Scientists identified heat-tolerant maize hybrids by studying different traits under heat stress conditions. They found that certain morphological traits were affected by heat stress, and grain yield was positively correlated with specific stress-tolerant indices. One particular double haploid line, DH_1_178, was identified as heat tolerant due to its high grain yield in both optimal and heat stress conditions. This line could be used in future breeding programs to develop maize varieties that can withstand high temperatures and produce good yields.