Seed-filling Period Research Articles

Comparison of soybean crop performance under tropical environment between tropical and temperate cultivars with adjusted growth duration

ABSTRACT Considerable variation among soybean genotypes has been observed in growth and yield adaptations to tropical environments. However, the response to daylength and, hence, different growth durations are confounding factors in most studies. In this study, we conducted field experiments in a tropical environment with daylength treatment to compare the crop performance of temperate and tropical cultivars with different daylength sensitivities in terms of biomass production, seed yield, and apparent seed quality. A tropical cultivar, ‘Tanggamus’, which has been highly productive in Indonesia, was grown for two years in a field at Bogor, Indonesia (lat. 6.5° S) with four cultivars from temperate regions. The proposed long-day treatment (LD) decreased the negative effects of short daylength in low-altitude areas on the vegetative growth and yield of soybean cultivars from temperate regions. With LD, the differences in the yield and above ground dry weight between temperate cultivars and ‘Tanggamus’ was less than without LD. However, the ratio of wrinkled seeds of temperate cultivars with LD was higher than that of ‘Tanggamus’. There were differences in the seed-filling rate and the growth rate of pod plus seed during latter half of the seed-filling period between them, indicating a higher ability in the supply of assimilates to seeds under high-temperature conditions during the seed-filling stage. These results suggest that temperate cultivars remain to be improved in biomass and seed production under environments with higher temperatures than the climate where they are cultivated, and that ‘Tanggamus’ will be worth utilizing in breeding programs.

Characterization of M8 Wheat Mutant Adaptability to Low Land

The wheat requirement in Indonesia is still fulfilled by import, which increases annually. To reduce the import dependence, Indonesia is required to elevate the domestic wheat production appropriate to the Indonesian agroclimatic condition by wheat plant breeding mutation. This study was aimed to characterize several mutant wheat commodities, that are adaptive to lowland condition. The experiment was arranged in a completely randomized block design with 16 observed-wheat genotypes (G). The wheat genotypes used were: 1) (G1) N1 200 2.4.B.6, 2) (G2) N 200 2.3.3, 3) (G3) N 200 2.5.2, (G4) N 350 3.6.2, (G5) N 350 3.7.1, (G6) N 300 3.6.1, (G7) N 350 3.1.3, (G8) N 250 3.7.1, (G9) M 200 1.7.1, (G10) S 300 7.9.1, (G11) S 300 2.1, (G12) D 200, and several comparative varieties, such as (G13) Guri-3 , (G14) Selayar , (G15) Nias , and (G16) Dewata . The results obtained that the lowland-adapted M8 wheat mutant with high productivity level was found in N 200 2.4.B.6 (2.75 t.ha -1 ), N 200 2.3.3 (2.69 t.ha -1 ), and D 350 3.6.2 (2.35 t.ha -1 ). Characters with the highest heritability level were number of tillers, number of productive tillers, seed weight per panicle, and production. Meanwhile, characters, that were correlated with production, were plant height, number of tillers, number of productive tillers, harvesting age, seed-filling period, number of spikelets per panicle, percentage of empty florets, number of seeds per panicle, and seed weight per panicle

Effect of high temperature during the late seed filling period on green stem disorder in soybean

ContextGreen stem disorder (GSD) in soybeans is a condition wherein delayed leaf and stem maturation at harvest negatively affects harvest efficiency and seed quality. Biotic and abiotic stresses promote GSD, which is mediated by sink limitations at the flowering and pod setting stages. Previous studies have suggested that high-temperature stress promotes GSD. However, the critical growth period and its mechanisms have not yet been elucidated. ObjectiveThe present study investigated the relationship between temperature and GSD severity in growth chambers and fields. MethodsThe study was conducted in two parts. First, the effects of high temperature on GSD (30/25 ℃, day/night) at different growth stages were analyzed in growth chambers. Second, field experiments were conducted to verify the relationship between temperature during the late seed-filling period and GSD severity. Three near-isogenic lines (NILs) with different combinations of maturation genes, E1, E2, and E3, were cultivated on three sowing dates (June, July, and August) for two years. ResultsHigh temperatures in the late seed-filling period significantly promoted GSD severity, whereas high temperatures in the early seed-filling period had no effect on GSD. Sink size did not decrease with high-temperature treatments. The field experiment in 2019 also revealed a positive correlation between GSD severity and mean temperature during the late seed-filling period, whereas mean temperature before the seed-filling period showed no correlation with GSD. Temperatures during the late seed-filling period accounted for GSD suppression in the late-maturation genotype and late sowing dates, whereas the early maturation genotype had an unknown mechanism to promote GSD. On the other hand, in the field experiment in 2020, ratio of source ability to sink size became lower than in 2019 because of higher solar radiation during sowing to R1 period increased sink size. As a result, in 2020, the effect of temperature relatively low compared to the effect of source-sink ratio. ConclusionThe findings indicate that high temperatures during the late seed-filling period promoted GSD. Sink limitations were not the cause of the phenomena. Annual variation of GSD occurrences could be explained by considering effects of both temperature and solar radiation in the specific growth stage. The late seed-filling period corresponds to autumn during the soybean cropping season. Therefore, the phenomena revealed in this study could be responsible for the GSD occurrences promoted by global warming in soybean fields. ImplicationsThis study facilitates selecting appropriate soybean cropping seasons and cultivars for each area to avoid GSD occurrence.

