Studies on Screening of Maize (Zea mays L.) Hybrids under Drought Stress Conditions

Drought is one of the most serious problems posing a grave threat to cereals production including maize. Two experiments (lab and wire house) were conducted to screen out the most tolerant and most sensitive maize hybrids (7386, 6525, Hycorn, 9696, 32B33, 3672, MMRI and 31P41) under artificial imposing drought stress by PEG-6000 and under water stress applied after seedling emergence. In first experiment five water stress levels such as zero (control), -0.2 MPa, -0.4 MPa, -0.6 MPa, and -0.8 MPa were developed using polyethyleneglycol-6000 (PEG-6000) while in second experiment water stress applied after seedling emergence. Complete randomized design with three replications was used for both experiments at stress Physiological Lab, Department of Agronomy, University of Agriculture, Faisalabad, Pakistan. Promptness index, germination stress tolerance index (GSI), plant height stress index (PHSI), root length stress index (RLSI) and dry matter stress index (DMSI) were used to evaluate the genotypic response to PEG-induced water stress. In first experiment germination percentage, promptness index and germination stress tolerance index for all maize hybrids decreased with increasing artificial imposed water stress by PEG-6000. In second experiment on the basis of ranking the RLSI, PHSI and DMSI was observed in all maize hybrids. In both experiments the two maize hybrids 6525 and 32B33 showed that these are most tolerant against drought than all others maize hybrids while Hycorn and 31P41 maize hybrid showed that these are most sensitive against drought stress. The variation among hybrids for germination stress index (GSI) was found to be a reliable indicator of drought tolerance in maize.