In vitro response of maize (Zea mays L.) hybrids to polyethylene glycol induced drought using the slanting plate technique

Maize is an important cereal crop of the world and in India, it is grown in the rainy and post-rainy seasons. In the rainy season, among other stresses affecting the maize productivity, drought is significant under a changed climatic scenario. Although maize is sensitive to drought at all growth stages, drought at the seedling stage results in a poor crop stand and establishment, significantly impacting productivity. Identifying moisture-stress tolerant maize inbred lines for seedling stage drought situations and using those in developing drought-tolerant hybrids play a pivotal role in increasing maize yield. In this study, a set of hybrids derived from tolerant and susceptible inbreds was studied for their response under in vitro seedling drought induced by polyethylene glycol, employing the slanting plate technique. Substantial variability among different polyethylene glycol levels (0, 10 and 20 %), maize hybrids and interaction between polyethylene glycol levels and maize hybrids was observed for germination and seedling traits, indicating differential response of the maize hybrids. Higher genetic advance with higher heritability was observed for root and shoot length, indicating the preponderance of additive gene action governing these traits. It was interesting to note that the germination ability of seeds was significantly reduced in all hybrids at 20 % polyethylene glycol, following poor seedling vigour that was reflected in diminished expression of seedling traits. The hybrids, GPM 114 × CML 451 and GPM 114 × CAL 1426-2, involving seedling drought-tolerant parents, showed lesser reduction for root length, suggesting these drought-tolerant lines can be used as donors for the development of seedling drought-tolerant hybrids suitable for cultivation in rainfed eco-systems. It is evident from the present study that screening maize genotypes at 20 % polyethylene glycol would help in identifying reliable genotypes for seedling drought tolerance.