Dry Matter Accumulation In Grain Research Articles

Influence of Exogenous 28-Homobrassinolide Optimized Dosage and EDAH Application on Hormone Status, Grain Filling, and Maize Production

Exogenously applied phytohormones improve the endosperm cells and establish greater kernel sink capacity and grain filling, improving grain yield. In this study, 28-Homobrassinolide (HBR) dosages (20, 25, and 30 mg a. i. ha−1) were applied separately at the silking stage under controlled conditions, and EDAH (a mixture of ethephon and diethyl aminoethyl hexanoate) dosage of 90 g a. i. ha−1 was sprayed at the jointing stage to enhance the lodging resistance. Our objective was to investigate whether the application of HBR under controlled conditions or with EDAH could enhance the grain filling rate by regulating endogenous hormones. The results showed that HBR at the silking stage significantly increased endogenous hormones (ABA, IAA, Z+ZR), hampered leaf senescence, enhanced photosynthetic, improved dry matter accumulation in grains, and increased the grain-filling period, filling rate, and thousand-grains weight. Additionally, HBR 25 and 30 mg a. i. ha−1 increased the final yield by 9.9% and 19.5% compared to the control (CK) in 2020 and 14.1% and 18.95% in 2021, respectively. There was no significant difference between the results obtained from HBR-controlled and EDAH treatments at the jointing stage. Thus, we conclude that spraying HBR 25~30 mg a. i. ha−1 under controlled conditions may increase the grain yield under normal weather conditions. In adverse weather conditions and heavy wind, spraying EDAH 90 g a. i. ha−1 at the jointing stage and HBR 30 mg a. i. ha−1 at the silking stage can enhance maize production.

The effect of source–sink on yield and water use of winter wheat under ridge-furrow with film mulching and nitrogen fertilization

Ridge-furrow with plastic film mulching and nitrogen fertilization has been shown to improve soil conditions and plant growth, but it is still unclear how the above-mentioned agronomic practices regulate carbon assimilating (source) and carbon reservoir (sink) to increase winter wheat yield and water use. A field trial was conducted with planting patterns (flat planting with non-mulching (FP) and ridge-furrow with plastic film mulch (RP)) as main plots and N rates (0, 90, 180, and 270 kg N ha–1, marked as N0, N1, N2, and N3, respectively) as sub-plots. The results showed that RP significantly increased soil water storage (SWS), soil temperature (except that at the milk and dough stages of the 2019–2020 season), net content of soil mineral N, and consumption of soil mineral N by 3.8%− 13.5%, 1.4–5 ℃, 7.2%− 197.9%, and 15.1%− 595.7%, respectively, but significantly decreased evapotranspiration during the growth stages (ETi), total ET (ETTotal) of 2019–2020, and WUE by 9.90%, 7.28%, and 11.52%, respectively, compared with FP. Nitrogen application significantly decreased SWS and soil temperature by 9.3%− 22.9% and 5.1%− 21.1%, but increased net content of soil mineral N, consumption of soil mineral N, ETi, ETTotal, and WUE by 45.9%− 512.4%, 15.0%− 22.0%, 6.0%− 50.3%, 8.98%− 25.32%, and 38.50–145.75%, respectively, compared with N0. Soil water storage at the anthesis, milk, and dough stages and soil temperature at the milk stage mainly increased the source and establishment of the initial reservoir, while the soil mineral N mainly optimized the source-sink balance in the middle and late period. However, leaf area and dry matter at anthesis, chlorophyll content at 18 days post-anthesis, and grain number, especially spike number, played decisive roles in increasing yield, while leaf area and dry matter at the milk stage, grain volume at 30 days post-anthesis, and especially the post-anthesis contribution rate for dry matter accumulation in grains, were the main limiting factors. Therefore, ridge-furrow with plastic film mulching combined with 180 kg N ha−1 could balance the source-sink, but it is necessary to study the ratio of ridge-furrow and sowing rate to achieve a high yield and WUE.

