Corn is the most important cereal crop of the world. It is not only used as human food but also as industrial raw material and animal feed. The effect of warm temperatures on corn crop is a two-edged sword. It is a typical monoecious plant and more prone to the desiccating temperature. The degree of damage depends upon the intensity and duration of the heat spell. The results indicated that use of single plant trait as indirect selection criteria, would be unlikely to improve yield or heat resistance rather a harmonious combination of most or all of the traits will impart whole plant thermo-tolerant abilities in a single genotype.