High temperature effects on development and floret sterility of diverse sorghum lines

Sorghum (Sorghum bicolor L. Moench) is grown as a dryland crop in semiarid subtropical and tropical environments where it is often exposed to high temperatures. The incidence of exposure to high temperature is likely to increase with global warming and climate change. High temperature can have significant effects on growth, development, and yield. Damaging effects on development of reproductive organs have been reported for sorghum. The objective of this study was to examine the effect of high temperature on pollen viability and seed-set and explore its genotypic variability. Eighteen diverse sorghum genotypes were grown at day/night temperatures of 32oC/21oC (optimum temperature, OT) and 38oC/21oC (high temperature, HT) in controlled environment chambers. HT significantly reduced pollen viability and seed-set percentage of all genotypes. Genotypes differed significantly in pollen viability percentage (17% to 63%) and seed-set percentage (7% to 65%). There was a strong and positive correlation between pollen viability and seed-set percentage (R2= 0.93, n=36, P<0.001), suggesting a causal association. The observed genetic variation in these traits could be exploited through breeding to develop heat tolerant varieties for future climates.