Carbohydrate Assimilation and Translocation Regulate Grain Yield Formation in Wheat Crops (Triticum aestivum L.) under Post-Flowering Waterlogging

In a two-year field study, we quantified the impact of post-flowering soil waterlogging on carbon assimilation and grain yield formation in wheat crops. At anthesis, wheat cultivars YangMai 18 (YM18) and YanNong 19 (YN19) were waterlogged for different durations, i.e., 0 (W0), 3 (W3), 6 (W6) and 9 (W9) days using artificial structures. Changes in leaf physiology, carbon assimilation and biomass production were quantified at 0, 7, 14, and 21 days after anthesis under all treatments. Short-term (W3) waterlogging had no significant effect on wheat crops but W6 and W9 significantly reduced the net photosynthetic rate (Pn), leaf SPAD value, and grain weight of the tested cultivars. Increasing waterlogging duration significantly increased dry matter accumulation in the spike-axis + glumes but reduced dry matter accumulation in grain. Further, the tested cultivars responded significantly variably to W6 and W9. Averaged across two years, YM 18 performed relatively superior to YN19 in response to long-term waterlogging. For example, at 14 days after anthesis, W9 plants of YM18 and YN19 experienced a 17.4% and 23.2% reduction in SPAD and 25.3% and 30.8% reduction in Pn, respectively, compared with their W0 plants. Consequently, YM18 suffered a relatively smaller grain yield loss (i.e., 16.0%) than YN19 (23.4%) under W9. Our study suggests that wheat cultivar YM18 could protect grain development from waterlogging injury by sustaining assimilates supplies to grain under waterlogged environments.

Conservation tillage increases yield and precipitation use efficiency of wheat on the semi-arid Loess Plateau of China

Drought is a major limiting factor for rainfed spring wheat production on the semiarid Loess Plateau of China. Suitable tillage practices are important for improving precipitation use efficiency (PUE), which is the ratio of grain yield to annual precipitation. To obtain a better understanding of the effects of conservation tillage practices on PUE on the semiarid Loess Plateau, PUE was divided into five steps: precipitation storage efficiency, farmland water consumption rate, ratio of transpiration to evapotranspiration, crop transpiration efficiency, and harvest index. Six tillage practices were assessed in this paper, including conventional tillage with no straw (T), no-till with straw cover (NTS), no-till with no straw (NT), conventional tillage with straw incorporated (TS), conventional tillage with plastic mulch (TP), and no-till with plastic mulch (NTP), based on a long-term experiment initiated in 2001. The impact of tillage practices on soil quality, soil water storage, soil evaporation, biomass yield, and grain yield of spring wheat were monitored in 2015 and 2016. The results show that NTS improved soil quality and soil water storage before sowing. No-till with plastic mulch and NTS increased evapotranspiration but decreased evaporation, thus optimizing precipitation storage efficiency, the farmland water consumption rate, the ratio of transpiration to evapotranspiration, and crop transpiration efficiency, which gave rise to greater aboveground dry matter accumulation and more dry matter accumulation in grain. As a result, grain yield under NTS and NTP was significantly increased by 45 and 41 % compare to T, respectively, with corresponding improvements in PUE of 43 and 39 %. Therefore, both NTS and NTP have potential to substantially increase grain yield of spring wheat and PUE. However, for sustainable intensification in the long-run, NTS is the best combination of tillage and soil surface management for spring wheat production on the semi-arid Loess Plateau of China.

CN-Wheat, a functional-structural model of carbon and nitrogen metabolism in wheat culms after anthesis. II. Model evaluation.

Background and Aims Simulating resource allocation in crops requires an integrated view of plant functioning and the formalization of interactions between carbon (C) and nitrogen (N) metabolisms. This study evaluates the functional-structural model CN-Wheat developed for winter wheat after anthesis. Methods In CN-Wheat the acquisition and allocation of resources between photosynthetic organs, roots and grains are emergent properties of sink and source activities and transfers of mobile metabolites. CN-Wheat was calibrated for field plants under three N fertilizations at anthesis. Model parameters were taken from the literature or calibrated on the experimental data. Key Results The model was able to predict the temporal variations and the distribution of resources in the culm. Thus, CN-Wheat accurately predicted the post-anthesis kinetics of dry masses and N content of photosynthetic organs and grains in response to N fertilization. In our simulations, when soil nitrates were non-limiting, N in grains was ultimately determined by availability of C for root activity. Dry matter accumulation in grains was mostly affected by photosynthetic organ lifespan, which was regulated by protein turnover and C-regulated root activity. Conclusions The present study illustrates that the hypotheses implemented in the model were able to predict realistic dynamics and spatial patterns of C and N. CN-Wheat provided insights into the interplay of C and N metabolism and how the depletion of mobile metabolites due to grain filling ultimately results in the cessation of resource capture. This enabled us to identify processes that limit grain mass and protein content and are potential targets for plant breeding.

