Genetic studies under different levels of moisture stress in maize (Zea mays L.)

The genetic analysis carried out according to variety cross diallel model involving eight diverse maize composites possessing various levels of tolerance to moisture stress under optimum moisture and rainfed conditions revealed that the variance due to dominance effect was significant for days to 50% silking and tasseling, leaf area, plant height, cob width under both moisture situations. Variance due to additive effect, dominance effect GCA and SCA were significant for grain yield and test weight under both irrigated and rainfed conditions. The average heterosis x mating interaction was significant for grain yield under irrigated condition and for test weight for both the conditions. In our study, A-68 was one of the parents in crosses, which recorded highest heterobeltiosis under rainfed conditions for grain yield, plant height, and Cob width and cob length. The geritability values estimated on individual diallel sets revealed that test weight, plant height and cob width are highly heritable under both irrigated and rainfed conditions. While, heritability for yield was very low . The estimates of heritability also changed with mating systems. Thus , for breeding for moisture stress tolerance, indirect selection using highly heritable and highly correlated traits with yield will be an effective strategy. The correlation studies revealed that the grain yield was positively and significantly correlated with test weight, cob length, cob width, number of rows per cob and number of grains per cob under optimum moisture (I4), limited moisture (I2) and rainfed (I0) situations. The results revealed that cob width, number of grains per row and test weight were the common yield components across different moisture regimes. The multiple regression equation fitted to predict grain yield explained 47%, 37% and 26% of the variation in yield under I4, I2, I0, respectively. Thus, low leaf area in conjugation with more test weight, cob width and grains per tow form effective indirect selection criteria for grain yield under water stress situation.