PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Climate change poses significant challenges to agricultural production, particularly in semi-arid and arid regions, characterised by high temperatures and frequent drought conditions. Choosing appropriate crop genotypes and effective agronomical management practices for tolerance to abiotic stress becomes crucial for sustaining crop productivity under these conditions. This experiment aimed to determine the effect of exogenous abscisic acid spraying (distilled water only, 9 and 12 ppm) as the main factor on the performance of four sorghum genotypes (Bohooth, Giza, Al-Khair, and Warkaa) as sub-factors by using a split-plot design in RCBD repeated thrice. The study results showed that the interaction of abscisic acid spray at 12 ppm with the Giza and Al-Khair genotypes outperformed the control, recording the highest averages in most of the sorghum morphological indices. The abscisic acid spray had a significant positive impact on the sorghum genotypes, significantly enhancing growth parameters and grain yield, especially at 12 ppm concentrations. These findings suggest that ABA spraying has a potential priming influence to enhance sorghum grain filling capacity under heat stress during the grain filling stage, particularly by inhibiting the reactive oxygen system and increasing starch synthetase activities in sorghum grain.