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

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

Impacts of mean climate and extreme climate indices on soybean yield and yield components in Northeast China

Soybean is an important oil crop in China, and the national focus of soybean production is in Northeast China. In order to achieve high-stable yield, it is crucial to acknowledge the impacts of mean climate and extreme climate indices on soybean yield and yield components. In this study, based on the weather data from 61 counties from 1981 to 2017 in Northeast China, we assessed the impacts of mean climate and extreme climate indices on soybean observed yield and simulated yield. Mean climate include effective growing degree days (GDD10), precipitation (Pre), and solar radiation (SR); extreme climate indices include the number of cool days during seed-filling period (C15), the number of cool days during 15 days before anthesis (C17), the number of hot days (H30), maximum amount of 5 Day accumulated precipitation (P5), and consecutive dry days (CDD)). We used the DSSAT-CROPGRO-Soybean model to identify the main yield components for soybean. The results showed that observed soybean yield reduced by 3.57% due to the collective changes in the eight study climate indices. Increases in GDD10, decreases in Pre, and decreases in SR caused a 3.96%, −3.89%, and − 0.48% change in soybean yield, respectively. Decreases in C15 and C17 led to a 5.36% increase in soybean yield; increases in H30, P5, and CDD caused a 5.75%, 0.30%, and 1.14% reduction in soybean yield, respectively. By comparing the response of observed and simulated soybean yield to climate indices (excluding P5) in the DSSAT-CROPGRO-Soybean model, we identified the key yield components for soybean as the number of pods and seed weight. The negative impacts on the number of pods and seed weight were mainly attributed to changes in Pre and H30 from anthesis to podding and during seed-filling period. Our results could be used to assist the local soybean community adapt to climate change.

Selection for yield shifted the proportion of oil and protein in favor of low-energy seed fractions in soybean

Owing to the high contents of oil and protein, soybean [Glycine max L. (Merr.)] seeds are energy-rich. Genetic improvement of soybean yield is linked to the dilution in seed protein; changes in low-energy compounds such as carbohydrates have received less attention. We tested the hypothesis that selection for yield in soybean has shifted seed composition in favor of low-energy compounds. We characterized the dynamics of three seed fractions (protein, oil, and residual) during seed filling in seven commercial soybean varieties released between 1980 and 2013 in a two-year field experiment. Genetic gain in yield was linked with reduced seed energy cost: seed protein concentration decreased by 0.06% yr−1, oil remained stable, and the residual fraction increased by 0.09% yr−1. Seed accumulation of the residual fraction revealed a shorter lag phase and a longer effective filling period for the modern relative to the older soybean varieties. Seed energetic requirement significantly decreased − 0.06% yr−1. Resource availability per seed during the seed-filling period was not limiting across all tested varieties. Further research is warranted on the biochemical nature of the residual fraction, and on the implications of seed composition for future breeding, soybean meal and end uses.

Safflower assimilate remobilization, yield, and oil content in response to nitrogen availability, sowing time, and genotype

