Effect of Planting Practices On Light Interception, Growth and Yield of Grain Sorghum.

Grain sorghum is well adapted to semi-arid environments, but production practices must be optimized. A two-year study was conducted at four locations to determine the effects of  planting date, hybrid maturity, row spacing and plant density on sorghum growth and yield. The hypothesis was that the combination of hybrid maturity, row spacing and plant density that maximizes yields will differ depending on planting date, latitude, available moisture and light intercepted. The experiments were conducted at Belleville, Ottawa, Hutchinson and Manhattan in 2009 and 2010 at the experiment fields of Kansas State University. The experimental design was a split-split plot with four replications. Weed control was accomplished with a pre-emergence application of dimethenamid–P and atrazine. Treatments were two planting dates (late May and mid June), two hybrids maturity (Medium Early, DKS44-20  and  Medium Late, DKS 53-67), two row spacing (25  and 75 cm) and 4 plant  densities (50000, 80000, 110000 and 140000 plants/hectare ). Dry matter and light interception were recorded at 45, 60 and 95 days after planting. The early planting date (late May) produced the best yields across all locations. Row spacing (25 cm) that provided the most equidistance spacing for plants produced the best plant growth and grain yield across all locations. Hybrid maturity did not influence grain yield in all environments. Results indicate that early planting (late May) at plant population of 80000 plants/ hectare in narrow rows (25 cm) can maximize light interception, biomass production and grain yield of sorghum.