Maturity group of grain sorghum

Grain sorghum varieties and hybrids are classified as early-maturing (90–105 days), mid-maturing (106–120 days), and late-maturing (120–130 days or more). The growing period is calculated as the time interval from emergence to the onset of the physiological grain maturity stage.

Sorghum is a short-day crop; therefore, when the day length decreases to less than 10–11 hours, the growing period until flowering can increase by 3 weeks or more. This characteristic requires adjusting the choice of maturity group depending on the latitude of cultivation to prevent grain from failing to mature before frosts.

This trait determines agronomic management aspects, including seeding density and harvesting strategy. Early-maturing hybrids require higher plant populations due to fewer grains per panicle, and their harvest timing helps reduce risks of crop damage by pests and mycotoxins.