Flowering Habit and Fruit Setting of Pointed Gourd (Trichosanthes dioica Roxb.) Influenced by Seasonal Temperatures

Pointed gourd (Trichosanthes dioica Roxb.) is a dioecious cucurbit vegetable and fruit is the main edible part. In this experiment, we elucidated the flowering time temperature variations effect on the flowering habit, fruit yield and pollen germination ability under glasshouse and open field conditions. The highest number of female flowers (32.3), harvested fruits (29.6) and fruit weight (53.3 g) were found in 16-30 June with average day/night temperature 27.1/23.9°C in the glasshouse cultivation. Though, the number of female flowers were high (24.0) in 1-15 August (30.8/27.5°C), but harvested fruits (13.6) and fruit weight (46.0 g) maximum in 1-15 July (29.1/26.7°C) and 16-30 June (25.2/22.2°C) in open field condition. On the other hand, the highest number of male flowers was produced in the glasshouse (51.6) and open field (35.0) during 16-31 July with different temperatures (34.2/29.9°C in glasshouse) and (31.6/27.9°C in open field). Results demonstrated that flowering habit of pointed gourd differed to a greater extent at high temperature than low temperature. Female flowering was accelerated up to a certain level of temperature (27-30°C) and after that decreased, whereas, higher temperature (more than 30°C) among the flowering time temperatures was found as favorable to increase male flowering regardless of growing conditions. Pollen germination rates were adversely affected due to high temperature and declined the fruit set rate and fruit yield in both growing conditions.