Horticultural Science and Technology 원예과학기술지 ISSN:1226-8763(Print) 2465-8588(Online)

We investigated the effects of temperature cut-offs during the cold season on chlorophyll fluorescence response, shoot growth, flowering, and fruit development in passion fruit (Passiflora edulis var. edulis Sims.) to determine the temperature required for cultivation and develop a management system to help lower heating costs on Jeju Island, South Korea. When the temperature was cut-off above 5°C, the fluorescent density increased in steps O and J of the OJIP transient curve, but decreased in step P. Under identical temperature cut-off conditions, the photochemical efficiency of photosystem II (F_v/F_m) was low but the initial fluorescence (F_o) was high, which suggests that passion fruit plants were stressed at a temperature range of 5-10°C. The length and thickness of young secondary shoots and number of fruits per secondary shoot were great with rising the cut-off temperature, suggesting that passion fruit growth was satisfactory under a temperature cut-off of 10°C or higher. The fruit yield decreased due to reduction in the number of flowers per secondary shoot, while the flowering and harvesting dates advanced by 25-30 days and 41-43 days, respectively, under a temperature cut-off of 5°C. The size and weight of fruits decreased slightly, and the titratable acidity and fruit firmness were lower in plants grown at a temperature cut-off of 5°C compared to a cut-off of 10°C or 15°C. Moreover, fruit skin color changed from green to reddish purple earlier on plants grown at a temperature cut-off of 10°C or 15°C compared to a cut-off of 5°C. Therefore, 10°C or 15°C may represent the most appropriate temperature cut-off for passion fruit cultivation with respect to their vegetative growth, fruit quality, and fruit yield. Moreover, a temperature cut-off of 10°C could reduce heating costs in plastic greenhouses during the cold season.