High Seed Protein Content Research Articles

Effects of defoliation on seed protein concentration in normal and high protein lines of soybean

Two high (NC106, NC111) and two normal (NC103, NC107) seed protein concentration lines, derived from two different recurrent selection populations of soybean (Glycine max L. Merr.) were subjected to partial defoliation at beginning seed fill (R5) under outdoor pot culture and field conditions. The aim of this study was to test the hypothesis that capacity to store N in vegetative organs and/or to mobilize that N to reproductive organs is associated with the high seed protein concentration trait. Symbiotic N2 fixation was the sole source of N in the pot experiment and the major source of N (met > 50% of the N requirement) in the low N soil used in the field experiment. Seed protein concentration and seed yield at maturity in both experiments and N accumulation and mobilization between R5 and maturity in the pot experiment were measured. The four genotypes did not differ significantly with respect to the amount of N accumulated before beginning seed fill (R5). Removal of up to two leaflets per trifoliolate leaf at R5 significantly decreased the seed protein concentration of NC107/111 but had no effect on this trait in NC103/106. Defoliation treatments significantly decreased seed yield, whole plant N accumulation (N2-fixation) during reproductive growth and vegetative N mobilization of all genotypes. Differences in harvest indices between the high and low protein lines accounted for approximately 35% of the differences in protein concentration. The two normal protein lines mobilized more vegetative N to the seed (average. 5.26 g plant−1) than the two high protein lines (average. 4.28 g plant−1). The two high seed protein lines (NC106, NC111) exhibited significantly different relative dependencies of reproductive N accumulation on vegetative N mobilization, 45% vs. 29%, in the control treatment. Whereas, NC103 with normal and NC106 with high seed protein concentration exhibited similar relative dependencies of reproductive N accumulation on vegetative N mobilization, (47% vs. 45%). Collectively, these results indicate that N stored in shoot organs before R5 and greater absolute and relative contribution of vegetative N mobilization to the reproductive N requirement are not responsible for the high seed protein concentration trait.

Effect of level and timing of moisture stress on soybean yield, protein, and oil responses

Field studies were conducted in 1984 and 1985 using small plots (non-weighing lysimeters) of 1 m 2 to determine the effect of four levels (L) and three times (T) of soil moisture stress treatments on yield and quality of Maple Amber soybean [ Glycine max (L.) Merr.]. The study incorporated the most probable combinations of these moisture stress treatments. Thousand-seed weight was inversely related to L ( n 2 = 0.98). The L × T effect on seed yield was significant ( P = 0.01). Seed yield decreased continuously from 1863 to 847 kg/ha (mean of 2 years) with increasing moisture stress levels when irrigation was applied at each prescribed L, regardless of growth stage ( r 2 = 0.93). In this case, however, irrigation produced no appreciable yield advantage above that obtained at 33% moisture stress level, or greater, when moisture stress at growth stage R2 was induced. In the latter case, a linear relationship of yield with moisture stress ( r 2 = 0.96) was obtained. Constant but low yields were maintained across the moisture stress range by withholding irrigation at R5, even though adequate water was applied to plants up to the induced stress. Protein was mainly affected by L ( P = 0.01). A curvilinear relationship of protein with moisture stress ( r 2 = 0.99) demonstrated that the highest seed protein content is associated with a well-watered condition maintained by frequent irrigation. The oil, in contrast, was affected by T ( P = 0.01). The highest yields together with the highest seed protein could be achieved under well-watered conditions. Under a high water deficit, in contrast, only moderate protein content was obtained, but yield was reduced significantly.

Modified Seed Maturation Rates and Seed Yield Potentials in Soybean

Seed embryos of soybean [Glycine max (L.) Men‐.] genotypes can have different levels of specific dry matter accumulation rate (SDMAR) and specific seed density (SSD) under greenhouse growing conditions, but the relevance of these measures for field‐grown plants is not known. The objectives of this research were to interrelate these measures as they reflect characteristics of the developing soybean seed and to determine their association with seed‐yield potential. As the seed matured, SSD increased ⊄0.01 g cm−3 d−1. Differences in this rate of change were positively associated with SDMAR. Genotypes selected for increased, as compared with decreased, seed‐filling duration had lower SDMAR and lower rate of change in SSD (decreased seed maturation rate) and greater seed yield under favorable field conditions. However, the yield advantage was lost under environments having drought stress during the reproductive period. Selections for high seed protein content exhibited an apparent increased seed‐maturation rate and a reduced seed yield. Divergent selection for SSD produced major shifts in SSD at the 55% seed‐filling stage. In contrast, the modified reproductive period selections and the seed protein selections had only secondary differences for SSD at that seed‐filling stage, indicating that the low SSD selections initiated delayed seed maturation at an earlier stage of seed development. While the low SSD selections had the reduced seed‐maturation rates, they did not express the expected yield advantage. Under drought stress, they exhibited lower seed number and seed yield than the modified reproductive period and high SSD selections. The stage of maturity for initiating delayed maturation appeared important. The proposed desirable genotype maintained specific dry matter accumulation rate during early seed fill but shifted to reduced seed maturation rate at a later stage of seed development.

