Influence of planting date on seed protein oil sugars minerals and nitrogen metabolism in soybean under irrigated and non-irrigated enviroments

Authors: Bellaloui, Nacer; Reddy, Krishna; Gillen, Anne; Fisher, Daniel; Mengistu, Alemu

Submitted to: American Journal of Plant Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/20/2011
Publication Date: 11/9/2011
Citation: Bellaloui, N., Reddy, K.N., Gillen, A.M., Fisher, D.K., Mengistu, A. 2011. Influence of planting date on seed protein oil sugars minerals and nitrogen metabolism in soybean under irrigated and non-irrigated enviroments. American Journal of Plant Sciences. 2:702-715.

Interpretive Summary: There is limited information on the effect of planting date and irrigation on soybean seed composition components (protein, oils, sugars, and minerals) in the Early Soybean Production System, and what information is available is inconclusive. Therefore, the objective of this research was to investigate the effects of planting date on seed protein, oil, fatty acids, sugars, and minerals in soybean grown under irrigated and non-irrigated conditions. A two-year field experiment was conducted in Stoneville, MS in 2007 and 2008. Soybean was planted during the second week of April (early planting) and second week of May (late planting) each year. Results showed that under irrigated condition, early planting increased seed oil up to 16% and oleic acid up to 22.8%, but decreased protein up to 6.6%, linoleic up to 10.9%, and linolenic acids up to 27.7% compared to late planting. Under irrigated condition, late planting resulted in higher sucrose (desirable sugar) and raffinose (undesirable sugar) and lower stachyose (undesirable sugar) compared with early planting. Under non-irrigated conditions, seed of early planting had higher protein (up to 4% increase) and oleic acid (up to 25%) and lower oil (up to 10.8% decrease) and linolenic acid (up to 13% decrease) than those of late planting. Under non-irrigated conditions, stachyose concentration was higher than sucrose or raffinose, especially in early planting. Seed of late planting accumulated more boron, phosphorus, and iron than those of early planting. This research demonstrated that both planting date and irrigation management influenced seed composition components. These findings are beneficial to soybean growers for soybean management to maintain yield and seed quality, and to soybean breeders to select for seed compositional traits in stress environments.

Technical Abstract: Information on the effect of planting date and irrigation on soybean [Glycine max (L.) Merr.] seed composition in the Early Soybean Production System is deficient, and what is available is inconclusive. The objective of this research was to investigate the effects of planting date on seed protein, oil, fatty acids, sugars, and minerals in soybean grown under irrigated (I) and non-irrigated (NI) conditions. A 2-yr field experiment was conducted in Stoneville, MS in 2007 and 2008. Soybean was planted during second week of April (early planting) and second week of May (late planting) each year. Results showed that under irrigated condition (I), early planting increased seed oil (up to 16% increase) and oleic acid (up to 22.8% increase), but decreased protein (up to 6.6% decrease), linoleic (up to 10.9% decrease) and linolenic acids (up to 27.7% decrease) compared to late planting. Under I conditions, late planting resulted in higher sucrose and raffinose and lower stachyose compared with early planting. Under NI conditions, seed of early planting had higher protein (up to 4% increase) and oleic acid (up to 25%) and lower oil (up to10.8% decrease) and linolenic acids (up to 13% decrease) than those of late planting. Under NI, stachyose concentration was higher than sucrose or raffinose, especially in early planting. Under I, early planting resulted in lower leaf and seed B, Fe, and P concentrations compared with those of late planting. Under NI, however, early planting resulted in higher accumulation of leaf B and P, but lower seed B and P compared with those of late planting. This research demonstrated that both irrigation and planting date have a significant influence on seed protein, oil, unsaturated fatty acids, and sugars. Our results suggest that seed of late planting accumulate more B, P, and Fe than those of early planting, and this could be a beneficial gain. Limited translocation of nutrients from leaves to seed under NI is an undesirable. Soybean producers may use this information to maintain yield and seed quality, and soybean breeders to select for seed quality traits and mineral translocation efficiency in stress environments.