Seed Filling Research Articles

Temporal and spatial transcriptional regulation of phytohormone metabolism during seed development in barley (Hordeum vulgare L.).

Plant hormones play important roles in seed development; however, transcriptional regulation of their metabolism and levels of the respective bioactive forms during barley seed development is poorly understood. To this end, this study performed a comprehensive analysis of changes in the expression patterns phytohormone metabolism genes and levels of the respective bioactive forms in the embryo and endosperm tissues. Our study showed the presence of elevated levels of abscisic acid (ABA), bioactive forms of gibberellins (GAs), jasmonate (JA) and cytokinins (CKs), auxin and salicylic acid (SA) in the endosperm and embryo tissues at early stage of seed filling (SF). The levels of all hormones in both tissues, except that of ABA, decreased to low levels during SF. In contrast, embryonic ABA level increased during SF and peaked at physiological maturity (PM) while the endospermic ABA was maintained at a similar level observed during SF. Although its level decreased high amount of ABA was still present in the embryo during post-PM. We detected low levels of ABA in the endosperm and all the other hormones in both tissues during post-PM phase except the relatively higher levels of jasmonoyl-isoleucine and SA detected at late stage of post-PM. Our data also showed that spatiotemporal changes in the levels of plant hormones during barley seed development are mediated by the expression of specific genes involved in their respective metabolic pathways. These results indicate that seed development in barley is mediated by spatiotemporal modulation in the metabolism and levels of plant hormones.

Effects of Heat Stress during Seed Filling Stage on Brassica napus Seed Oil Accumulation and Chlorophyll Fluorescence Characteristics

As global temperature rise, the threat of heat stress to rapeseed production is becoming more obvious. Exploring the response characteristics of two important biological pathways, oil accumulation and photosynthesis, to heat stress during B. napus seed filling is helpful in the genetic improvement of heat-tolerant rapeseed. The effects of heat stress on seed oil accumulation and chlorophyll fluorescence characteristics of 29 B. napus germplasms with different oil content and environmental sensitivity, including 6 rapeseed varieties which exhibited environment-sensitive/insensitive and with high, medium or low oil content, were tested by whole plant heat stress or the in vitro silique culture system. Both assay exhibited similar trend on oil content of the rapeseed germplasms. The heat effect on the chlorophyll fluorescence kinetic parameters Fv/Fm, ETR and Y(II) were also consistent. Heat stress significantly decreased oil content, although there was abundant genetic variation on heat tolerance among the genotypes. Correlation analysis showed that the decrease rate of Fv/Fm of silique heat-stressed B. napus developing seed was positive correlative to the decrease rate of mature seed oil content of the whole plant heat-stressed rapeseed (R = 0.9214, P-value < 0.01). Overall, the results indicated that heat stress inhibited oil accumulation and photosynthesis in B. napus developing seed. The decrease rate of chlorophyll fluorescence parameter Fv/Fm of heat-stressed developing seed could be used as the index of heat tolerant rapeseed identification. Further, two heat insensitive rapeseed varieties with high oil content were identified.

Source-Sink Manipulation and Its Impacts on Canola Seed Filling Period

Source-Sink Manipulation and Its Impacts on Canola Seed Filling Period

Optimization and Experiment of a Disturbance-Assisted Seed Filling High-Speed Vacuum Seed-Metering Device Based on DEM-CFD

In disturbance-assisted seed filling vacuum seed-metering devices, the suction hole causes difficulty in quickly and stably sucking seeds when used for high-speed seeding and the large working negative pressure demand is used. To address this difficulty, this study’s authors designed a seed disk hole with a variable cross-section structure, and the groove depth, which has the function of assisting seed filling, was optimized. Using the combined method of Fluent numerical analysis and an orthogonal experiment, the influence of the shape, inlet diameter, and length of the seed disk hole on the pressure difference of the seed disk hole was analyzed. The working process of the vacuum seed meter was simulated and analyzed by the Discrete Element Method and Computational Fluid Dynamics coupling method. It was found that with the increase of the diameter of the seed disk hole, the pressure difference decreased, and the length of the seed disk hole had little effect on the pressure difference. The best diameter of the seed disk hole was 5.4 mm, and the length was 5 mm. It was found that the pressurization effect of the arc-shaped seed disk hole is better. With the increase of groove depth, the leakage rate shows a trend of first decreasing and then increasing, which was determined to be 1.5 mm. The verification experiment proved that the working performance of the optimized seed metering device is better than that of the original one. The results show that when the working negative pressure was 4 kPa and the working speeds were 8~14 km·h−1, the qualified rate was not less than 95.0%, and the seed filling performance was relatively stable. The optimized vacuum seed metering device can be applied to high-speed seeders, while ensuring the requirements of high-speed sowing operations.

