Effects of Different Day and Night Temperatures on Female Flower Formation in Zucchini

Abstract

The effect of several day and night temperature combinations on zucchini female flower formation was investigated in a temperature-controlled climate chamber under natural sunlight. The total number of flowers increased with higher night temperatures, but there was no difference in the number of female flowers and the length of the largest leaf. The ratio of female flowers to the total number of flowers was significantly lower at day/night 30°C/30°C than at 30°C/10°C and 30°C/20°C. The female flowering and fruit-setting rates were highest at 30°C/10°C and 30°C/20°C. Higher daytime temperatures (25°C/15°C and 35°C/15°C) increased the number of total flowers. These results indicate that female flower formation of zucchini was decreased by increasing the night temperature, and that both female flower blooming and fruit-setting were markedly inhibited at 30°C/30°C.Key Words：cultivar temperature, day and night temperature, female flower differentiation