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ARS Home » Southeast Area » Stoneville, Mississippi » Crop Genetics Research » Research » Publications at this Location » Publication #256260
Title: Soybean seed protein oil and fatty acids are altered by S and N fertilizers under irrigated and non irrigated environments

Author
item Bellaloui, Nacer
item EBELHAR, M - Mississippi State University
item Gillen, Anne
item Fisher, Daniel
item Abbas, Hamed
item Mengistu, Alemu
item Reddy, Krishna
item PARIS, ROBERT - American Chestnut Foundation

Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/19/2011
Publication Date: 11/10/2011
Citation: Bellaloui, N., Ebelhar, M.W., Gillen, A.M., Fisher, D.K., Abbas, H.K., Mengistu, A., Reddy, K.N., Paris, R.L. 2011. Soybean seed protein oil and fatty acids are altered by S and N fertilizers under irrigated and non irrigated environments. Agricultural Sciences. 2:465-476.

Interpretive Summary: Soybean is a major source of protein and oil. In the Mississippi Delta, U.S.A., sulfur fertilizer has not been applied to the soybean crop because Delta soil has adequate nutrients. Generally, 10 units of nitrogen taken up by the plants require 1unit sulfur. Therefore, continuous removal of sulfur, a main component of sulfur-amino acids, from soil may affect soybean seed composition (protein, oil, and fatty acids). In addition, the change from conventional soybean production system to the Early Soybean Production System has shifted the time of oil and protein deposition to a warmer period, leading to possible change in the accumulation of protein, oil, and fatty acid rates. To test this hypothesis, a three-year field experiment was conducted in Stoneville, MS, to investigate the effects of sulfur alone and sulfur and nitrogen combined on seed composition. The results showed that under irrigation conditions, sulfur at a rate of 44.8 kg /ha alone or with nitrogen at 112 kg /ha resulted in a consistent increase in seed protein and oleic acid concentrations, and a decrease in oil and linolenic acid concentrations compared with the non-fertilized plots (control). The protein increases were 8.6% in 2005, 11.4% in 2006, and 8.4% in 2007 compared with the control. For oleic acid, the increases were 32.7% in 2005, 48.5% in 2006, and 26.4% in 2007. Oil decreased by 4.4% in 2005, 3.0% in 2006, and 8.8% in 2007. Protein and oleic acid increase was accompanied by a higher percentage of leaf and seed N and S. Under non-irrigated conditions, seed protein and oleic acid concentrations were significantly higher in control plots than in sulfur treatments (44.8 kg S/ha alone or 44.8 kg S/ha with N at 112 kg N/ha), but the oil and linolenic acid were significantly lower. In spite of the higher concentration of sulfur or sulfur with nitrogen combined under non-irrigated conditions, total protein and oleic acid (based on total seed yield, kg constituent/ha) were greater in sulfur treatments than in the control under irrigated conditions. The results indicate that application of 44.8 kg S/ha alone or 44.8 kg S/ha with N at 112 kg N/ha under irrigated condition can alter seed composition. The increased oleic acid under non-irrigated condition may indicate a possible physiological role of oleic acid in drought stress. This research provides useful information for the soybean processors to estimate total seed protein and oil in soybean produced in the Early Soybean Production System under irrigated and non-irrigated, and for soybean breeders to select for specific desirable seed composition constituent under environmental stress such as drought. Although soybean growers do not receive premium for a higher seed protein or oil, potential premium opportunities could be possible in the future, especially for specialty soybean uses such as tofu, soymilk, and other soy products. Unless the economics of fertilizer costs versus value-added gains is established, soybean growers may not fertilize for higher yield.

Technical Abstract: Effects of sulfur (S) or S + nitrogen (N) combined fertilizers on soybean [(Glycine max (L.) Merr.)] seed composition in the Early Soybean Production System (ESPS) under irrigated (I) and non-irrigated (NI) environments in the midsouthern U.S. have not been well investigated. A 3-yr field experiment was conducted from 2005 to 2007 to investigate the effect of different rates of S, and S combined with N (S+N) on seed protein, oil, and fatty acids (palmitic, stearic, oleic, linoleic, and linolenic), S, and N. Under I condition, S at a rate of 44.8 kg S/ha alone (T2) or with N at 112 kg N/ha (T6) resulted in a consistent increase in seed protein and oleic acid concentrations (g constituent/kg seed dwt), and a decrease in oil and linolenic acid concentrations compared with the control (C). Application of S+N resulted in an increase in protein percentage by 8.6% in 2005, 11.4% in 2006, and 8.4% in 2007 compared with C. For oleic acid, the increases were 32.7% in 2005, 48.5% in 2006, and 26.4% in 2007. Oil decreased by 4.4% in 2005, 3.0% in 2006, and 8.8% in 2007. Protein and oleic acid increase was accompanied by a higher percentage of leaf and seed N and S. Under NI conditions, seed protein and oleic acid concentrations were significantly higher in C than in any S or S+N treatments, but the oil and linolenic acid were significantly lower. Total (kg constituent/ha) protein and oleic were greater in T2 and T6 than C under I. However, the total protein and oleic acid were greater in C than other treatments under NI. The results indicate that S or S combined with N under irrigated condition can alter seed composition. The increased oleic acid under nonirrigated condition may indicate a possible role of oleic acid in drought stress. This research provides useful information for the soybean processors to estimate total seed protein and oil in soybean produced in ESPS, and for soybean breeders to select for specific desirable seed composition constituent under environmental stress such as drought.