Grain Sorghum Response to Row Spacings and Seeding Rates in Kansas

Abstract

Previous research suggests that reducing row spacings increased grain sorghum's [Sorghum bicolor (L.) Moench.] yield potential. However, most of this research was conducted in environments with lower yield potentials than currently found in northeast Kansas. The objectives of this study were to determine the impact that reducing row spacing had on grain sorghum grain yields and yield components. Research was conducted over five location-years in northeast Kansas to evaluate the effects of row spacings and plant populations on grain sorghum yields. Two hybrids were planted in 10, 20, and 30 in. rows at 30 000, 60 000, and 90 000 plants/acre. In environments where yields exceeded 100 bu/acre, yields were approximately 10% higher from the 10 and 20 in, rows than from the 30 in. rows. When moisture and temperature stress limited grain yields, no yield differences occurred among the row-spacing treatments. Grain yields responded little to changes in plant populations throughout the study. Reducing spacing per plant (reducing row spacing or plant populations) reduced panicles per plant. Caryopses per panicle and caryopses weights were affected primarily by growing conditions during their respective development periods. These results suggest that decreasing sorghum row spacing below 30 in, will increase grain yields under high yielding environments with little risk of reducing yields in lower yielding environments. This study also indicates that seeding rates do not have to be altered as narrow row systems are adopted.