In rainfed cropping systems, crops are typically subjected to terminal stresses, which diminish the assimilation process. Information regarding safflower (Carthamus tinctorius L.) dry matter dynamics during the seed-filling period and its association with yield-forming components is lacking. Field experiments over two years were conducted to assess the influence of nitrogen (N) fertilization levels (0, 100 and 200 kg ha−1), sowing time (autumn vs. spring) and genotype (two hybrids and an open-pollinated variety) on growth, assimilate remobilization, achene- and oil yield of safflower, and to identify early crop attributes as predictors of yield. Greater than 100 kg N ha-1 were required to optimize achene yield (> 4 Mg ha-1). On average, N promoted early growth and increased capitula and achenes per unit area compared with the non-fertilized control. The higher the availability of assimilates at the source, the greater their remobilization to sink (r = 0.823, P < 0.01), which was in turn associated with achene yield (r = 0.53, P < 0.05), provided that a critical sink size (number of achenes) had been established during flowering. Dry matter remobilization efficiency ranged between 29.5 % and 39.1 %. Under favorable conditions, hybrids exhibited higher achene- and oil yield than the variety. Oil yield was almost entirely (98 %) determined by achene yield. Autumn sowing increased the average achene yield (28 %) and oil production (20 %) compared with spring sowing. Harvest index (HI) ranged from 0.17 to 0.35 and was associated with achene yield (r = 0.703, P < 0.01). Achene yield could be predicted by measurements of dry matter at anthesis, while the estimation of biomass from plant height measurements was not applicable in safflower. Findings highlight the value of properly designed cropping systems for safflower production based on environmental variables and crop management practices, which can support high yields and improve N management.

Phytohormone dynamics impact fatty acid and oil accumulation during soybean seed maturation

AbstractFatty acid (FA) levels and profiles are vital for soybean oil quality, while cytokinins (CKs) and abscisic acid (ABA) are potent regulators of plant growth and development. Previous research suggested associations between FA biosynthesis and hormonal signalling networks; however, hormonal regulation of FA accumulation during soybean (Glycine max) seed maturation has never been measured. We analysed hormone and FA profiles obtained from HPLC-(ESI)-MS/MS and GC-FID screening during soybean seed maturation. A multilayered data processing approach, involving heat-maps, principal component analysis (PCA), correlation and multiregression models, suggested a strong relationship between hormone metabolism and FA/oil accumulation during seed maturation. Most strikingly, positive correlations were found between the levels of CK ribosides [transZeatin riboside (tZR), N6-isopentenyladenosine (iPR)] at the early stages of SM (R5-R6) and C18:0, C18:2 and oil content at the R8 stage. Moreover, multiple regression models revealed functional linkages between several CK derivatives and FA and oil content in mature seeds. To further test the significance of hormone regulation in FA metabolism, plants of two soybean accessions with contrasting hormone and FA profiles were sprayed with exogenous ABA and transZeatin (tZ) during the seed-filling period (R5-R6). Depending on the hormone type and concentration, these treatments distinctly modified biosynthesis of all tested FAs, except for C18:0. Most remarkably, tZ (50 nM) promoted production of C16:0, C18:1, C18:2, C18:3, and oil accumulation in maturing seeds. Overall, the results indicate impactful roles for ABA and CKs in FA accumulation during SM and represent a further step towards understanding FA biosynthesis, and potential improvements of soybean oil profiles.

Nitrogen dynamics during the seed-filling period in safflower under dryland Mediterranean conditions

Nitrogen dynamics during the seed-filling period in safflower under dryland Mediterranean conditions

Chemical composition and nutritional value of some varieties of soybean cultivated in Mongolia

Soybean has a lot of benefits for human nutrition, well-being and soil nutrition. Soybean seed contain higher concentration of protein and fat. The objective of this work was to evaluate the nutritional composition and mineral contents in soybean seeds of four different varieties of soybean for their future application as food products. The soybeans were cultivated in Mongolia. The moisture, protein, crude fat, reducing carbohydrate’s concentrations were determined by Kjeldahl, Soxhlet and Bertrand’s method in dried soybean seeds, and the calory of 100 g seed was calculated. The mineral concentration in the ash was determined by ICP-OES method. Among them, the Severnaya-4 variety contained the highest amount of protein, 31.5%, the Sibiryachka variety had the highest concentration of crude fat, 20.35%, and reducing sugar, 1.24%. Moreover, the Severnaya-4 and Sibiryachka soybean seeds had the highest mineral concentration. The lower concentration of protein of these four soybean varieties was probably due to the lower temperature during the seed-filling period in Mongolia. Sibiryachka and OAC vision had the highest amount of energy in 100 g raw seed than other two varieties. The Severnaya-4 and Sibiryachka soybean seeds could be better sources for protein, fat and minerals than the Nei dou-4 and OAC vision varieties.

Has yield plasticity already been exploited by soybean breeding programmes in Argentina?

