Soybean seed protein, oil, and fatty acids are altered by S and S + N fertilizers under irrigated or non-irrigated environments

Nacer Bellaloui,Hamed K Abbas,Krishna N Reddy,Daniel K Fisher,M Wayne Ebelhar,Robert L Paris,Alemu Mengistu,Anne M Gillen

doi:10.4236/as.2011.24060

Abstract

Information on the effect of sulfur (S) or sulfur+nitrogen (S + N) on soybean seed composition is scarce. Thus, the objective of this study was to investigate the effects of S, and S + N fertilizers on soybean [(Glycine max (L.) Merr.)] seed composition in the Early Soybean Production System (ESPS) under irrigated (I) and nonirrigated (NI) environments. Two separate field experiments were conducted from 2005 to 2007. One experiment was irrigated, and the second experiment was nonirrigated. Under I condition, S at a rate of 44.8 kg/ha alone or with N 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 control (C). For example, in 2006 and compared with the C, application of S + N increased the percentage up to 11.4% and 48.5% for protein and oleic acid, respectively. However, oil concentration decreased by 3%. Protein and oleic acid increase were 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 concentrations were significantly lower. The results indicate that specific rate of S alone or S + N combined can alter seed composition under irrigated or nonirrigated conditions. This knowledge may help plant breeders to develop and release cultivars to suit specific target locations to grow new value-added soybeans or select for specific seed composition traits under specific environmental stress factors such as drought.

Highlights

Soybean is a major source of high nutritional quality protein and oil [1], and its economic value can be determined by seed protein and oil content
The objective of this study was to investigate the effects of S alone or S combined with N fertilizer on soybean seed protein, oil, fatty acids, and the physiological dynamics of leaf and seed S and N concentration under irrigated and nonirrigated conditions in Early Soybean Production System (ESPS)
Different rates of S and S combined with N fertilizer were supplied as follows: Control (C) = 0 kg·S/ha + 0 kg·N/ha; Treatment 1 (T1) = 22.4 kg·S/ha + 0 N; Treatment 2 (T2) = 44.8 kg·S/ha + 0 N; Treatment 3 (T3) = 67.2 kg·S/ha + 0 N; Treatment 4 (T4) = 0 kg·S + 112 kg·N/ha; Treatment 5 (T5) = 22.4 kg·S/ha + 112 kg·N/ha; Treatment 6 (T6) = 44.8 kg·S/ha + 112 kg·N/ha; Treatment 7 (T7) = 67.2 kg·S/ha + 112 kg·N/ha

Summary

Introduction

Soybean is a major source of high nutritional quality protein and oil [1], and its economic value can be determined by seed protein and oil content. The concentration of saturated fatty acids in soybean oil ranges from 100 to 120 g/kg for palmitic acid and from 22 to 72 g/kg for stearic acid [3]. The mean concentration of unsaturated fatty acids in oil is 240 g/kg for oleic acid, 540 g/kg for linoleic acid, and 80 g/kg for linolenic acid [4]. In the midsouthern USA, soybean is produced under both irrigated and non-irrigated conditions, with about 50% of soybean grown in the Mississippi Delta nonirrigated. This is mainly because soybean yield varies from season to season due to varying environmental conditions such as soil type, rainfall, temperature, and management practices [5]. The yield in ESPS has been shown to be higher under both irrigated and Openly accessible at http://www.scirp.org/journal/AS/

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