Effects of Salinity, Imazethapyr, and Chlorimuron Application on Soybean Growth and Yield

Soybean is an important crop worldwide. Soybean cultivars differ in their sensitivity to soil salinity and herbicide damage. In these experiments, we examined the impact of salinization and herbicide (imazethapyr and chlorimuron) application on the growth and yield of two soybean cultivars, Essex and Manokin. Experiments were conducted in small pots in the greenhouse, in outdoor sand cultures, and in drip-irrigated field plots. Plants were irrigated with non-saline water or saline water (electrical conductivity, EC 1⁄4 7 dS/m) with a composition typical of those in areas affected by sulfate-dominated salinity. Morphological changes resulted from herbicide application, including leaf elongation and formation of large shoots at the cotyledonary node. Herbicide treatment significantly reduced main stem height, number of nodes on the main stem, and stem diameter relative to the controls (not treated with herbicide); responses from the two herbicides were not significantly different. Salinity had a significant effect on seed weight: yield for “Essex” (a Cl accumulator) was significantly higher when irrigated with fresh water, while yield for “Manokin” (a Cl excluder) was significantly larger for plants irrigated with saline water. Yield for “Essex” was greater than that for “Manokin” when the plants were irrigated with fresh water; but at the higher irrigation water salinity (7 dS/m), Received 12 December 2003, Accepted 27 July 2004 Address correspondence to Sharon K. Papiernik, United States Department of Agriculture, Agricultural Research Service, Soil Management Research, 803 Iowa Avenue, Morris, MN 56267, USA. E-mail: [email protected] Communications in Soil Science and Plant Analysis, 36: 951–967, 2005 Copyright # Taylor & Francis, Inc. ISSN 0010-3624 print/1532-2416 online DOI: 10.1081/CSS-200050280 “Manokin” produced significantly greater yield than “Essex.” Although herbicide application significantly impacted several growth variables, herbicide treatment had no significant impact on yield.