Submitted to: Irrigation Science
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/6/2007
Publication Date: 10/9/2007
Citation: Bellaloui, N., Mengistu, A., 2007 Seed Composition is Influenced by Irrigation Regimes and Cultivar Differences in Soybean. Irrigation Science. DOI 10.1007/s00271-007-0091-y Interpretive Summary: Drought is a major environmental stress in soybean production in the mid-southern United States. The Early Soybean Production System is based on planting shorter-season varieties, such as those adapted to the northern regions, in April or earlier to avoid drought. Use of this system results in increased yield and profit compared to later plantings of longer-season varieties. Although the Early Soybean Production System has been successfully implemented under both irrigated and non-irrigated conditions, little has been done to assess the effect of drought stress on seed composition. The effects of soybean variety and timing of irrigation application on oil, fatty acid and protein content was determined. The amount of oil, fatty acid, and protein in soybean seeds was significantly influenced by soybean variety, irrigation timing, and growing season within a range of 2% for oil and up to 5% for protein. Farmers may increase desired soybean seed compositional traits without sacrificing yield by careful selection of soybean varieties which are then managed with appropriate irrigation practices.
Technical Abstract: Although the early soybean production system (ESPS) has been successfully implemented in the southern U.S. and has resulted in significant yield increase, little has been done to assess the effect of irrigated and non-irrigated soil conditions on seed composition. The current study was designed to evaluate the interaction of genotypes and irrigation treatments [(Full-Season Irrigation (FS), Reproductive stage Irrigation (RI), and Non-Irrigation (NI)] on the concentration of oil, fatty acid (palmitic, stearic, oleic, linoleic, and linolenic), and protein concentration. Concentration of oil, fatty acid, and protein in seeds was significantly influenced by genotype, irrigation, and growing season. In 2002, 2003, and 2004, the highest concentration of oil was consistently recorded in Dwight (MG II), DP4748 (MG IV), and DK3964 (MG III). Whereas, the lowest concentration of oil was observed in Freedom (MG V). In 2004, the concentration of linoleic and linolenic acids were significantly higher in DK3964 under RI and FS. NI caused an increase in oleic acid concentration in DK3964, increased from 20.3 %, under RI, to 25%, under NI. Although Dwight and DP4748 had a higher total oil concentration, their linoleic acid concentration was lower than DK3964 and Freedom. In 2004 and under NI, Dwight consistently showed the lowest accumulation of protein. Full Season Irrigation, however, caused a significant increase in protein concentrations in Dwight. The results indicate that irrigation interacted with genotypes to significantly affect seed composition. There were nitrogen or sulfur content in seeds effects on seed composition. This is the first detailed report on the effect of variable irrigation on seed composition.