Wednesday, November 15, 2006

Recovery of node removal on soybean using two plant populations.

Shawn Conley, Department of Agronomy, 915 West State St, 915 West State St, West Lafayette, IN 47907-2054, United States of America and Palle Pedersen, Dept. of Agronomy, "2104 Agronomy Hall, Iowa State Univ", "2104 Agronomy Hall, Iowa State Univ", Ames, IA 50011, United States of America.

Hail yield loss adjustments in soybean [Glycine max L. (Merr.)] are based on optimal populations.  As soybean seed input costs continue to increase growers are significantly lowering their seeding rate to achieve a targeted threshold population of 247,000 plants ha-1.  This change may dramatically impact current yield loss adjustments.  The objective of this study was to quantify the affect of soybean population, percent node removal, and node removal time on soybean grain yield and composition. Research was conducted in Iowa and Indiana in 2006. The experimental design was a randomized complete block design with four replications. The treatments were soybean stand population (333,300 and 247,000 plants ha-1), date of node removal (V1-V3, V4-V6, and R3), and percent node removal (0, 20, 40, 60, 80, and 100%).  Plots measured 3 by 7.6 m.  Our preliminary results indicated that yield loss was consistently greater at the 247,000 plants ha-1 treatment than at 333,300 plants ha-1; whereas soybean grain composition response to treatments varied. Our results suggest that hail yield loss adjustments may need modification if current trends to reduce soybean seeding rates continue.