectively. However, at the last stage of grain filling, GBSS1 expression was low compared to the second stage with expression folds of 7.12, 7.55 and 1.67 in Bindli, Pooja and Naveen cultivars respectively. On the whole, Bindli cultivar showed lowest expression of the gene (GBSS1) when compared to Pooja and Naveen. Key words: rice gene, amylose, expression analysis, GBSS1

Remobilisation of phosphorus fractions in rice flag leaves during grain filling: Implications for photosynthesis and grain yields.

Phosphorus (P) is translocated from vegetative tissues to developing seeds during senescence in annual crop plants, but the impact of this P mobilisation on photosynthesis and plant performance is poorly understood. This study investigated rice (Oryza sativa L.) flag leaf photosynthesis and P remobilisation in a hydroponic study where P was either supplied until maturity or withdrawn permanently from the nutrient solution at anthesis, 8 days after anthesis (DAA) or 16 DAA. Prior to anthesis, plants received either the minimum level of P in nutrient solution required to achieve maximum grain yield (‘adequate P treatment’), or received luxury levels of P in the nutrient solution (‘luxury P treatment’). Flag leaf photosynthesis was impaired at 16 DAA when P was withdrawn at anthesis or 8 DAA under adequate P supply but only when P was withdrawn at anthesis under luxury P supply. Ultimately, reduced photosynthesis did not translate into grain yield reductions. There was some evidence plants remobilised less essential P pools (e.g. Pi) or replaceable P pools (e.g. phospholipid-P) prior to remobilisation of P in pools critical to leaf function such as nucleic acid-P and cytosolic Pi. Competition for P between vegetative tissues and developing grains can impair photosynthesis when P supply is withdrawn during early grain filling. A reduction in the P sink strength of grains by genetic manipulation may enable leaves to sustain high rates of photosynthesis until the later stages of grain filling.

High Precision Temperature Controlling AGPase in Wheat Affecting Yield and Quality Traits

Adenosine diphosphate glucose pyrophosphorylase (AGPase) is the rate limiting enzyme of starch biosynthesis that directly affects the wheat productivity. AGPase and grain growth rate (GGR) discerned to be following strict temperature regimen in wheat disomic chromosome substitution (DCS) lines. The first half of grain filling period had chromosome 1B and 2D as prominent players, whereas second half was mainly controlled by chromosomes 6A and 5B. Chromosome 2D had major contribution towards yield in a specific temperature range of 23 ± 1.5 °C during initial stages of grain filling which can serve as an effective early screening tool for terminal heat tolerance in wheat. Chromosome 2D with highest amylose content can also be utilized to produce low digestibility flour. Grain yield was found to be significantly associated with spikes/plant, grains/spike, grain weight/spike and plant biomass. Further, path analysis indicated that though grains/spike had less direct effect on grain yield but its indirect impact on grain yield via AGPase-21 activity was high.

Effect of high temperature on early stage of grain filling period in wheat (Triticum aestivum L.)

Effect of high temperature on early stage of grain filling period in wheat (Triticum aestivum L.)

Isolation of tissues and preservation of RNA from intact, germinated barley grain.

Isolated barley (Hordeum vulgare L.) aleurone layers have been widely used as a model system for studying gene expression and hormonal regulation in germinating cereal grains. A serious technological limitation of this approach has been the inability to confidently extrapolate conclusions obtained from isolated tissues back to the whole grain, where the co-location of several living and non-living tissues results in complex tissue-tissue interactions and regulatory pathways coordinated across the multiple tissues. Here we have developed methods for isolating fragments of aleurone, starchy endosperm, embryo, scutellum, pericarp-testa, husk and crushed cell layers from germinated grain. An important step in the procedure involves the rapid fixation of the intact grain to freeze the transcriptional activity of individual tissues while dissection is effected for subsequent transcriptomic analyses. The developmental profiles of 19611 gene transcripts were precisely defined in the purified tissues and in whole grain during the first 24h of germination by RNA sequencing. Spatial and temporal patterns of transcription were validated against well-defined data on enzyme activities in both whole grain and isolated tissues. Transcript profiles of genes involved in mitochondrial assembly and function were used to validate the very early stages of germination, while the profiles of genes involved in starch and cell wall mobilisation matched existing data on activities of corresponding enzymes. The data will be broadly applicable for the interrogation of co-expression and differential expression patterns and for the identification of transcription factors that are important in the early stages of grain and seed germination.

