Improvement of grain yield and vegetative characters of temperate maize (Zea mays L) over environments

Agricultural activities are nowadays facing water deficit as a result of climate change; hence, inclusion of tolerance in maize is necessary for high yield. Studies were conducted at Dirab Experimental Research Station, Saudi Arabia from 2009 to 2012 to select suitable lines. Six maize inbreds selected from maize germplasm of diverse sources were crossed in a half diallel method. 15 F-1 hybrids and two high yielding commercial varieties were evaluated under three water regimes using Randomized Complete Block Design (RCBD). Soil water deficit was created a week before tasselling and stopped before grain filling using Food and Agricultural Organization (FAO) evaporation pan as a guide with water applied at 50, 70, and 90 inches of water levels in the evaporation pan to create E1, E2, and E3 environments respectively. Wide diversity among maize genotypes and highly significant genotype by environment (GxE) interaction was recorded. Water deficit reduced plant height, leaf area and grain yield and increased leaf rolling. Grain yield of F-1 hybrids was higher than that of their parental lines, with P5xP6 given the highest value indicating the usefulness of these hybrids for improvement. Although midparent heterosis values were higher than that of better-parent (BPH) heterosis, but both varied with level of water supply, however, hybrids with KSU 8-33 (P3), KSU 4-58 (P4), KSU 6-47 (P5) and KSU 3-69 (P6) parental background showed highly significant heterosis for all the characters across the environments and could be considered for further improvement.