抄録
Effect of day/night temperature on bud and flower abscission in pepper (Capsicum annuum L.) was studied using four varieties, ‘New Ace, ’ ‘Fushimi Amanaga, ’ ‘Thai Chilli’ and ‘Oriental Glory.’ Plants were grown in phytotrons with day/night temperatures 37/27, 32/22, 27/17°C under natural day light. Bud-abscission percentage increased with increasing the temperature especially in Thai Chilli, while no apparent relationship between temperature and flowerabscission percentage was observed, indicating flower buds were susceptible to high temperature. Also, the effect of different night temperatures (27, 22, 17°C with a constant day temperature of 37°C) and different day temperatures (37, 32, 27°C with a constant night temperature of 22°C) on bud and flower abscission of Thai Chilli was investigated, individually. In the former experiment, night temperature was found to have effect on only flower-abscission percentage. In the latter experiment, bud-abscission percentage increased with increasing day temperature.
The effect of two plant growth regulators on bud and flower abscission were examined using the var. New Ace and Thai Chilli under two day/night temperatures (37/27 and 27/17°C) . Application of maleic hydrazide (MH) and silver thiosulfate (STS) did not affect bud and flower abscission in New Ace. Mean while, application of vegetative growth inhibitor, MH, affected flower abscission in Thai Chilli.
These results indicate that, bud and flower abscission of peppers under high temperature might be caused by a hormonal mechanism, a failure in fertilization of the flower and competition for assimilates between bud and young leaves. Low night temperature and application of plant growth regulators might have an effect on the competition for assimilates, resulting in bud and flower abscission.
