Evaluation of Hot Pepper (Capsicum annuum L.) Genotypes for Heat Tolerance during Reproductive Phase

Eleven hot pepper genotypes (viz., Sel-11, PLS-1, Sel-Dev, DCL-524, Punjab Surkh, VR-16, Pepsi-17-2, MS-12, S-217621, PBC-535 and Faslima) were evaluated for heat tolerance during summer 2011 to identify the most appropriate genotypes under agro-climatic conditions of Punjab.High temperature (40/24 °C, day/night) decreased fruit set in all the test genotypes with overall mean of 18.2% against 65.0% fruit set at optimum temperature (34/16 °C, day/night).High temperature also caused significant reduction in pollen viability, seed number fruit -1 , fruit length and fruit diameter.Heat susceptibility index (HSI) was used to measure heat stress tolerance of hot pepper germplasm for identifying genotypes exhibiting least reduction in fruit set percentage, pollen viability, seed number fruit -1 , fruit length and fruit diameter due to high temperature.On the basis of HSI for fruit set, only one genotype Pepsi-17-2 was classified as highly heat tolerant (HSI<0.5).Four genotypes namely DCL-524, VR-16, MS-12 and S-217621 were classified as moderately heat tolerant, showing HSI between 0.5 and 1.0.These five genotypes viz., Pepsi-17-2, DCL524, VR-16, MS-12 and S-217621 are most promising to initiate hybrid breeding program for the development of heat tolerant cultivars of chilli as maintenance of fruit set under high temperature is the most desirable character.