Agronomic Characteristics That Identify High Yield, High Protein Soybean Genotypes

AbstractSeed yield and seed protein content are both heritable traits; however, breeding trials frequently reveal a negative correlation between the two traits. The objectives of this study were to measure and calculate various N‐dependent growth characteristics of soybean [Glycine max (L.) Merr.] and to determine their relation to seed yield and seed protein. Well‐nodulated plants, each fixing approximately 180 mg N during pod fill, were grown hydroponically in a growth chamber with or without NO3−N during pod filling. Twenty growth‐yield characteristics, including yield, harvest index, N harvest index, and Kjeldahl analysis of N2 fixation, were measured or calculated for each of the 384 plants examined. The highest seed yields, approximately 10 g plant−1, and the highest seed N contents, approximately 560 mg plant−1, were obtained when well‐nodulated plants were provided some fertilizer‐N during pod fill. Except for N content (%) of the dried plant, correlations between each pair of the 20 N‐dependent growth‐yield characteristics were generally positive. In the absence of fertilizer‐N during pod fill, however, N content (%) of the seeds did not correlate with either harvest index or N harvest index, suggesting that insufficient N during pod fill interferes with the orderly mobilization of foliar‐N to the developing seeds. New physiological parameters (seed yield merit, N yield merit, and merit of genotype) are proposed for the identification of genetic lines that produce both a high seed yield and a high seed protein content.

Seed Protein Content and Delivery of Assimilates to Soybean Seed Embryos

Increasing seed protein content in soybean [Glycine max (L.) Merr.] is associated with reduced seed yields. The objectives Of this study were to investigate the effects of seed protein content on the capacity to deliver dry matter and amino acids to the seed embryo and to identify possible yield‐limiting factors. Fifteen soybean genotypes representing 0.42 to 0.51 g g‐1 seed protein content were grown in the greenhouse during the winter season. High seed‐protein content did not limit specific dry matter accumulation rates. Removing side leaflets to reduce assimilate availability reduced assimilate uptake rates 21%. The reduced uptake rates were not associated with seed protein content. The modified seed structure associated with increased seed protein content did not limit rate of assimilate uptake by the seed. Thus, high seed protein content did not reduce sink activity. Genotypes with high seed protein content had higher rates of increase in seed density than the cultivar Ransom, indicating possible increased seed maturation rates for these genotypes. Rates of amino acid unloading from opened seed coats into a collection medium were associated With the seed protein content. The ratio of rate of amino acid unloading from opened seed coats to rate of dry matter delivery to the embryo was similar to the seed protein content. On the average, selecting for high seed protein content increased the capacity for amino acid production and transport and for amino acid unloading from the seed coat; however, additional factors were involved in the control, of seed protein content. A possible yield‐limiting factor, which is supported by the data on changes in seed density, is the capacity for amino acid unloading from the seed coat.

Yield and Composition of Soybean Seed from Parents with Different Protein, Similar Yield

Soybean [Glycine max (L.) Merr.] seed yields often show a negative association with seed protein. The objective of this study was to determine if this association could be minimized by crossing a high and a normal protein line of equal seed yield. An F2 population of 1000 plants was grown. Plants were harvested individually and seed evaluated for oil content using the nuclear magnetic resonance technique. Two bulk populations were developed: one included the 8% having the highest oil and the other the 8% having lowest oil. With the high negative correlation between seed protein and oil, the low oil population was expected to provide lines having high seed protein concentration. The two populations were advanced in bulk through the F6 generation, after which 200 plants were harvested individually from each population and 200 F7 lines grown from each. The F7 lines were harvested individually and seed analyzed for seed protein and oil. The 18 lines having the highest protein and the 18 lines having the highest oil were selected for further evaluation in replicated trials. Lines were evaluated in five environments for seed yield, protein, and oil. The overall mean seed yield of the high protein lines averaged 6% less than the overall mean of the lines selected for high oil; however, when seed yield of the two highest protein lines at each environment were compared with the two highest oil lines, the high protein lines had a 1% advantage in seed yield, an 18% advantage in seed protein, and a 20% reduction in oil. The results demonstrate the potential for developing soybean lines high in seed protein and equal in seed yield to lines having high oil content.