Variation of Wheat Cultivars in Their Response to Elevated Temperature on Starch and Dry Matter Accumulation in Grain

Three wheat cultivars, namely, BARI Gom 25, BARI Gom 26, and Pavon 76, were sown in experimental field of Bangabandhu Sheikh Mujibur Rahman Agricultural University, Gazipur, in Bangladesh, on 18 November, 2013. Two temperature regimes, namely, normal (23°C in open field) and elevated (6 ± 1°C higher compared to open field mean air temperature in polythene chamber) temperature, were created immediately after anthesis to investigate the response of wheat cultivars to heat stress. Elevated temperature cuts back the duration of grain filling by 5 days in BARI Gom 25 and BARI Gom 26 and 10 days in Pavon 76. Starch synthesis was also cut back by the same duration in respective cultivars under elevated temperature condition. Results indicate that failure of conversion of sugar to starch rather than limited supply of sugar under high temperature condition was responsible for shortening of grain filling duration in all wheat cultivars. However, the response of elevated temperature on grain starch and main stem grain dry matter was less profound in BARI Gom 25 and BARI Gom 26 compared to Pavon 76 indicating their better tolerance to elevated temperature.

Evaluation of Maize “Turda” Germplasm as Sources of Earliness in Breeding Programs

Evaluation of the early maize ( Zea mays L.) germplasm is important for the development of new inbred lines and commercial hybrids adapted to cooler regions. Choice of populations to use in improving elite maize hybrids is a critical decision in maize breeding programs. Our objectives were: I) to examine the variation for earliness in a set of 256 local populations, 56 synthetic populations and 504 inbred lines; II) to determine the performance and heterosis of this germplasm; III) to identify the genotypes (local populations, inbred lines) for the initiation of the primary cycle for directional selection for the studied characters. Seven synthetic populations and six inbred lines formed the base material of this genetic study. The seven synthetic populations and their topcrosses to four inbred lines: two flint inbred lines (TD 233 and CO 255) and two dent inbred lines (TC 184 and TC 209) and also a diallel type p(p-1) system with 30 single-cross hybrids and the six parental forms were evaluated at four environments in: two years 2009 and 2010 and two locations Turda and Targu- Mures. The highest values of additive effects for grain dry matter content were recorded at: Tu Syn Mara (ĝ n = +1.80), Tu SRR 5D (2I) (1) (ĝn = +0.62) and Tu Syn 1 (ĝn = +0.45). Therefore, Tu Syn Mara, Tu SRR 5D (2I)(1) and Tu Syn 1 produced hybrids with the most early maturity. The highest general combining ability (GCA) for dry matter accumulation in grains has registered the inbred lines TC209 (ĝ = +1.36) and TC208 (ĝ = +0.71).

Temporal and Spatial Profiling of Root Growth Revealed Novel Response of Maize Roots under Various Nitrogen Supplies in the Field

A challenge for Chinese agriculture is to limit the overapplication of nitrogen (N) without reducing grain yield. Roots take up N and participate in N assimilation, facilitating dry matter accumulation in grains. However, little is known about how the root system in soil profile responds to various N supplies. In the present study, N uptake, temporal and spatial distributions of maize roots, and soil mineral N (Nmin) were thoroughly studied under field conditions in three consecutive years. The results showed that in spite of transient stimulation of growth of early initiated nodal roots, N deficiency completely suppressed growth of the later-initiated nodal roots and accelerated root death, causing an early decrease in the total root length at the rapid vegetative growth stage of maize plants. Early N excess, deficiency, or delayed N topdressing reduced plant N content, resulting in a significant decrease in dry matter accumulation and grain yield. Notably, N overapplication led to N leaching that stimulated root growth in the 40–50 cm soil layer. It was concluded that the temporal and spatial growth patterns of maize roots were controlled by shoot growth and local soil Nmin, respectively. Improving N management involves not only controlling the total amount of chemical N fertilizer applied, but also synchronizing crop N demand and soil N supply by split N applications.