Regulation of Gene Expression in the Remobilization of Carbon Reserves in Rice Stems During Grain Filling.

Carbon reserves in rice straw (stem and sheath) before flowering contribute to a significant portion of grain filling. However, the molecular mechanism of carbon reserve remobilization from straw to grains remains unclear. In this study, super rice LYP9 and conventional rice 9311 showed different carbon reserve remobilization behaviors. The transcriptomic profiles of straws of LYP9 and 9311 were analyzed at three stages of grain filling. Among the differentially expressed genes (DGs), 5,733 genes were uniquely up- or down-regulated at 30 days after anthesis (DAA) between LYP9 and 9311 in comparison with 681 at 10 DAA and 495 at 20 DAA, suggesting that the gene expression profile of LYP9 was very different from that of 9311 at the late stage of grain filling. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis and Gene Ontology (GO) classification of DGs both showed that the carbohydrate catabolic pathway, plant hormone signal transduction and photosynthesis pathway were enriched in DGs, suggesting their roles in carbon reserve remobilization, which explains to a certain extent the difference in non-structural carbohydrate content, photosynthesis and ABA content between the two cultivars during grain filling. Further comparative analysis and confirmation by quantitative real-time PCR and enzyme assays suggest that genes involved in trehalose synthesis (trehalose-phosphate phosphatase and trehalose 6-phosphate synthase/phosphatase), starch degradation (β-amylase) and sucrose synthesis (sucrose-phosphate synthase and sucrose synthase) were important for carbon reserve remobilization, whereas ABA content was determined by the counteraction of NCED1 and ABA8ox1 genes. The higher expression level of all these genes and ABA content in 9311 resulted in better efficiency of carbon reserve remobilization in 9311 than in LYP9.

Effects of supplemental irrigation based on soil moisture levels on photosynthesis, dry matter accumulation, and remobilization in winter wheat (Triticum aestivum L.) cultivars

Two winter wheat (Triticum aestivum L.) cultivars, namely Jimai22 (JM22) and Zhouyuan9369 (ZY9369), were used to study the effects of a new irrigation policy, supplemental irrigation (SI) based on soil moisture levels, photosynthesis, dry matter accumulation, and remobilization from 2009 to 2011 in Northern China. Two SI treatments were designed based on relative soil moisture contents in the 0–140 cm soil layer: (1) the target soil relative water contents were 75% of field capacity (FC) at jointing and 65% of FC at anthesis (W1), 75% and 70% (W2) in 2009–2010, and (2) the target soil relative water contents were 75% at jointing and 75% at anthesis (W1′), 75% and 80% (W2′) in 2010–2011. Rain-fed treatment (W0) was used as control. Results showed that SI significantly improved the biomass, grain yield and water use efficiency (WUE) of both wheat cultivars. The biomass and grain yield of W1 and W1’ treatments were higher than those of others. The net photosynthetic rate, the actual photochemical efficiency of flag leaf, the accumulation of dry matter, and its remobilization from the vegetative parts to the grains after anthesis in W1 and W1’ treatments were significantly higher than in the other treatments. By contrast, the WUE and irrigation efficiency of W2 and W2’ were significantly lower than those of W1 and W1’. Under the experimental conditions, ‘JM22’ showed higher photosynthetic rate in the last stage of grain filling, more spike number per ha, more kernels per spike, higher 1000-kernels weight and eventually higher WUE than ‘ZY9369’.

