ARS | Publication request: IDENTIFICATION OF THE TEMPERATURE THRESHOLD FOR SOYBEAN IRRIGATION

Submitted to: Soybean Research World Conference Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: August 7, 1999
Publication Date: N/A

Technical Abstract: Studies of plant temperature characteristics have shown species-specific temperature optima for growth and development. The information on the temperature characteristics of plant metabolism has been used to develop an irrigation scheduling technique that maximizes the time a crop is at its temperature optima. This study evaluates the effectiveness of the laboratory determined temperature optimum for soybean for use in managing irrigation of soybeans in the field. Identification of the optimal temperature for soybean metabolism was determined by the analysis of the thermal dependence of the reappearance of Photosystem II variable fluorescence showing a range of favorable temperatures between 26 and 28C. A temperature of 27C was selected based upon the chlorophyll fluorescence analysis. This temperature has been used as the threshold temperature for irrigation scheduling via the BIOTIC (biologically-identified optimal temperature interactive console) system. To apply a slightly more stressfu irrigation regime, a second threshold temperature of 29C also was evaluated. A comparison of irrigation scheduling of soybeans via BIOTIC with traditional irrigation scheduling using soil profile water content measurements showed that the BIOTIC system provided maximum yields equivalent to full water replacement. The yield under these well-watered conditions approached 80 bu/ac, nearly doubling those typically obtained in the Southern High Plains. This study shows that irrigating soybeans to maximize the time that they are within their biochemical temperature optima maximizes yields.