Morpho-physiological factors associated with grain yield of corn (Zea mays L.) under drought
1993
Alvarez, N.D.G.
The four corn genotypes used differed in their response to water stress treatment. Based on the drought index parameter, corn var XV4 and UPCA Var 1 were drought resistant while XVH5 and SUWAN 2 were drought susceptible. Kernel number was significantly reduced by water stress. Kernel number was the yield component which affected most the reduction in grain yield. The differences between genotypes' response to water stress was also related to differences in kernel number. The reduction in kernel number was associated with high % unfilled kernels especially at the tip section of the corn ear. Total leaf area per plant and dry matter production at post-flowering stage were strongly correlated with grain yield under drought. It was speculated that the ability of a plant to maintain high leaf area and produce high dry matter under drought enables a drought resistant plant to sustain kernel growth and development. Grain yield of corn was negatively correlated with anthesis-silking interval and positively correlated with the duration of pollen shed. Pollen viability was not affected by water stress treatment. Yield under drought seemed to be limited by factors in the female plant affecting silk viability or silk extrusion from the tip of the husk. The drought resistant varieties showed low leaf water potential, high leaf area, low shoot dry weight, high root: shoot ratio and high RLWC at seedling stage under condition of water stress. Under PEG-induced stress condition, drought resistant varieties also showed high root: shoot ratio. Among the screening techniques used to study drought resistance, the determination of root: shoot ratio during the seedling stage and rooting response of corn in PEG solution were shown to be the suitable ones for drought resistance
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