Genetic Analysis of Performance of Maize Inbred Lines Under Drought Stress

The majority of farmers in sub-Saharan Africa (SSA) depend on maize (Zea mays L.), which is mostly grown in drought-prone areas. Understanding the inheritance of drought tolerance would help in developing drought-tolerant maize hybrids that would help increase maize production under erratic rainfalls. Twenty-four maize inbred lines were subjected to NC design II to generate 96 single-cross hybrids. The 24 inbred lines and their 96 hybrids were evaluated under managed drought-stress conditions between 2002 and 2005 at Ikenne, Nigeria. The objectives of this study were to determine the effects of drought-susceptible and drought-tolerant inbred lines on performance of their hybrids, investigate mode of inheritance of drought tolerance, and determine the relationship between parental lines and their hybrids. Most crosses with at least one drought-tolerant parent produced tolerant hybrids, and the crosses between susceptible inbred lines produced susceptible hybrids. General combining ability (GCA) accounted for 55% to 87% of total variation among hybrids for most of the traits. Additive genetic effects influenced grain yield under drought stress. Correlation coefficient between grain yield of the inbred lines and their hybrids was positive and highly significant (r = 0.46***) under severe drought stress and relatively low (r = 0.30**) under mild drought stress and well-watered (r = 0.34**) regimes. Grain yield of inbred lines represented >20% of hybrid yield under severe stress. KU1409, 1824, 9006, 9432, and TZMI501xKU1414x501 had positive GCA effects for yield under drought stress and could be used for developing drought-tolerant hybrids.