Genetic Relationships Among Physiological Processes, Phenology, and Grain Yield Offer an Insight Into the Development of New Cultivars in Soybean (Glycine max L. Merr).

Soybean grain yield has steadily increased during the last century because of enhanced cultivars and better agronomic practices. Increases in the total biomass, shorter cultivars, late maturity, and extended seed-filling period are frequently reported as main contributors for better soybean performance. However, there are still processes associated with crop physiology to be improved. From the theoretical standpoint, yield is the product of efficiency of light interception (Ei), radiation use efficiency (RUE), and harvest index (HI). The relative contribution of these three parameters on the final grain yield (GY), their interrelation with other phenological–physiological traits, and their environmental stability have not been well established for soybean. In this study, we determined the additive–genetic relationship among 14 physiological and phenological traits including photosynthesis (A) and intrinsic water use efficiency (iWUE) in a panel of 383 soybean recombinant inbred lines (RILs) through direct (path analyses) and indirect learning methods [least absolute shrinkage and selection operator (LASSO) algorithm]. We evaluated the stability of Ei, RUE, and HI through the slope from the Finley and Wilkinson joint regression and the genetic correlation between traits evaluated in different environments. Results indicate that both supervised and unsupervised methods effectively establish the main relationships underlying changes in Ei, RUE, HI, and GY. Variations in the average growth rate of canopy coverage for the first 40 days after planting (AGR40) explain most of the changes in Ei. RUE is primarily influenced by phenological traits of reproductive length (RL) and seed-filling (SFL) as well as iWUE, light extinction coefficient (K), and A. HI showed a strong relationship with A, AGR40, SFL, and RL. According to the path analysis, an increase in one standard unit of HI promotes changes in 0.5 standard units of GY, while changes in the same standard unit of RUE and Ei produce increases on GY of 0.20 and 0.19 standard units, respectively. RUE, Ei, and HI exhibited better environmental stability than GY, although changes associated with year and location showed a moderate effect in Ei and RUE, respectively. This study brings insight into a group of traits involving A, iWUE, and RL to be prioritized during the breeding process for high-yielding cultivars.

Effect of Late Season Management Practices on Soybean Seed Filling and Yield

Effect of Late Season Management Practices on Soybean Seed Filling and Yield

Potassium Application Affects Key Enzyme Activities of Sucrose Metabolism during Seed Filling in Vegetable Soybean

Pot experiments were conducted in 2014 and 2015 with two vegetable soybean [Glycine max (L.) Merr.] cultivars (‘Zhongkemaodou 1’ and ‘121’) under normal rates of nitrogen and phosphorus application with three potassium (K) fertilization treatments: no K application (K0), 120 kg K2SO4 ha−1 at seeding (K1), and 120 kg K2SO4 ha−1 at seeding + 1% K2SO4 foliar application at flowering (K2). Potassium application significantly increased seed sucrose concentration, and the highest seed sucrose concentrations were uniformly observed in the treatment of foliar K application after flowering. At 7 wk after flowering, the highest stage of seed sucrose concentration, K1 and K2 treatments increased sucrose concentration by 19.8 to 44% and 29.1 to 86.4% for Zhongkemaodou 1, and 7.2 to 42.1% and 26.2 to 63.8% for 121, respectively. Changes of net activities of sucrose‐metabolizing enzymes in seed paralleled the trend of sucrose accumulation. Potassium application increased the activities of sucrose phosphate synthase and sucrose synthase with increased sucrose synthesis but reduced the activity of sucrose synthase with increased sucrose decomposition. Potassium application also reduced the activities of acid invertase and neutral invertase, especially around seed ripening. Potassium fertilization enhanced seed net activities of key enzymes in sucrose metabolism and subsequently induced the increase in sucrose concentration of vegetable soybean.

