Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 4, 2011
Publication Date: N/A
Interpretive Summary: Soybean nitrogen traits are important for seed production and variability in traits may hold potential for further improvements in seed yield and quality. In this study we examined a wide range of soybean lines in various field experiments and found significant variation in leaf, petiole, and stem nitrogen concentrations. We also used molecular markers analysis to identify genes associated with stem nitrogen concentration and to gain insight into the inheritance of stem nitrogen. We found significant relationships between the various tissue nitrogen traits with seed yield and quality. This study illustrates the importance of nitrogen dynamics in vegetative tissues of soybean for yield and seed composition. Additionally, selection for vegetative nitrogen traits could increase yield and improve seed quality.
Technical Abstract: Soybean [Glycine max (L.) Merr.] shoot N traits are important for seed production and may hold potential for further improvements in seed yield and quality. Field experiments were established to survey shoot N traits in: (i) selected soybean plant introductions from the National Soybean Germplasm Collection maturity groups V through VIII, (ii) a recombinant inbred line (RIL) population, and (iii) modern soybean cultivars. A wide range of nitrogen concentrations among the plant introductions was observed at beginning seed fill (R5) for leaf (25 to 64 g kg-1), petiole (8 to 32 g kg-1), and stem (8 to 25 g kg-1) and at maturity (R8) for stem (5 to 10 g kg-1). In the modern soybean cultivars, N concentrations for those tissues ranged between 35 and 55 g kg-1 for R5 leaf, 12 and 25 g kg-1 for R5 petiole, 11 and 28 g kg-1 for R5 stem, and between 7 and 12 g kg-1 for R8 stem. Stem N concentrations in the RIL population were between 8 and 21 g kg-1 at R5 and 5 and 11 g kg-1 at R8. Molecular marker analysis of the RIL population identified multiple loci associated with stem N concentration and indicated multi-genic inheritance. Significant relationships of various tissue N traits with seed yield and quality were observed. In the modern soybean cultivars, stem N concentration at R5 was positively related to seed yield and oil concentration and negatively related to protein concentration. In contrast, in the RIL population, protein concentration was positively related to R5 stem N concentration. These results illustrate the importance of N dynamics in vegetative tissues for soybean yield and seed composition. In combination with the large range in N traits observed among lines in the soybean germplasm collection and the RIL population, the observed relationships indicate that selection for vegetative N traits could potentially increase yield and improve seed quality.