NEMA, a functional-structural model of nitrogen economy within wheat culms after flowering. II. Evaluation and sensitivity analysis.

Simulating nitrogen economy in crop plants requires formalizing the interactions between soil nitrogen availability, root nitrogen acquisition, distribution between vegetative organs and remobilization towards grains. This study evaluates and analyses the functional-structural and mechanistic model of nitrogen economy, NEMA (Nitrogen Economy Model within plant Architecture), developed for winter wheat (Triticum aestivum) after flowering. NEMA was calibrated for field plants under three nitrogen fertilization treatments at flowering. Model behaviour was investigated and sensitivity to parameter values was analysed. Nitrogen content of all photosynthetic organs and in particular nitrogen vertical distribution along the stem and remobilization patterns in response to fertilization were simulated accurately by the model, from Rubisco turnover modulated by light intercepted by the organ and a mobile nitrogen pool. This pool proved to be a reliable indicator of plant nitrogen status, allowing efficient regulation of nitrogen acquisition by roots, remobilization from vegetative organs and accumulation in grains in response to nitrogen treatments. In our simulations, root capacity to import carbon, rather than carbon availability, limited nitrogen acquisition and ultimately nitrogen accumulation in grains, while Rubisco turnover intensity mostly affected dry matter accumulation in grains. NEMA enabled interpretation of several key patterns usually observed in field conditions and the identification of plausible processes limiting for grain yield, protein content and root nitrogen acquisition that could be targets for plant breeding; however, further understanding requires more mechanistic formalization of carbon metabolism. Its strong physiological basis and its realistic behaviour support its use to gain insights into nitrogen economy after flowering.

Mapping Quantitative Trait Loci for Post‐Anthesis Dry Matter Accumulation in Wheat

AbstractPost‐anthesis photoassimilation is very important for wheat (Triticum aestivum L.) grain filling. The aim of the present study was to map quantitative trait loci (QTL) for post‐anthesis dry matter accumulation (DMA). A set of 120 doubled haploid (DH) lines, derived from winter wheat varieties Hanxuan 10 and Lumai 14, was grown under field conditions in two consecutive growing seasons during 2002–2004 in Beijing. Post‐anthesis DMA per culm and related traits, including flag leaf greenness (FLG) and flag leaf weight (FLW; dry weight per flag leaf) at flowering, and grain weight per ear (GWE) were investigated. All traits segregated continuously in the DH population in both trials. The DMA was significantly and positively correlated with GWE, with the correlation coefficients being 0.79 and 0.66 in the 2002–2003 and 2003–2004 growing seasons (both P < 0.01), suggesting the importance of DMA in grain filling. Further correlation analysis showed that FLW was more closely correlated with DMA and GWE than FLG in both growing seasons, indicating that FLW was more important than FLG in influencing DMA and GWE. In total, 30 QTLs for these four traits were mapped and distributed on 10 chromosomes. Phenotypic variations explained by an individual QTL were in the range 5.8%–21.3%, 5.9%–17.2%, 5.1%–18.1%, and 5.6%–16.2% for FLG, FLW, DMA, and GWE, respectively. Eight QTLs for DMA were detected, of which four (on chromosome arms 2AS, 4BL, 5AS, and 7AS) were linked with QTLs for GWE; two (on chromosome arms 5BL and 7BL) coincided with QTLs for FLW. These results may provide useful information for developing marker‐assisted selection for the improvement of DMA.(Managing editor: Wei Wang)

Grain sink strength may be related to the poor grain filling of indica-japonica rice (Oryza sativa) hybrids.

