Soybean Development in the Midsouthern USA Related to Date of Planting and Maturity Classification

Abstract

Soybean (Glycine max) is planted from late March through June in the midsouthern USA. Different developmental patterns that result from this range in planting dates will affect management decisions. Irrigated field studies were conducted at Stoneville, MS (33° 26′N) from 1979 through 2003 to determine effect of late March through June planting dates on developmental patterns of maturity group (MG) IV through MG VI soybean. In all plantings, time from planting to beginning bloom (R1) increased as MG increased from IV to VI. Time from R1 to full seed (R6; pod cavity filled) was sometimes but not always different among the MGs, and differences were always ≤ 7 days. The major difference in the length of growing season among cultivars of different MGs occured before reproductive development began regardless of planting date. Thus, performance of soybean cultivars of disparate MGs should not be affected by differences in time between stages of reproductive development, but rather by when the stages occur.