Alteration of Water Relations and Yield of Corn Genotypes in Response to Drought Stress

The influence of drought stress on internal water status and the final grain yield of three Egyptian corn (Zea mays L.) genotypes; GIZA2, TWC310 and TWC320 at different developmental stages was investigated. Plants grown in pots were subjected to four levels of water stress at vegetative and tassel emergence stages. Exposure of plants to drought led to noticeable decreases in leaf water potential (Ψw), relative water content (RWC) and osmotic potential (Ψπ). Water stress changed the relation between leaf water potential and relative water content of all genotypes so that stressed plants had lower water potentials than control at the same leaf RWC. In all genotypes, stressed plants maintained osmotic potentials approximately – 0.47 MPa lower than controls. The declining Ψw and RWC were associated with lower stomatal conductance and photosynthetic rate. Data showed that tassel emergence stage was more sensitive to drought than vegetative stage where its corresponding grain yield was dramatically reduced. Genotype GIZA2 was the most drought-tolerant, among the tested corn genotypes, expressed in its high productivity under the simulated drought conditions.