Management effects on lowest pod placement and yield formation in soybean.

Abstract

Chapter Summary: In recent years, increased harvest loss for soybean [Glycine max (L.) Merr.] due to low forming pods has been noted in southern Minnesota. These harvesting losses come from the inability of the cutterbar on harvesting equipment to be operated close enough to the soil surface to gather low formed pods. In order to better understand the effects of management strategy on height and nodal characteristics and their relation to lowest pod height, studies were conducted in the southern Minnesota region in 2008 and 2009 to investigate plant density, relative maturity, row width, mulch color, and stand reduction. Increasing population density from 19 to 43 plants m-2 increased the height of the lowest pod from 12.2 to 15.8 cm. The relative maturity of soybean varieties also affected the height of the lowest pod, increasing it from 10.9 to 18.8 cm going from a late MG 0 and a late MG II variety. Changes in row width revealed there was no significant effect on the height of the lowest pod. Red colored mulch produced a significantly higher lowest pod height at 14.7 cm compared to no mulch which had a height of 13.0 cm. Stand reduction studies revealed that lowest pod height could be reduced from 15.9 to 11.5 cm when population was reduced from 43 to 19 plants m-2 as late as R3. Only population density was found to affect LPH and internode length simultaneously, so the impacts seen on LPH do not appear to be primarily working through differences in internode length.