The inflorescence (spike) morphology greatly affects the wheat grain yield. The number of grains per spike is of the main yield components. However, some wheat varieties in heat-prone and drylands such as Sudan show grain shattering habits in which grains fall to the ground when harvesting is delayed. This results in a yield loss of up to 30%, hence the development of non-shattering varieties is urgently required. Therefore, this study aims to elucidate the mechanism of grain shattering and identify molecular markers for the efficient development of non-shattering varieties. Evaluation of spike morphology under high-temperature growing conditions revealed that the awns curved horizontally, resulting in the opening of the lemma and palea. The relationship between the degree of shattering and the curvature of the awns was re-examined under field and controlled growth chamber conditions. Under both conditions, the cultivars with curved awns at the maturity stage have a high degree of shattering habit. A wheat core collection comprising 190 lines was investigated for their awn phenotypes under field conditions. A genome-wide association study (GWAS) revealed significant marker-trait associations in multiple chromosomal regions. Based on these results, we plan to proceed with QTL analysis in a segregating population and develop markers that can be used for DNA marker-assisted selection. The introduction of non-shattering varieties is expected to improve yield and reduce losses, leading to sustainable wheat production in the heat-stressed drylands.