Photosynthesis and Drymass Production of Winter Wheat in Response to Micro‐Sprinkling Irrigation

Core Ideas Supplemental irrigation with micro‐sprinkling hose was suitable for wheat. The Fv/Fm, ΦPSII, and photosynthetic rate increased with increased hose sprinkling angle. Supplemental irrigation with 80° sprinkling angle hose increased dry matter, grain‐filling rate, and duration. All benefits were hypothesized to accrue through the increased soil water uniformity. Water‐saving irrigation techniques are critical for winter wheat (Triticum aestivum L.) development in the Huang‐Huai‐Hai Plain of China and assist in coping with increasingly serious water shortages. A micro‐sprinkling irrigation experiment was conducted from 2010 to 2012 to investigate how soil water distribution, photosynthesis, drymass accumulation, and grain yield responded to different sprinkling angles. Five treatments were designed: Rainfed, W35, W50, W65, and W80. The Rainfed treatment consisted of no irrigation throughout the growing season. The W35 to W80 treatments involved irrigation applied through micro‐sprinkling hoses with sprinkling angles of 35°, 50°, 65°, and 80°, respectively. Micro‐sprinkling irrigation could regulate soil water content to the target level of previous designs. After irrigation, distribution of soil water across the four inter‐rows was the most uniform in W80. Following the intermediate stage of grain filling, when increasing sprinkling angle from 35° to 80°, the mean actual photochemical efficiency, maximum quantum yield of the PSII, flag leaf photosynthetic rate, and canopy apparent photosynthetic rate (CAP) significantly increased. A high sprinkling angle is favorable in improving the grain‐filling rate as well as lengthening its duration. At maturity, the W80 treatment produced the highest dry matter (DM) in the stem plus sheath and the highest grain weight and total DM, leading to the highest 1000‐grain weight, grain yield, and water‐use efficiency (WUE). Overall, the optimum sprinkling angle of the micro‐sprinkling hose for supplemental irrigation (SI) of winter wheat after jointing is 80°, and the benefits are hypothesized to arise from an increased uniformity of soil water conditions.

Variation in Polyamine Content among 12 Pollinated Wheat Genotypes under Drought Stress Condition

The present work aims to study the drought stress effects on polyamine content and its relationship with growth and development in seeds, during cell division (from the beginning and until 17 days after pollination) and grain filling (until reaching the physiological maturity) stages. Factorial experiment based on Randomized Complete Block (RCB) design was carried out with three replications. Two factors of the experiment were considered: the level of irrigation (irrigation without and with drought stress during cell division stage and with drought stress during grain filling stage) and the level of wheat genotype (drought-resistant, semi-resistant and sensitive genotypes). As control treatment, soil moisture content of the field was considered. For drought-stress treatment, the 50% of the soil moisture content in control treatment was established. According to the experimental results, Putrescine content value is higher in control treatment which develops seeds of drought-resistant genotypes than that are registered for semi-resistant and sensitive genotypes. Both drought stress treatments induced significant rises in putrescine amount in the different genotypes of the study. The rises of putrescine content in sensitive and semi-resistant genotypes, however, were higher than in resistant ones, and the highest rise in putrescine content appeared in manning semi-resistant genotype during the stage of grain filling (27 days after pollination). Exerting drought stress in both stages of cell division and grain filling led to significant increase in spermine and spermidine contents of developing seeds of entire genotypes of the study. The highest spermidine content during grain filling stage occurred in sensitive genotypes of Shark and Tevee’s, and the lowest occurred in semi-resistant genotype of Sabalan. The highest spermine content during cell division stage, though, happened in semi-resistant genotype of manning. In fact, spermine and spermidine act as analogous to plant hormones such as Auxin and Cytokine, or they cooperate with these hormones in order to take a role in cell division regulation of developing wheat seeds and development of sink strength. They, additionally, stabilize the cell division process of developing seeds under drought condition. According to the findings of the study, manning semi-resistant genotype is capable of having a high grain yield under drought condition by reason of reserving high amounts of polyamines.