Genetic Diversity Analysis for Heat Stress Tolerance in Chili (Capsicum annum L.)

Abstract

Chili (Capsicum annuum L.) also known as hot pepper and red pepper is a valuable condiment all around the world. It holds significant importance in the global economy and is used in a variety of products such as sauces, pickles, medicines, and insect-repellent sprays. Pakistan is 4th largest chili producer worldwide. Global warming a is an important issue around the globe that causes losses to global agricultural productivity. In this study, chili germplasm was screened to identify heat-tolerant genotypes. The experiment was carried out following factorial under RCBD (randomized complete block design) having 785 with two treatments and three repeats. The genotypes were sown in nursery trays in November 2023 and transplanted in the field in February 2024. The data recording was performed twice. The data collected in March-April was considered as data from controlled treatment while data recorded during June-July was considered as heat-stressed treatment. The data was recorded for Days to flowering, NDVI value, plant height (cm), number of primary branches per plant, fruit length (cm), fruit diameter (cm), individual fruit weight (g), number of fruits per plant, fruit yield per plant, and pollen viability. Heat susceptibility indices for all traits were calculated. The data was subjected to analysis of variance, path coefficient, and biplot analysis. Genotypes D1, D4, D7, D12, 12, 42, 75, 76, 118, 172, 217, 229, 424, 497, 514, 532, and 772 are selected as heat tolerant genotypes because the yield of these genotypes was unaffected or slightly affected due to heat stress during the experiment, while on the other hand, the genotypes 41, 44, 57, 63, 94, 123, 141, 154, 285, 347, 516, 540, 601 and 663 are selected as heat susceptible because these genotypes have high heat susceptibility index and there was a huge decrease in the yield in heat-stressed condition as compared to non-stressed condition.