Early Planted, Early Maturing Soybean Cropping System: Growth, Development, and Yield

Abstract

Abstract An early planted, early maturing soybean [ Glycine mar (L.) Merr.] cropping system could stagger harvest maturity and increase the number of options available for subsequent crops. However, premature flowering of early maturing cultivars could reduce canopy closure at flowering (CCR1) or at beginning seed fill (CCR5) as well as vegetative mass at R5 (VMR5). This study was conducted to determine the Maturity Group (MG) best suited for this early planted cropping system, and to relate growth, development, and environmental parameters to yield. Two cultivars each from MG 00,0,I,II,III, and IV were planted in six Kentucky field environments ranging from 36°40' to 38°7'N lat from 1986 to 1989. Vegetative, pod‐set, and seed‐fill durations were generally shorter in early‐maturing cultivars, but also interacted with environment. Maturity groups 00 and 0 had inadequate canopy closure at R1 and R5, inadequate vegetative mass at R5, and produced lowest overall yields. While MG I and II appeared to be most sensitive to vegetative and pod‐set rainfall and seed‐fill temperatures, MG II produced the best mean yield. Seed‐fill duration and rainfall were apparently more important for MG III and IV than for earlier MGs. Maturity Group II appears to be more adaptable than other MGs in these early planted, early maturing soybean cropping systems in Kentucky.