DEHYDRINS PATTERNS IN COMMON BEAN EXPOSED TO DROUGHT AND WATERED CONDITIONS

Drought is a major constraint for common bean (Phaseolus vulgaris L.) production in México. Dehydrins are constitutive or stress-induced proteins related with a protective role of membranes and macromolecules against denaturation, thus preventing loss of their function. In this work, seed production and patterns of dehydrins accumulation in leaves and pods were evaluated in common bean cv. ‘Otomí’ subjected to drought, as compared with well-irrigated plants. Drought applied at pod formation and seed filling (SF) reduced yield up to 57 %. An antibody against a consensus sequence present in most dehydrins allowed for dehydrin identification. Two dehydrins of 82 and 73 kDA turned up both in leaves and pods throughout all the evaluated conditions. Presumably, both dehydrins are constitutive in the ‘Otomí’ cultivar. These dehydrins showed higher expression than controls in leaves after 6 d of drought at seedling and SF stages, and in pods 6 d after drought had started at SF. Increased expression might provide better protection during early stages of seedling and seed development. Increments on 63, 36 and 22 kDa dehydrin expression in pods at late SF might coincide with plant developmental programs, which prepare seed for desiccation. Dehydrins of 158, 54, 46, and 41 kDa were detected in pods 10 d after floral opening as a transient response to drought stress in SF. These results indicate dehydrins are relevant during plant development, as well as during drought stress.

P-Solubilizing Bacteria and Phosphorus Fertilizer Applications to Sunflower Improves Seed Set, Seed Filling Efficiency and Concentration of Macro-and

P-Solubilizing Bacteria and Phosphorus Fertilizer Applications to Sunflower Improves Seed Set, Seed Filling Efficiency and Concentration of Macro-and

Water Deficit Effect on the Relationship between Temperature during the Seed Fill Period and Soybean Seed Oil and Protein Concentrations

Since most soybean [Glycine max (L.) Merr.] seed is processed into meal and oil, there is a growing concern about environmental effects on soybean seed composition. The aim of this work was to investigate how water deficit affects the well‐known relationship of soybean seed oil and protein concentrations with temperature and, alternatively, with solar radiation during seed fill. We analyzed oil and protein data from multienvironment trials in Argentina (latitude 29° to 38° S). Multiple linear regressions were used to test the effect of water deficit on the relationship between oil, protein, and oil + protein and temperature. The functions relating oil and protein concentrations with average daily mean temperature during seed fill (TmR5R7) changed with water deficit. When precipitation minus potential evapotranspiration during the reproductive period (pp‐PETR1R7) was lower than 70 mm, oil increased linearly with increasing TmR5R7 and with rising water deficit. Meanwhile, protein increased linearly with TmR5R7 but decreased linearly with water deficit. Oil + protein concentration held a linear relationship with TmR5R7 even under water deficit. Cumulative solar radiation during seed fill predicts seed quality but shows lower significance than TmR5R7 This research demonstrates that a water‐stress indicator (pp‐PETR1R7) should be considered in rainfed crops because it affects the well‐known relationship of soybean seed oil and protein concentrations with temperature.

Response of Soybean Yield to Daytime Temperature Change during Seed Filling: A Long-Term Field Study in Northeast China

Daytime temperature during seed filling is a crucial determinant of grain yield in pulse crops. Although there is much research about the effect of daytime temperature during seed filling on soybean yield in temperature-controlled chambers, the effect in the field has been little explored. Long-term manipulative field experiments are important tools to provide accurate information for revealing the impacts of climate change on crop yields. Using the field records of a long-term fertilization experiment conducted in Northeast China, we analyzed the response of soybean yields to mean daily maximum temperature during seed filling over the period 1987−2007. The results showed that there was a clear positive response of soybean yields to increased mean daily maximum temperature during seed filling ranged from 20 to 24ºC. When compared with the average soybean yields over the last two decades, grain yields increased by 6−10% for each 1ºC increase in mean daily maximum temperature during seed filling and more than 22% of yield trends can be explained. These findings provide a direct evidence for the response of soybean yield to climate change in the field study.

