Response of soybean yield components to management system and planting date

Soybean [Glycine mar (L.) Merr.] area has increased tremendously in the upper Midwest over the last decade, but little information exists regarding the impact of management systems on soybean yield components. Our objective was to assess the effect of management system and planting date on soybean seed yield components and their development for environments typical of the upper Midwest. A field study was conducted from 1997 to 2000 using five management systems. Two newer released cultivars (CX232 and Spansoy 250) and one older cultivar (Hardin) were planted at two planting dates. Few interactions were observed in this study. Management system influenced development of the different yield components and produced seed mass ranging from 10.5 to 16.5 g 100 seed(-1), seed number from 2878 to 3824 seeds m(-2), pod number from 1182 to 1571 pods m(-2), and seeds per pod from 2.36 to 2.49 seeds pod(-1). Harvest index ranged from 56.2 to 58.0% across management systems. Hardin produced the highest harvest index (60.1%) and Spansoy 250 the lowest harvest index (54.5%). Tillage system affected yield components, with no-tillage systems having 15, 9, and 9% greater seed mass, seed number per square meter, and pod number per square meter than the conventional tillage system, respectively. Early planting date produced higher seed number, pod number, and harvest index but lower seed number per pod than the late planting date. In conclusion, differences in yield components and their development emphasize the complexity of plant compensation in response to management system and tillage system.