Soybean (Glycine max L. Merr.) seed composition response to soil flooding stress

Soybean is a valuable commodity due to its high oil and protein content and its nutritional and functional food value. Changes in soybean seed composition by environmental stressors including heat and drought have been documented, but the effects of flooding are not yet known. This study profiles the change in seed composition of five soybean plant introductions (PIs) tolerant to flooding stress and the flooding sensitive check cultivar Williams in three environments. The results showed that flooding did not significantly affect seed protein, oil or palmitic acid, but increased oleic and stearic acid levels in all genotypes. However, the linoleic and linolenic acids, daidzein, genistein, and glycitein contents were significantly reduced in all genotypes. The effects of environment were significant for most seed composition traits under flooding stress, except palmitic acid, linolenic acid and glycetin. Single degree of freedom orthogonal comparison showed that seed quality index (SQI) a composite indicator of seed quality increased by 4% in the PIs, but decreased by 5% in the check cultivar. The results suggested that SQI is a useful criterion when genetic selection for seed composition is to be made in different environments. Given the more frequent extreme weather patterns possible with global climate change, caution is needed in the selection of environments for testing and producing soybeans for special composition traits.