Influence of Deficit Irrigation at Silking Stage and Genotype on Maize (Zea mays L.) Agronomic and Yield Characters

Maize is considered susceptible to drought stress, when occurs at flowering stage. Thus, the development of drought tolerant maize cultivars is of important priority for plant breeders. The objectives of the present study were: (i) to assess the effect of maize genotype (G), irrigation (I) regime and their interaction on agronomic and yield characters and (ii) to identify drought tolerant and high yielding genotypes under water stress conditions. Six divergent inbred lines in drought tolerance were crossed in a diallel fashion. Inbreds (6), F1's (15) and checks (2) were evaluated in the field for two seasons under two irrigation regimes, i.e. well watering (WW) and water stress (WS) via withholding the 4th and 5th irrigations to induce water stress at flowering stage. A split plot design in randomized complete blocks arrangement with three replications was used. Data analyzed across two seasons revealed that significant reduction in grain yield of maize (25.53%) due to water stress was accompanied with significant reductions in ears/plant (2.76%), 100-kernel weight (8.41%), rows/ear (4.23%), kernels/row (6.82%), kernels/plant (12.57%) and plant height (4.37%) and increases in days to silking (3.50%), anthesis silking interval (21.17%), barren stalks (26.18%) and leaf angle (9.41%). Interaction between genotypes and irrigation treatments was significant, indicating that selection is possible to be practiced under a specific irrigation treatment. Reduction in grain yield and its components due to water stress differed from genotype to genotype. The inbreds L20, L53 and Sk5, and the F1 crosses L20 × L53, L53 × Sk5 and L53× Sd7 were the most drought tolerant and highest yielders under WS and the WW environments. Mean grain yield/acre (GYPA) of drought tolerant (T) was greater than sensitive (S) inbreds and crosses by 170.18 and 54.73%, respectively under water stress (WS) conditions. Under water stress, T×T crosses were generally superior in most studied characters over T×S and S×S crosses, indicating that the most tolerant cross to water stress should include two tolerant parents and assures that water stress tolerance trait is quantitative in nature.