Heat Stress Tolerance Indices and Their Contribution in Identifying Heat Tolerant Bottle Gourd [Lagenaria siceraria (Molina) Standl.] Genotypes

Bottle gourd, a popular winter vegetable in Bangladesh, is experiencing a year-round increase in demand. High temperature stress disrupts physiological structure, fruit quality and crop yields, limiting the year-round cultivation of bottle gourd. The research aimed to identify heat stress-tolerant genotypes to extend growing seasons and increase production among varieties and breeding materials.

The study conducted at Vegetable Research Center, Dinajpur of BRAC Seed and Agro Enterprise, Bangladesh consisting 58 bottle gourd genotypes under normal and heat stress conditions using augmented block design. Meteorological data showed heat stress resulted ~5-7°C higher air temperatures than normal sowing environments.

Heat stress tolerance indices indicated that the genotypes with a combination of greater values of MP, GMP, HM, YI and STI and lower values of SSI and TOL are high performed and productive breeding material. Yield based stress indices SSI and TOL had a negative association with fruit yield under heat stress (Ys), while strong positive correlations with STI, MP, GMP, HM and YI. The cluster analysis classified bottle gourd genotypes as tolerant, medium tolerant and susceptible to heat stress. Heat stress tolerance indices could be effective tools for identifying heat tolerant bottle gourd genotypes in field. The genotypes BG-45, BG-02, BG-57, BG- 39 and BG-43 determined as high performing and stable breeding material under both normal and heat stress environments and might potentially be employed in future breeding programs.