Shikimate Dehydrogenase‐12 Allozyme as a Marker for High Seed Protein Content in Rice

Recent studies at the International Rice Research Institute (IRRI) on the N‐assimilating isozymes in rice (Oryza sativa L.) showed that shikimate dehydrogenase high mobility allozyme (specified by the Sdh‐12 allele) was associated with higher protein accumulation. This study was conducted to verify such association in FI and F2 progenies derived from a cross involving parents differing in Sdh‐1 alleles and seed protein content, and to examine the influence of the Sdh‐12 allele on the Osborne's solubility fractions of total seed proteins. The female parent IR36 was characterized by the Sdh‐11 allele and low seed protein content, and the male parent IR480‐5‐9‐3‐3, by the Sdh‐12 allele and high seed protein content. The results indicated that the Sdli‐1 locus assorted in a monogenic mendelian fashion expressing codominance, while the seed protein content segregated in a polygenic manner. When F2 individuals were divided into three groups based on their Sdh‐1 allozyme pattern as determined by starch gel electrophoresis of seeds and tillers, the mean protein content per seed was highest (120.3 g kg−1 brown rice, BR) for Sdh‐12 homozygotes, intermediate (106.0 g kg− BR) for Sdh‐ll/Sdh‐12 heterozygotes, and lowest (91.9 g kg‐a BR) for Sdh‐11 homozygotes. Accumulation of the oryzenin fraction in the heterozygotes and Sdh‐12 homozygotes was significantly higher than in Sdh‐P homozygotes. Since oryzenin is the major component of seed storage proteins in rice, the Sdh‐12 allozyme can be an effective marker in screening for higher seed protein content among different cultivars or segregants from hybrid progenies.

Possibility of genetic improvement of pigeonpea (Cajanus cajan (L.)Millsp.) utilizing wild gene sources

Various wild relatives of pigeonpea,Cajanus cajan, namely some species ofAtylosia andRhynchosia, possess desirable characteristics that could be utilized for effecting genetic improvement of this crop. In total 73 cross combinations among two cultivars ofC. cajan and one accession each of eightAtylosia species and one ofRhynchosia were attempted. Twelve hybrids were obtained. Seven of these were analysed for F1 fertility and their utility for agronomic improvement of theC. cajan. Fertility behaviour of the different F1 hybrids varied and indicated that potential of gene transfer between the two genera,Atylosia andCajanus, was as good as within the genusAtylosia. From F2 and F3 families ofC. cajan × A. scarabaeoides andC. cajan × A. albicans, plants were selected with greater physiological efficiency and agronomic superiority. The prospects of transferring pod borer resistance and higher seed protein content from someAtylosia species to pigeonpea are discussed.

EFFECT OF SELECTION FOR PROTEIN ON LENGTHS OF GROWTH STAGES IN Glycine max × Glycine soja CROSSES

The effect of selection for high seed protein content on plant development in soybeans (Glycine max (L.) Merr.) was investigated by comparing the lengths of growth stages of four selected populations with those of a nonselected control. Each population, grown at two locations in one season, was a composite of four crosses between G. max and its putative wild ancestor, Glycine soja Sieb. and Zucc. The growth stages were planting to emergence, emergence to flowering and flowering to maturity. The length of each growth stage was measured in soybean development units (SDU) and in days. On average, populations selected for protein alone required more SDUs from planting to emergence and from emergence to flowering and fewer SDUs from flowering to maturity than did the control. The mean temperature in the stage from flowering to maturity was negatively correlated with protein content in all populations. The correlations ranged from −0.22* to −0.34**.

EARLY GENERATION SELECTION FOR PROTEIN IN Glycine max × G. soja CROSSES

Early generation selection for high seed-protein content would be desirable in breeding programs attempting to combine high yield and high protein content in soybeans (Gycine max (L.) Merr.). The heritability of seed-protein content in the F2 and F3 was measured in four crosses and mass and family selection for protein were compared in the F3 of these crosses. Glycine soja Sieb. and Zucc., a putative wild ancestor of the soybean, was the male parent in all crosses and selection intensity was at 10%. The heritability of protein in the F2, calculated by parent-offspring regression, was 27%. The broad-sense heritability of protein in F3 families grown over two locations in one season was 78%. Mean protein content for every selected population was greater (P ≤ 0.01) than the mean for the non-selected control population (45.3%). Mean protein contents of the F4 populations resulting from these selection methods were: mass selection in the F2 and F3, 48.0%; mass selection in the F3 following one generation of single seed descent, 48.8%; selection among F3 families, 47.6%; selection among and within F3 families, 47.5%. Either method of mass selection was superior to either method of family selection at the 0.01 level. Although early selection (mass or family) raised the mean protein content of a population, segregation continued to give rise to low-protein genotypes thereby requiring further selection.

Physiological aspects of nitrate utilisation in a barley variety exhibiting high seed protein content

AbstractA barley variety (Hiproly) which exhibits high seed protein content, was compared with the commercial variety, Ymer. Plants were raised to the seedling stage using a sand culture system. The effects of humidity, nutrient NŌ3‐N level, and stage of development, on leaf and root protein and NŌ3‐N contents, were assessed. The major difference between varieties was observed when the regression of leaf NŌ3‐N (mg/plant), on root NŌ3‐N (mg/plant) was examined. Unit increase in total root nitrate results in a larger increase in leaf nitrate in Hiproly than in Ymer. Possible explanations for this difference are discussed.