INHERITANCE OF THE STAY GREEN TRAIT IN SORGHUM

Stay green is an important trait associated with drought resistance in sorghum [Sorghum bicolor (L.) Moench]. This study was conducted to obtain preliminary information on the mode of gene action for the stay green trait in sorghum. Stay green inbred line (B35), nonstay green inbred line (Tx7000), and their F-1, F-2, and backcrosses were grown in the field and under a rainout shelter in Lubbock, TX. Moisture stress was allowed to develop in both trials during the grain filling period by witholding irrigation 2 wk prior to flowering. Stay green was evaluated on an individual plant basis at or soon after physiological maturity by using a visual leaf and plant death rating score. The results suggest that the stay green traits in B35 is influenced by a major gene that exhibits varied levels of dominant gene action depending on the environment in which evaluations are made.