The physiological and biochemical factors contributing to poor grain filling of indica-japonica rice (Oryza sativa L.) hybrids were studied by analyzing the role of grain sink strength in dry matter accumulation of grains of two types of rice cultivars, Yayou 2 (an indica-japonica hybrid) and Yanjing 2 (a japonica cultivar). Carbon dioxide enrichment and plant hormone application were imposed at anthesis and the number of endosperm cells, dry matter accumulation and the activities of some sugar-metabolizing enzymes of grains were measured during grain filling. In Yayou 2, strong-potential grains (SPGs) accumulated dry weight much earlier than weak-potential grains (WPGs), but this difference was not obvious for Yanjing 2. Carbon dioxide enrichment imposed after heading significantly stimulated dry matter accumulation of WPGs of Yayou 2, but had little influence on WPGs of Yanjing 2 and SPGs of both cultivars. Leaf sheath dry matter decreased steadily in both cultivars during early stages of grain filling and accumulated during the later stages. Carbon dioxide enrichment increased leaf sheath dry matter. Dry matter accumulated by grains was linearly related to the increases in endosperm cell numbers and the activities of sucrose synthase (SS) and ADP-glucose pyrophosphorylase (AGPase) in SPGs and WPGs of both cultivars. Application of either 6-benzyladenine or abscisic acid had no significant influences on both endosperm cell number and grain dry matter accumulation. These results suggest that grain sink strength, determined by both cell numbers, SS and AGPase activities in the endosperm control the dry matter accumulation of grains.

A simple model for chickpea growth and yield

Chickpea ( Cicer arietinum L.) is a major crop in cool and cold semi-arid environments of Iran, where yield is limited by climatic factors, water availability and genotype. A robust crop model can assist in evaluation of biophysical limitations in crop yield. The objective of this study was, therefore, to develop a simple mechanistic model for chickpea to be used in assessing production limitations. The model simulates crop phenology, development of leaves as a function of temperature, accumulation of crop biomass as a function of intercepted radiation, dry matter accumulation of grains as a function of time and temperature, and soil water balance. Phenology, leaf growth and senescence and biomass production were made sensitive to soil water content. The model uses a daily time step and readily available weather and soil information. The model was tested using independent data from a range of Iran's environmental conditions. In most cases, simulated grain yield were similar to observed yield and ranged from 0.4 to 3.25 t/ha. The root mean square error was 0.24 t/ha. The agreement between simulated and observed grain yields showed the robustness of the model in predicting chickpea growth and yield for both irrigated and rainfed conditions. It was concluded that the model can be used in simulation studies of potential yield and production limitations.

Grain Filling Mechanisms in Spring Wheat. III. Effects of shadings on dry matter accumulation in grain and culm.

To determine the effects of assimilate shortage to grain filling mechanisms in spring wheat canopy (cv. Haruyutaka), we examined the accumulation and translocation of dry matter in grain, along with water soluble sugar content (WSC) and structural material in culm under shading conditions during grain filling phases. Shading treatments were conducted using 95% shading cloth from -2 to 7 days after anthesis (DAA) (initial shading), 7 to 14 DAA (early shading) and 14 to 21 DAA (late shading). These shadings prevented the wheat canopy from producing any assimilate. However rates of increase in grain dry weights for all the shadings were 50-60% of the control (no shading), while the WSC in culm was used for the grain growth. During the initial grain filling phase, the WSC in culm for the initial shading decreased (-15 mg pl-1day-1), whereas that for the control increased (20 mg pl-1day-1). The grain dry weight showed a high rate of increase (11 mg pl-1day-1) for the initial shading, being about 50% of the control (19 mg pl-1day-1). During the early phase, the WSC in culm for the early shading decreased (-15 mg pl-1day-1), although that for the control increased (12 mg pl-1day-1). The rate of grain weight increase for the early shading (24 mg pl-1dayl-1). During the late phase, the WSC in culm for the late shading decreased (-33 mg pl-1day-1) five times as much as the control (-7 mg pl-1day-1). The rate of grain weight increase for the late shading (34 mg pl-1day-1) was 60% of that for the control (55 mg pl-1day-1). Although the culm lengths at harvest were no different between the initial shading and the control, the dry weight of culm structural material for the initial shading was lower than that for the control. The difference between the cases in which the partitioning rate to grain did or did not increase is discussed herein.