This study focuses on the impact of genetic improvement of seed yield plasticity in soybean (Glycine max L.) in high-yielding environments (between 4000 kg ha-1 and 7000 kg ha-1) of Central Argentina. The association between seed yield and its plasticity was analysed with (i) a historical collection of 148 genotypes released to the market between 1980 and 2013 and (ii) 165 currently available commercial genotypes. The impact on seed yield of soybean breeding programmes in Argentina reveals higher genetic progress of the lowest (1.7% year-1) rather than the highest yielding genotypes (0.9% year-1). At the same time, seed yield plasticity has been exploited indirectly. Increased seed yield plasticity over time contributed to a reduction in genotypic seed yield variability (P<0.0001). Seed yield plasticity was related to seed yield in high-yielding environments (>5500 kg ha-1). Plastic genotypes showed a positive correlation with the length of the seed-filling period (r=0.5), suggesting that a longer seed-filling period could be required to maximize seed yield plasticity under high-yielding environments. To increase productivity, clarifying the value of plasticity will aid genotype selection for target environments, as well as the development of high-yielding cultivars specifically adapted to high-yielding conditions.

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 Site Specific Nitrogen Management on Seed Nitrogen—A Driving Factor of Winter Oilseed Rape (Brassica napus L.) Yield

It has been assumed that the management of both soil and fertilizer N in winter oilseed rape (WOSR) is crucial for N accumulation in seeds (Nse) and yield. This hypothesis was evaluated based on field experiments conducted in 2008/09, 2009/10, 2010/11 seasons, each year at two sites, differing in soil fertility, including indigenous N (Ni) supply. The experimental factors consisted of two N fertilizers: N and NS, and four Nf rates: 0, 80, 120, 160 kg ha−1. Yield, as governed by site × Nf rate interaction, responded linearly to Nse at harvest. The maximum Nse (Nsemax), as evaluated by N input (Nin = Ni + Nf) to WOSR at spring regrowth, varied from 95 to 153 kg ha−1, and determined 80% of yield variability. The basic reason of site diversity in Nsemax was Ni efficiency, ranging from 46% to 70%, respectively. The second cause of Nse variability was a shortage of N supply from + 9.5 soil to −8.8 kg ha−1 to the growing seeds during the seed filling period (SFP). This N pool supports the N concentration in seeds, resulting in both seed density and a seed weight increase, finally leading to a yield increase.

Sources of Nutrients for High-Yielding Winter Oilseed Rape (Brassica napus L.) during Post-Flowering Growth

Nutrient management by winter oilseed rape (WOSR) during the seed filling period (SFP) is crucial for seed density (SD), which subsequently determines seed yield (Y). This hypothesis was evaluated based on data from field experiments (2008-2010), with six treatments with sequentially added nutrients (0, NP, NPK, NPKMgS1(1/3 total MgS rate—spring applied), NPKMgS2 (total MgS rate autumn applied); NPKMgS3 (2/3-autumn, 1/3-spring). Nutrients accumulated in seeds were revealed as the most reliable WOSR trait, determining SD and Y. Yield was defined by the amounts of K and Mg in seeds. The amount nutrient remobilized from vegetative WOSR tissues was sufficient to cover the crop requirements during SFP for N, P, and Zn, but not for Ca, K, Mn, and Cu. The post-flowering K uptake resulted in PD, and SD increase, which subsequently resulted in a concomitant net uptake of Ca and Mg. The excessive accumulation of Ca, as well as Cu, and Mn in seeds due to a shortage of Mg, subsequently resulted in both SD and Y depression. The efficient exploitation of WOSR yielding potential as defined by SD, is possible, provided during the SFP reveals a net K and Mg uptake.

Do Soil Warming and Changes in Precipitation Patterns Affect Seed Yield and Seed Quality of Field-Grown Winter Oilseed Rape?

Increasing air and soil temperatures and changes in precipitation patterns as consequences of climate change will affect crop production in agricultural ecosystems. The combined effects of soil warming and altered precipitation on the productivity and product quality of oil crops are not yet well studied. Winter oilseed rape (OSR) (Brassica napus L., cv. Mercedes) was field-grown under elevated soil temperature (+2.5 °C), reduced precipitation amount (−25%), reduced precipitation frequency (−50%) both separately and in combination in order to investigate effects on crop development, seed yield, and seed quality. Soil warming accelerated crop development during early plant growth and during spring. At maturity, however, plants in all treatments were similar in quantitative (aboveground biomass, seed yield) and qualitative (protein and oil content, amino acids, fatty acids) parameters. We observed the long-term effects of the precipitation manipulation on leaf size, leaf senescence and biomass allocation. Seed yield was not affected by the altered climatic factors, perhaps due to adaptation of soil microorganisms to permanent soil warming and to relatively wet conditions during the seed-filling period. Overall, OSR performed well under moderate changes in soil temperature and precipitation patterns; thus, we observed stable seed yield without negative impacts on nutritive seed quality.