Transcriptional Regulation of Storage Protein Synthesis During Dicotyledon Seed Filling

Seeds represent a major source of nutrients for human and animal livestock diets. The nutritive value of seeds is largely due to storage products which accumulate during a key phase of seed development, seed filling. In recent years, our understanding of the mechanisms regulating seed filling has advanced significantly due to the diversity of experimental approaches used. This review summarizes recent findings related to transcription factors that regulate seed storage protein accumulation. A framework for the regulation of storage protein synthesis is established which incorporates the events before, during and after seed storage protein synthesis. The transcriptional control of storage protein synthesis is accompanied by physiological and environmental controls, notably through the action of plant hormones and other intermediary metabolites. Finally, recent post-genomics analyses on different model plants have established the existence of a conserved seed filling process involving the master regulators (LEC1, LEC2, ABI3 and FUS3) but also revealed certain differences in fine regulation between plant families.

Dehydrin‐Like Proteins in Soybean Seeds in Response to Drought Stress during Seed Filling

There is no information on accumulation of dehydrin proteins during seed development and maturation of soybean [Glycine max (L.) Merr.] in response to drought stress. Our objective was to study accumulation of dehydrin‐like proteins in developing soybean seeds in response to drought stress. A greenhouse experiment and a field experiment were conducted. In the greenhouse experiment, three treatments were imposed on soybean plants after beginning of linear seed filling (R5): well‐watered (WW), gradual stress (GS) imposed before severe stress, and sudden severe stress (SS). In the field treatments were irrigation (I) and nonirrigation (NI) (rainfed) conditions imposed from R5 to R8 (mature seeds). Greenhouse results indicated dehydrin‐like proteins (28 and 32 kDa) were detected 18 d after R5 (R5.8) in developing seeds from drought‐stressed plants but not in seeds from the well‐watered plants. In the mature seeds, dehydrin‐like proteins (28, 32, and 34 kDa) were detected in seeds from drought‐stressed plants as well as the well‐watered plants. In the field, dehydrin‐like proteins accumulated similarly under irrigation and nonirrigation conditions, with the first detection for dehydrins (28 and 32 kDa) at 22 d after R5 (R6). Accumulation of dehydrin‐like proteins was maximal in seeds harvested at 43 d after R5 (seed physiological maturity).

Large Scale Identification and Quantitative Profiling of Phosphoproteins Expressed during Seed Filling in Oilseed Rape

Seed filling is a dynamic, temporally regulated phase of seed development that determines the composition of storage reserves in mature seeds. Although the metabolic pathways responsible for storage reserve synthesis such as carbohydrates, oils, and proteins are known, little is known about their regulation. Protein phosphorylation is a ubiquitous form of regulation that influences many aspects of dynamic cellular behavior in plant biology. Here a systematic study has been conducted on five sequential stages (2, 3, 4, 5, and 6 weeks after flowering) of seed development in oilseed rape (Brassica napus L. Reston) to survey the presence and dynamics of phosphoproteins. High resolution two-dimensional gel electrophoresis in combination with a phosphoprotein-specific Pro-Q Diamond phosphoprotein fluorescence stain revealed approximately 300 phosphoprotein spots. Of these, quantitative expression profiles for 234 high quality spots were established, and hierarchical cluster analyses revealed the occurrence of six principal expression trends during seed filling. The identity of 103 spots was determined using LC-MS/MS. The identified spots represented 70 non-redundant phosphoproteins belonging to 10 major functional categories including energy, metabolism, protein destination, and signal transduction. Furthermore phosphorylation within 16 non-redundant phosphoproteins was verified by mapping the phosphorylation sites by LC-MS/MS. Although one of these sites was postulated previously, the remaining sites have not yet been reported in plants. Phosphoprotein data were assembled into a web database. Together this study provides evidence for the presence of a large number of functionally diverse phosphoproteins, including global regulatory factors like 14-3-3 proteins, within developing B. napus seed.

