EVALUATION OF COTTON (GOSSYPIUM SPP.) GERMPLASM FOR HEAT TOLERANCE UNDER NORMAL AND LATE PLANTING TIME

The objective of this study was to determine cotton (Gossypium ssp.) germplasm for heat tolerance under normal and late planting time. For this aiming 200 cotton genotypes and five check varieties (Gloria, SG 125, Flash, Ozbek 105 and Candia) were evaluated under two different temperature regimes and experiments were conducted according to the augmented design with four blocks. Field studies were carried out at the GAP International Agricultural Research and Training Center’s experimental area in Diyarbakır, Turkey, in 2016 cotton growing season. In the study heat susceptibility index was used for discriminate to the genotypes for heat tolerance. Genotypes were classified into four groups based on the heat susceptibility index. The results of this study indicated that five cotton genotypes (TAM 139-17 ELS, CIM-240, Haridost, MNH-990 and AzGR-11835) were in highly heat tolerant, 28 genotypes were found heat tolerant, 56 genotypes were in the moderately heat tolerant and other 120 genotypes were observed susceptible for heat tolerance. Based on the heat susceptibility index, five cotton genotypes can be used as parent for heat tolerance improvement in the cotton breeding program where high temperature is a limiting factor for seed cotton yield.