Plasticity of seed weight in winter and spring rapeseed is higher in a narrow but different window after flowering

Breeding heavier seeds while maintaining seed number has been proposed as an effective strategy to improve oil crop production. Recent studies assessing rapeseed source-sink (S-Sratio) reduction after flowering suggest a window in the early seed-filling period that can compensate, either partially or totally, for a decrease in the number of seeds. However, little evidence has been reported in relation to the key window for seed plasticity in rapeseed. Furthermore, such studies have only assessed spring rapeseed genotypes and there is a lack of information on winter rapeseed. This study aims to elucidate the occurrence of a narrow window when seed plasticity is greatest, which is hypothesized to occur during the early stages of seed filling after the beginning of flowering in both winter and spring rapeseed genotypes. To asses this hypothesis, two winter and two spring rapeseed hybrids were evaluated under three S-Sratio treatments in two experiments performed in field conditions in Valdivia, Chile. The winter hybrids Trust and Mercedes were assessed under different nitrogen levels, and the spring hybrids Lumen and Solar were assessed using two sowing dates. S-Sratio treatments in both rapeseed genotypes consisted of a control without S-Sratio manipulation, a reduced S-Sratio from the beginning of flowering [BBCH 61] to 15 days after flowering (DAF) and a reduced S-Sratio from 15 to 30 DAF. The S-Sratio was reduced by shading the crop with black nets to intercept 75 % of the incoming solar radiation. Shading treatments decreased seed yield relative to the control between 13 and 42 % for the winter genotypes and from 23 to 44 % for the spring genotypes. The negative effect of shading on seed number under both S-S reduction timings explains the seed yield reduction. Interestingly, different windows of time for seed weight plasticity were found in response to the lower S-Sratio for winter and spring genotypes (i.e., 15–30 and 0–15 DAF, respectively). In the winter-type genotypes, seed weight increased between 28 and 33 % under the 15–30 DAF shading treatment, while seed weight in spring-type genotypes increased from 15 to 39 % during the 0–15 DAF treatment. Seed weight change was almost negligible outside of the sensitivity window as this trait increased only 2% at 0–15 DAF in winter-type genotypes and 7% at 15–30 DAF in spring-type genotypes, across treatments. In parallel, the S-S reduction decreased seed number by 23.6 and 40 %, at the 0–15 and 15–30 DAF treatment, respectively. The study showed statistical differences for seed oil and protein concentration across treatments, but both quality traits remained highly stable to the S-S reduction and showed similar behavior in winter and spring rapeseed types. Seed oil concentration changed little while seed protein concentration was more sensitive to seed weight response. The findings of the present study suggest that seeds per silique and seed weight are determined by the plant assimilate S-Sratio; therefore, seed number and seed weight determinations overlap as has been demonstrated in other crops like wheat, barley, sorghum and sunflower.

High Temperatures During the Seed-Filling Period Decrease Seed Nitrogen Amount in Pea (Pisum sativum L.): Evidence for a Sink Limitation.

Higher temperatures induced by the on-going climate change are a major cause of yield reduction in legumes. Pea (Pisum sativum L.) is an important annual legume crop grown in temperate regions for its high seed nitrogen (N) concentration. In addition to yield, seed N amount at harvest is a crucial characteristic because pea seeds are a source of protein in animal and human nutrition. However, there is little knowledge on the impacts of high temperatures on plant N partitioning determining seed N amount. Therefore, this study investigates the response of seed dry matter and N fluxes at the whole-plant level (plant N uptake, partitioning in vegetative organs, remobilization, and accumulation in seeds) to a range of air temperature (from 18.4 to 33.2°C) during the seed-filling-period. As pea is a legume crop, plants relying on two different N nutrition pathways were grown in glasshouse: N2-fixing plants or NO3−-assimilating plants. Labeled nitrate (15NO3−) and intra-plant N budgets were used to quantify N fluxes. High temperatures decreased seed-filling duration (by 0.8 day per °C), seed dry-matter and N accumulation rates (respectively by 0.8 and 0.032 mg seed−1 day−1 per °C), and N remobilization from vegetative organs to seeds (by 0.053 mg seed−1 day−1 per °C). Plant N2-fixation decreased with temperatures, while plant NO3− assimilation increased. However, the additional plant N uptake in NO3−-assimilating plants was never allocated to seeds and a significant quantity of N was still available at maturity in vegetative organs, whatever the plant N nutrition pathway. Thus, we concluded that seed N accumulation under high temperatures is sink limited related to a shorter seed-filling duration and a reduced seed dry-matter accumulation rate. Consequently, sustaining seed sink demand and preserving photosynthetic capacity of stressed plants during the seed-filling period should be promising strategies to promote N allocation to seeds from vegetative parts and thus to maintain crop N production under exacerbated abiotic constraints in field due to the on-going climate change.

