Evaluation of Some Wheat (Triticum aestivum L.) Genotypes Under Terminal Heat Stress

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Mona Osman Mohamed Jaber
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University of Khartoum
Heat stress is one of the abiotic stresses that reduces the potential vegetative growth and productivity of wheat. This study aimed at estimating the amount of genetic variability for heat tolerance in wheat (Triticum aestivum L.) and the effect of heat stress on the growth and productivity of wheat using different sowing dates. Fifteen genotypes were grown at three different sowing dates, in two field consecutive seasons (2005/06 and 2006/07), at Shambat, Sudan. Three sowing dates' were used; namely; 15th of November, the recommended sowing date for wheat(S1), 14 days later than the recommended sowing date (S2) and 28 days later than the recommended sowing date (S3). Split–plot design was used with three replications. The correlation coefficients between yield, yield components and other vegetative traits were determined. The induced heat stress by delayed sowing dates was severe enough to cause significant variations, with slight effect of the second sowing date (S2). Significant differences among the fifteen genotypes were found for most of traits. The genetic variability was lower and non-significant under non–stress condition (S1) than under stress conditions (S2 and S3).The genotypes x year's interaction variance was significant under third sowing (S3) condition. Heritability estimates exhibited wide range of variation; the highest heritability and genetic advance was recorded for days to 50 % heading. The genetic variability was reduced with increase in heat severity when sowing date was delayed 28 days (S3). Some genotypes were slightly tolerant to heat stress, while others were highly tolerant under severe heat stress. Vegetative characters showed negative and non-significant correlation with each other in the two seasons. grain yield was positively and non-significantly correlated with number of kernels/plant, number of spikelets/spike, 100-kernels weight and number of kernels/spike in the first season, whereas in the second season, it was correlated positively and non-significantly with its all components, with exception of number of kernels/plant and number of kernels/spike. It could be concluded that the tested genotypes of wheat exhibited genetic variability for heat tolerance, indicating possibility of improving this character genetically
A thesis submitted to the University of Khartoum in partial fulfillment of the requirements for the degree of Master of Science (Agric.)
Wheat Triticum aestivum L. Heat stress Agronomy University of Khartoum
Mona Osman Mohamed Jaber, Evaluation of Some Wheat (Triticum aestivum L.) Genotypes Under Terminal Heat Stress. – Khartoum : University of Khartoum, 2009. - 162 P. : illus., 28 cm., M.Sc.