Effect of Supra-optimal Temperature on Seed Germination of Selected Sorghum Genotypes

Abstract

Sorghum (Sorghum bicolor) is the most important traditional cereal crops of the hotter and drier regions. Its production is however affected by both abiotic and biotic factors. Among abiotic factors heat stress caused by supra-optimal temperatures affect seed germination, which ultimately leads to yield loss. The objectives of this study were therefore to i) evaluate the impact of supra-optimal temperature on seed germination and ii) identify a sorghum genotype with a highest resilience to germinate under heat-stressed condition. To achieve this objectives four popular sorghum genotypes Kuyuma, Sima, Vumba and ZSV 36R were tested  and planted following a completely randomised design (CRD) replicated three times under two experimental temperature regime of 25^o  (Optimum) and 37^oC (Supra-optimal). Data was collected on normal seedlings, abnormal seedlings, root length and shoot length. Results showed significance differences between the grand mean responses for all measured parameters across genotypes in the two temperatures regimes (Paired t- test, P< 0.01). Abnormal seedlings counted was the most affected parameter under a supra-optimal temperature exposure exhibiting a percentage increase of 183.2%, when compared to the optimum temperature environment. The genotypes ZSV 36R was identified as the most resilient performing genotype under heat stress.