Reproductive response based diversity in genetically distant maize (Zea mays L.) germplasm under heat stress

Abstract

Maize (Zea mays L.) is third main cereal after wheat and rice. It is grown across the world. Maize yield is affected by different stresses. Among these, high temperature is the major one in reducing the yi eld. High temperature influences the reproductive stage of spring crop in Pakistan. So there is a need to study the reproductive responses of genetically diverse germplasm under high temperature. Total 11 hybrids of maize were tested using randomized complete block design. Data were recorded on pollen germination percentage, pollen grain size, pollen tube length, leaf temperature, cell membrane thermostability, leaf chlorophyll content, cob length, cob diameter, number of rows per cob, number of grains per row, 100 grain weight and grain yield per plant. The dat a were analyzed statistically to study the correlation and path coefficient. The analysis of variance showed that all the genotypes were significantly different from each other for all the above param eters. Highly significant results showed that there was a strong variability present in the genotypes. The grain yield per plant had positive and significant correlation with pollen germination percentage, pollen grain size, pollen tube length, leaf chloro phyll contents, cob length, cob diameter, number of kernels per row and 100 grain weight. It had significantly negative correlation with leaf temperature and cell membrane thermostability which was expressed as relative cell injury percentage. Path coefficient analysis showed that pollen germination percentage, pollen grain size, cell membrane thermostability, cob diameter and 100 grain weight had positive direct effects on grain yield. Pollen tube length, leaf temperature, leaf chlorophyll contents, cob le ngth, number of rows per cob and number of grains per row had negative direct effects on yield per plant. 100 grain weight had the highest positive direct effect on grain yield. So, it can be used as selection criteria for yield improvement.

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