VARIATIONS AMONG MAIZE (Zea mays L.) HYBRIDS IN RESPONSE TO HEAT STRESS: HYBRIDS SELECTION CRITERIA

High ambient temperature is one of the most alarming climatic factors in challenging the productivity and sustainability of crops worldwide. An effective way to cope this problem is the development of climate smart, heat resilient maize hybrids through evaluating the cultivated germplasm. The main objective of current study was to evaluate local and multinational maize hybrids for their performance under optimal and heat stress conditions and to devise a selection criterion for the identification of heat tolerant maize hybrids. Nine maize hybrids, including local and multinational, were evaluated under optimal and heat stress conditions across three consecutive spring seasons (2017-18, 2018-19 and 2019-20) at Maize and Millets Research Institute, Yusafwala, Sahiwal. Results revealed the presence of highly significant differences among maize hybrids under both conditions and for all three seasons. Kernel yield was found to be highly correlated with net photosynthetic rate (0.735**), shelling percentage (0.910**) and relative cell injury percentage (-0.775**) under stress conditions. Cluster and biplot analysis unveiled that two local maize hybrids YH-5507 and YH-5427 were highly heat tolerant while multinational hybrids i.e. NK-8711, P-1543 and DK-6724 were highly productive under control/optimal conditions only. These hybrids can be invaluable sources of genes/alleles for the development of climate smart maize genotypes.