Evaluating the genetic diversity in maize hybrids under drought conditions using drought indices, SSR markers, and thermal imaging

Abstract

The aim of the study was screening fourteen hybrids of maize under normal and drought stress. A field trial was carried out during two summer seasons on an experimental farm, Ismailia, Egypt. Growth, yield physiological traits have been estimated. Indices of drought resistance were calculated for each hybrid; mean productivity, drought susceptibility index, tolerance index, geometric mean productivity and yield stability index. Simple sequence repeat analysis of DNA (SSR) was applied to estimate the genetic differentiation among the hybrids. Results showed that corn yields were significantly reduced during drought conditions. Maize hybrids exhibited significant differences for physiological and quantitative traits; plant height, number of leaves, ear height, ear diameter, ear length, relative water content (RWC) and chlorophyll content. In this study, the hybrids divided successfully into four groups according to their drought tolerance and yield production by using drought resistance indices. One of these groups; S.C128, S.C162, S.C167 and S.C176 hybrids had the highest yield under both conditions and more adaptive under drought stress. The results of the SSR analysis showed that polymorphism % was ranged from 50 to 67% with an average 58.5%, while polymorphism information content (PIC) values were ranged from 0.32 to 0.57. Genetic similarity coefficient values were ranged from 0.625 to 1.000 with an average of 0.8125. The study concluded that SSR analysis and drought indices results are quite similar. Thermal images were more effective for selecting maize hybrids for drought stress. Consequently; we recommended it to use in plant breeding experiment.