SCREENING FOR MOISTURE DEFICIT TOLERANCE IN FOUR MAIZE (Zea mays L.) POPULATIONS DERIVED FROM DROUGHT TOLERANT INBRED X ADAPTED CULTIVAR CROSSES.

Abstract

Efficiency of soil water utilization under moisture deficit condition can help reduce the adverse effects of drought stress in crops. Growth, physiological responses and grain yield loss due to moisture deficits around flowering, were investigated in maize populations derived by reciprocal crosses between two adapted maize cultivars (DMR-LSR-Y and AFO) and two drought tolerant (DT) inbred lines (DT-S3-Y and DT-S3-W) under glass house conditions. The crosses and their parents and crosses were subjected to irrigation treatments equivalent to 25, 50, 75 and 100% field capacity (FC) as well as water withdrawal for two weeks at vegetative, pre and post-anthesis stages respectively.  Reduction in biomass yield (BMY) under low moisture regimes were within the range of 75 to 61% of BMY obtained under favourable irrigation treatments while Pre and post- anthesis moisture deficits also significantly reduced grain yield by 49 and 66% of well-watered condition. Reciprocal crosses between AFO and DT-S3-Y consistently gave highest BMY under irrigation treatment equivalent to 75% FC and above with % gains ranging from 3.05 to 44.2 respectively. All crosses except two of them (DT-S3-Y x AFO and AFO x DT-S3-W) evidenced superiority for BMY and water use efficiency (WUE) over their respective better parents, under low moisture conditions. Heterotic response for grain yield differed among crosses depending on soil moisture condition. There was no direct association between drought sensitivity index (DSI) and grain yield in the populations but genotypes with short anthesis-silking-interval (ASI) under moisture deficit conditions showed superiority for grain yield over those with longer ASI. The above results suggest that short ASI when combined with high grain yield under moisture deficit conditions is a better selection tool for identifying drought tolerant genotypes than DSI.