The role of carbohydrate storage and redistribution in the source‐sink relations of wheat and barley during grain filling — a review

SUMMARYTwo types of source contribute photosynthate for grain filling in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.), current photosynthate transferred directly to the grain and photosynthate redistributed from reserve pools in vegetative tissues. Reserve pools provide the substrate needed to maintain transport and the supply of assimilate to grains during the dark period of the diurnal cycle and during the latter part of grain filling, when the photosynthetic apparatus is senescing and the rate of dry matter accumulation of grains exceeds the rate of dry matter accumulation of the total crop. In addition reserve pools provide a means by which the current rates of photosynthate production and of photosynthate use in grain filling are allowed to proceed (at least in part) independently from each other. There is evidence that all photosynthetic organs (leaves, glumes and exposed portion of the peduncle) contain one or more diurnal carbohydrate storage pools. Diurnal storage of sucrose seems to be much more important than the transient storage of starch. There is little evidence for fructan pools serving a role as a net source of carbon during the dark period of the diurnal cycle. However, fructan is the most important longer‐term reserve carbohydrate of vegetative tissues. Fructan accumulation occurs mainly in the extended internodes and leaf sheaths and usually terminates within three weeks following anthesis, after which fructan is gradually lost until grain maturity. The accumulation and loss of fructan are greatly influenced by environmental conditions and treatments that alter the longer‐term balance between photosynthate production by the plant and photosynthate use in grain filling. Observations are consistent with the view that fructan accumulation in expanded vegetative tissue is not competitive with grain filling, but the fructan pools accept surplus photosynthate during periods of low demand by grains and provide photosynthate during longer‐term deficits in current photosynthate production. Even under optimal conditions for photosynthesis it is likely that half or more of the photosynthate in mature grains is temporarily deposited in one or more reserve pools before being transferred to the grain. Neither the efficiency of reserve utilization in grain filling nor its potential variability in different genotypes and environments are known. Also, very little is known about the mechanisms that control the partitioning of photosynthate between the grain and reserve pools and the allocation to different types of reserve pools. Future progress in the understanding of photosynthesis‐yield relationships will likely depend to a great extent on improved knowledge of the controls that govern photosynthate deposition and redistribution in the different pools of reserve carbohydrate.

Germinability and seedling vigor of pearl millet seeds harvested at different stages of maturity

The effect of seed maturity on germinability and seedling vigor was studied in four cytoplasmic male sterile lines of pearl millet (Pennisetum glaucum (L.) R. Br.). The male sterile plants were crossed with pollen from respective maintainer lines, and developing seeds at different stages of maturity were harvested. Fresh weight of seeds increased gradually to a maximum in 28–35 days and then decreased. Maximum dry-matter accumulation in grain occurred at 28–35 days after pollination when the average moisture content was 22.7%. Seeds of some lines harvested at 10 days after pollination germinated, but the highest percentage germination was observed at 35 days in all lines. The maximum mean seedling vigor occurred at 35 days and coincided with the maximum dry weight of the seeds. Germplasm collectors can collect germinable seeds much earlier than the time of accumulation of maximum dry matter. However, for conservation, it is desirable to store mature seeds with maximum germination and vigor.

Effect of Defoliation During the Early Vegetative Phase and at Silking on Growth of Maize (Zea mays L.)

Two experiments were conducted in the glasshouse and in the field to evaluate the effect of leaf loss on development, dry matter accumulation and yield of maize. In the glasshouse, defoliation treatments were imposed on maize after 3 weeks of planting. Removing 2 or 3 leaves every 2 weeks affected plant height, days to tassel, root and shoot yield. The plant diameter and root: shoot ratio were not affected by defoliation. In the field experiment, six defoliation treatments were imposed 7 days after 50 per cent silking. Defoliation of all leaves was the most severe treatment on cob d. wt, dry matter accumulation in grains, weight of 100 test grains and yield. The effect of removing all leaves above the ear was not significantly different from that of removing all leaves below the ear. The effect of removing half of the leaves above the ear was not different from the control.