Air Temperature During Seed Filling and Soybean Seed Germination and Vigor

High temperature stress during seed filling in controlled environments reduces soybean [Glycine max (L.) Merrill] seed germination and vigor, but the effect of high temperature in the field has not been determined. Seeds of two soybean cultivars (Hutcheson, maturity group [MG] V, and DP4690, MG IV) were produced in the field in Kentucky, Mississippi, Arkansas, and Texas in 2000 to 2002. Air temperature during seed filling was monitored and brown (mature) pods were harvested, hand threshed, and all shriveled and abnormal seeds were removed before determining standard germination and vigor (accelerated‐aging germination). Mean maximum temperatures during seed filling (growth stage R5 to R7) ranged from 24.0 (Kentucky) to 37.6°C (Texas). When seed lots infected with Phomopsis longicolla (Hobbs) were removed from the analysis, standard germination and accelerated‐aging germination (AA) decreased as mean maximum temperature during seed filling increased, but the decrease was significant (P = 0.05) only for Hutcheson. Standard germination of Hutcheson declined linearly (r 2 = 0.49) from near 100% at 24°C to 85% at 36°C, while the decrease in AA was curvilinear (R 2 = 0.86) and germination reached 11% at 36°C. Seeds of Hutcheson were more sensitive to high temperature than seeds of DP4690 and seed vigor (AA) was much more sensitive to high‐temperature stress than was standard germination. Our findings support the results of experiments in controlled environments by demonstrating that high temperature during seed filling in the field, without seed infection with P. longicolla or physical injury, reduced soybean seed germination and vigor.

Soybean Cultivar Differences on Light Interception and Leaf Area Index during Seed Filling

Light interception and leaf area criteria to maintain optimum soybean [Glycine max (L.) Merr.] yield during the last half of the seed filling period have been developed since this is the period of most frequent infestations by defoliating insects in the southeastern USA. Because these criteria were developed for only one cultivar, Centennial, they would have greater applicability if shown to be applicable across a range of cultivars. The objective of this research was to determine if these previous criteria are applicable across a range of commercial soybean cultivars. The study was conducted at the Ben Hur Research Farm near Baton Rouge, LA (30°N lat), on a Commerce silt loam soil (fine‐silty, mixed, nonacid, thermic, Aeric, Fluvaquent). Planting dates were 3 June 1997 and 30 June 1998. The experimental treatments consisted of a factorial combination of 10 soybean cultivars and three leaf defoliation treatments: a nondefoliated control, partial defoliation at the temporal midpoint of seed filling, and total defoliation at the temporal three‐fourths point of seed filling. Leaf area index (LAI) and canopy light interception (LI) were measured after defoliation treatments. Grain yield was determined at maturity by machine harvest. Partial defoliation at mid–seed filling significantly (P &lt; 0.05) reduced LAI, LI, and yield in 8 out of 10 cultivars in at least 1 yr of the study. Total defoliation at the three‐fourths point of seed filling also reduced yields for almost every cultivar–year treatment combination. Our results tended to support the original criteria related to LI and leaf area criteria for maintenance of optimal yield.

Soybean Cultivar Differences on Light Interception and Leaf Area Index during Seed Filling

Light interception and leaf area criteria to maintain optimum soybean [Glycine max (L.) Merr.] yield during the last half of the seed filling period have been developed since this is the period of most frequent infestations by defoliating insects in the southeastern USA. Because these criteria were developed for only one cultivar, Centennial, they would have greater applicability if shown to be applicable across a range of cultivars. The objective of this research was to determine if these previous criteria are applicable across a range of commercial soybean cultivars. The study was conducted at the Ben Hur Research Farm near Baton Rouge, LA (30°N lat), on a Commerce silt loam soil (fine-silty, mixed, nonacid, thermic, Aeric, Fluvaquent). Planting dates were 3 June 1997 and 30 June 1998. The experimental treatments consisted of a factorial combination of 10 soybean cultivars and three leaf defoliation treatments: a nondefoliated control, partial defoliation at the temporal midpoint of seed filling, and total defoliation at the temporal three-fourths point of seed filling. Leaf area index (LAI) and canopy light interception (LI) were measured after defoliation treatments. Grain yield was determined at maturity by machine harvest. Partial defoliation at mid–seed filling significantly (P < 0.05) reduced LAI, LI, and yield in 8 out of 10 cultivars in at least 1 yr of the study. Total defoliation at the three-fourths point of seed filling also reduced yields for almost every cultivar–year treatment combination. Our results tended to support the original criteria related to LI and leaf area criteria for maintenance of optimal yield.

