Soybean seed protein, oil, fatty acids, N, and S partitioning as affected by node position and cultivar differences

Abstract

The mechanisms controlling the partitioning of seed composition constituents along the main stem in soybean are still controversial. Therefore, the objective of this study was to investigate seed protein, oil, and fatty acids partitioning in soybean cultivars along the main stem. The cultivars were DT97-4290, maturity group (MG) IV; Stressland, MG IV; Hutcheson, MG V; TracyM, MG VI. Seeds were harvested based on position on the plant (top nodes, middle nodes, and bottom nodes). At R8 (physiological maturity stage), DT97-4290, Hutcheson, and Stressland had higher percentage of protein and oleic acid and lower percentage of oil and linolenic acid in top node seed compared with bottom node seed. The increase of protein in top node compared with the bottom node across the two experiments ranged from 15.5 to 19.5%, 7.0 to 10.5%, 14.2 to 15.8%, 11.2 to 16.5%, respectively for DT97-4290, Hutcheson, Stressland, and TracyM. Except for TracyM, the increase of oleic acid in the top node ranged from 45.4 to 93%, depending on the cultivar. Conversely, the decrease in the top node seed ranged from 14.4 to 26.8% for oil and from 5.7 to 34.4% for linolenic acid, depending on the cultivar. The partitioning trend of seed composition constituents at R6 (seed - fill stage) was inconsistent. Except for Stressland, seed oleic acid was higher at R6 than at R8. The higher protein and oleic acid concentrations in the top node seed was accom- panied by higher activity of nitrate reductase activity, higher chlorophyll concentration, higher nitrogen (N) and sulfur (S) percentages in the fully expanded leaves at R5-R6 growth stage, and higher seed nitrogen (N) and sulfur (S) percentages in DT 97-4290 and Stressland. The current research suggests that the partitioning of seed protein, oil, and fatty acids in nodes along the plant depended on the position of node on the main stem, cultivar differences, seed N and S status, and tissue N and S partitioning. The higher nitrate reductase activity at the top nodes, accompanied higher protein and oleic acid, and the changes of oleic acid at R6 and R8 along the stem, were not previously reported, and need further investigation. The current knowledge is useful for soybean germplasm selection for desirable traits such protein and oleic acid, and for accurate measurements of seed composition constituents in breeding lines

Effect of pods' position on the protein content in soybean grains at low latitude

“…These results are in agreement with those obtained by Zanon 27 , whose protein ranges from 30% to 45% by Bennett et al 17 , ranging from 36% to 40% and Bellalou and Gillen 15 , ranging from 40% to 48.6%.…”

“…For the other cultivars, it was not detected significant differences between the pods' position on the main stem although in magnitude, a higher average protein content was observed for middle and top position. Minors concentration of protein in the basal region of the plants are due to a lower photosynthetic leaves' activity of this region, by the effect of shading 15 as well as leaf senescence of this region 23 , during the grain filling stage, resulting in a smaller nitrate assimilation, and consequently a lesser protein synthesis.…”

“…Protein content might still vary according on climatic conditions 8,9 , Cultivars 10 , fertilization levels [11][12][13] , leaf removal and pods 14 , shading 14,15 ; and pods' position in the main stem of the plant [15][16][17][18][19] . Regarding the effect of pods' position in the main stem of the plant, numerous v indicated that the grains located on the top of the plant has higher protein concentration than grains from the bottom of the plant [15][16][17] . On the other hand, a survey conducted by Huskey et al 20 reported there was no significant difference in protein content for soybean grain between the upper third of and lower third of the plant which, in turn, were higher than the intermediate third.…”

Teor de óleo e proteína em grãos de soja em diferentes posições da planta

“…Para o terço superior, o grupo com médias maiores que 42% de proteínas (FMT Tucunaré e BRSMT Pintado); menor Teor de óleo e proteína em grãos de soja em diferentes posições da planta Tabela 4 -Teor médio de óleo de grãos de soja (15 cultivares) localizados em diferentes posições na haste da planta (terço inferior, médio e superior), nos anos agrícolas (2011/12 e 2012/13), em condições de baixa latitude,Palmas-TO A maioria das cultivares, com exceção da BRS Valiosa, apresentaram diferenças significativas quanto ao teor de óleo, para as diferentes posições das vagens na haste da planta, sendo os maiores valores observados nos terços inferior e médio. Diversos trabalhos relatam, menor concentração de óleo em grãos de soja nas vagens no terço superior (BENNETT et al, 2003;BELLALOUI;GILLEN, 2010;SALES et al, 2013). Entretanto, as cultivares P99R03 (24,01%), BRSMT Pintado (21,97%), M9144RR (21,49) e M8867RR (17,89) apresentaram os maiores teores de óleo em grãos no terço superior e médio (Tabela 4).…”

“…Alguns autores indicam fatores que interferem nos teores de proteína e óleo do grão de soja, tais como: sombreamento (PROULX; NAEVE, 2009;BELLALOUI;GILLEN, 2010), remoção de vagens e folhas (PROULX; NAEVE, 2009) e posição das vagens nos nós da haste da planta (HUSKEY et al,1990;BENETT et al, 2003;BELLALOUI;GILLEN, 2010;SALES et al, 2013).…”