Oil quality in sea-level quinoa as determined by cultivar-specific responses to temperature and radiation conditions.

There is renewed interest in quinoa as a potential source of vegetable oils; however, there is no information about how environmental conditions affect its fatty acid composition, a critical indicator of its oil quality. The fatty acid concentrations of four cultivars adapted to temperate environments were compared at three sowing dates to evaluate the effect of environmental conditions during the seed-filling period on the variation in oil quality. The interaction between cultivar and sowing date was the main source of variation explaining the changes in the lipid content and fatty acid concentrations in quinoa. Most of the variation in the concentration of unsaturated fatty acids was attributed to the temperature and solar radiation during the seed-filling period; cultivar-specific responses to photo-thermal conditions were observed among the sea-level quinoa cultivars evaluated. The lipid content and concentration of fatty acids in quinoa are affected by sowing date. This effect is exerted through changes in temperature and solar radiation conditions. This managing practice can therefore be used to achieve quinoa oil with different qualities. © 2019 Society of Chemical Industry.

Evaluation of Soybean Greenness from Ground and Aerial Platforms and the Association with Leaf Nitrogen Concentration in Response to Drought

ABSTRACTEarly senescence has been noted for soybean (Glycine max [L.] Merr) exposed to drought. This research quantified the greenness of soybean canopy using digital image analysis throughout seedfilling for drought and well‐irrigated treatments. Five genotypes ranging from maturity groups (MGs) 2 to 5 were sown in field experiments for 3 yr. Leaf nitrogen (N) concentration decreased steadily throughout seedfill for all genotypes. The Dark Green Color Index (DGCI), which was determined from pictures taken from the ground, also decreased throughout the seedfill period for all genotypes, but did not indicate treatment differences between drought and well‐irrigated treatments. Aerial photographs taken from a height of 50 to 75 m also showed a progressive decline in DGCI values for all genotypes during seedfill, and also indicated that DGCI decreased faster and/or earlier in the season for the drought treatment than for the well‐irrigated treatment. The results demonstrated that aerial DGCI measurements have the promise to detect early senescence associated with drought, which may have applications in evaluating differences in sensitivity to drought among soybean genotypes.

Soybean Nitrogen Sources and Demand During the Seed‐Filling Period

Core Ideas Remobilization of N from vegetative organs fulfilled 59% of seed N, driven by plant biomass at R5.5.There was a trade‐off between N remobilization and N gain, connected to plant biomass and yield.Greater yields relied on both N remobilization and N gain during seed filling. Soybean [Glycine max (L.) Merr.] seed N demand not met by biological N fixation is fulfilled by N remobilization from vegetative plant organs and N uptake from soil sources during the seed‐filling period (SFP), herein termed N gain. The objectives of this study were to: (i) quantify the contribution of plant organs to N remobilization during the SFP, (ii) determine the association between N gain and N remobilization, and (iii) study the effect of seed yield in both N gain and N remobilization processes. Three field experiments were conducted in 2015 and 2016 in Kansas. Three soybean genotypes: (i) non‐Roundup Ready (RR), released in 1997; (ii) RR‐1, released in 2009; and (iii) RR‐2, released in 2014 were tested under three N rates: (i) control without N application (zero‐N); (ii) 56 kg N ha−1 applied at R3 stage (late N); and (iii) 670 kg N ha−1 (full N; three applications of 223 kg N ha−1) applied at planting, R1, and R3 stages. The late‐N and full‐N rates increased yields by 9% (256 kg ha−1) relative to the zero N. Neither genotypes nor N rates affected N gain nor N remobilization. Nitrogen remobilization accounted for 59% of seed N demand at maturity, mainly driven by biomass at R5.5, with the leaf organ as the main contributor (52%) of the total remobilized N. Nitrogen remobilization was negatively related to N gain, and increases in N gain were linked to increases in biomass and yield.