Wednesday, November 15, 2006

Effect of node removal on soybean grain yield and composition.

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

Soybean [Glycine max L. (Merr.)] producers across the United States are confronted with significant yield losses every year from severe hail storms. A lot of research has been conducted on the impact on soybean physiology and recovery in response to defoliation. However, little information exists in response to soybean node removal which could influence replant decisions. The objective of this study was to test the ability of soybean recovery to node removal at different growth stages on soybean grain yield and composition. Research was conducted in Iowa and Indiana from 2003 to 2006. The experimental design was a randomized complete block design with four replications. The treatments were date of node removal (V1-V3, V4-V6, and R3 in Iowa and V1-V3 and V4-V6 in Indiana) and six levels of node removal (0, 20, 40, 60, 80, and 100%). Plot size was 3 by 7.6 m. Data from the two states were consistent with the greatest seed yield reductions occurring at R3, followed by V4-V6, and with the smallest yield loss at V1-V3 (up to 10%). Plants were not able to recover from a 100% node removal after V3. Regardless of plant growth stage, increasing the level of node removal decreased the seed mass, plant height, and final plant population but increased the protein and oil content. The data indicates that node removal timing affects grain yield and should be considered in a replant decision.