Midsouthern USA Soybean Yield Affected by Maturity Group and Planting Date

Soybean ( Glycine max ) is planted from late March through June in the midsouthern USA due to time, production, and environmental constraints. These plantings may utilize cultivars from maturity groups (MG) IV through VII, and are grown in both nonirrigated and irrigated environments. In irrigated April and May plantings, MG IV cultivars produced greater yields with greater irrigation efficiency than did MG V, VI, and VII cultivars. In nonirrigated April plantings, MG IV and V cultivars produced yields similar to each other. In nonirrigated early‐May plantings, cultivars from all MGs produced similar yields, but days to maturity increased with increasing MG. In nonirrigated late‐May plantings, MG V through VII cultivars had greater yields, whereas MG VI and VII cultivars yielded the most in nonirrigated plantings made after 31 May. This study shows that planting cultivars that are later than necessary for maximum yield results in increased days to maturity and a concurrent greater risk of detrimental late‐season effects from drought and pests regardless of the planting date.