Combining, Earliness, Short Anthesis To Silking Interval And Yield Based Selection Indices Under Intermittent Water Stress To Select For Drought Tolerant Maize

Abstract

Maize , the most important staple crop in Kenya , is affected by drought stress at flowering period leading to low yields. Past studies at CIMMYT have demonstrated that a short Anthesis to Silking Interval (ASI) is an important component of drought tolerance in maize. In this study, one hundred and thirty five F 2 ;F 3 progenies developed from crosses between long ASI, Ka tumani composites and short ASI, elite CIMMYT genotypes were evaluated for grain yield under drought stressed and well - watered environments, in two seasons in an alpha lattice design of three replications. ASI was significantly negatively correlated with g rain yield (GY) under stress ( - 0.446) but not under well watered condition. ASI was significantly positively correlated with stress susceptible index (SSI) (0.304) but was highly negatively significantly correlated with stress tolerance index (STI) ( - 0.378 ). ASI was also significantly positively correlated with geometric mean productivity (GMP) ( - 0.448), mean productivity (MP) ( - 0.419), and yield stress index (YSI) ( - 0.303). Among the computed drought tolerance selection indices, GMP and GY were highly posi tively correlated with other drought selection indices and negatively correlated with ASI. These two traits are likely to be better measures of drought t olerance than all the other indices. F 3 families from KDV2/CML444 - 14 and KDV2/CML440 - 224 generations were earlier maturing, higher yielding, a shorter ASI and higher WUE and GMP indices than the other genotypes, under drought stressed environments. It is possible to combine earliness and ASI in developing high yielding, early maturing drought tolerant m aize for arid and semi - arid areas of Kenya.