Short Periods of Water Stress during Seed Filling, Leaf Senescence, and Yield of Soybean

The effects of short periods of water stress during seed‐filling on leaf senescence, seed‐fill duration, and yield of soybean [Glycine max (L.) Merrill] are not well understood. Short stress periods were investigated in two greenhouse experiments with cultivar Elgin 87 grown in soil‐filled pots. All pots received adequate water until the beginning of growth stage R6 when a continuous water‐stress treatment (pots received 40% of the water needed to bring controls to pot capacity) was initiated and maintained until maturity. Water stress was relieved in other pots (watered as the control) after 5 or 13 d in Exp. 1 and 3 or 6 d in Exp. 2. Each treatment was replicated six to eight times in a completely randomized design. The carbon exchange rate was rapidly reduced by continuous water stress resulting in earlier maturity, significantly lower yield (39%), and smaller seeds (25–33%). The carbon exchange rate rapidly increased to near control levels in the early stress‐relief treatment, but it was always less than the control for the rest of seed filling. These plants matured sooner and produced significantly lower yields (10–23%) and smaller seeds (9–17%) than control plants. Late stress relief also reduced yield and seed size relative to the control. Yield and seed size of both stress relief treatments, however, were greater than the continuous stress treatment. Water stress‐induced acceleration of senescence could not be stopped by eliminating the stress after a short period. Short periods of water stress during seed filling may, therefore, have larger than expected effects on yield.

Intercepted Solar Radiation during Seed Filling Determines Sunflower Weight per Seed and Oil Concentration

A reduction in intercepted photosynthetically active radiation (PAR) during a short period of seed filling could affect weight per seed and oil concentration in sunflower (Helianthus annuus L.) depending when the reduction occurs. The main objectives of this work were (i) to determine the period of time during which intercepted PAR most influences final weight per seed and oil concentration, and (ii) to establish and validate relationships between intercepted PAR during such a period and oil yield components. Intercepted PAR was modified by shading (0, 50, or 80%) field grown crops during different periods of seed filling. Data from published and unpublished field experiments, in which intercepted PAR per plant was changed during the entire seed filling period by shading, thinning to reduce plant population, or both, were also used. All experiments were performed under adequate water and nutrient conditions. A reduction in intercepted PAR during 7 to 10 d of seed filling affected weight per seed and oil concentration. The developmental interval during which final weight per seed and oil concentration were best accounted for by accumulated intercepted PAR (r2 &gt; 0.805) began at 250°C d and ended at 450°C days after flowering (DAF). The established relationships were validated with independent data. The relationships obtained in this work help to explain the effects of environment and crop management (sowing date, location, year) on oil yield variation.

Intercepted Solar Radiation during Seed Filling Determines Sunflower Weight per Seed and Oil Concentration

A reduction in intercepted photosynthetically active radiation (PAR) during a short period of seed filling could affect weight per seed and oil concentration in sunflower (Helianthus annuus L.) depending when the reduction occurs. The main objectives of this work were (i) to determine the period of time during which intercepted PAR most influences final weight per seed and oil concentration, and (ii) to establish and validate relationships between intercepted PAR during such a period and oil yield components. Intercepted PAR was modified by shading (0, 50, or 80%) field grown crops during different periods of seed filling. Data from published and unpublished field experiments, in which intercepted PAR per plant was changed during the entire seed filling period by shading, thinning to reduce plant population, or both, were also used. All experiments were performed under adequate water and nutrient conditions. A reduction in intercepted PAR during 7 to 10 d of seed filling affected weight per seed and oil concentration. The developmental interval during which final weight per seed and oil concentration were best accounted for by accumulated intercepted PAR (r2 > 0.805) began at 250°C d and ended at 450°C days after flowering (DAF). The established relationships were validated with independent data. The relationships obtained in this work help to explain the effects of environment and crop management (sowing date, location, year) on oil yield variation.