Temperature Effects on Shoot Growth and Flowering of Kumquat Trees

This study investigated the effects of temperature on the shoot growth and flowering of potted kumquat [Fortunella margarita (Lour.)Swingle] trees grown in subtropical conditions of I-Lan County in Taiwan.Temperature treatments included T 25-32, T 17-25, T 22, and T 18.The T 25-32 treatment trees were to the day/night temperatures of 25/18°C for 2 weeks, followed by 28 weeks at 32/25°C.T 17-25 was exposed for 4 weeks to 17/10°C followed by 26 weeks at 25/18°C.T 22 and T 18 were exposed at 22/18°C and 18/13°C, respectively, for the entire duration of the experiment.Control trees were placed in a plastic greenhouse under conditions similar to the natural environment.The kumquat trees exposed to high-temperature environment of 32/25°C showed more frequent and speedy sprouting of new buds, but induced the earlier termination of shoot elongation growth, resulting in decreased vegetative growth.The temperature treatments lower than 22°C suppressed the new shoot production but increased the shoot growth period, resulting in increased shoot length and diameter.Temperatures higher than 25/18°C readily induced flowering, with flowering being advanced under the higher temperature conditions such as 32/25°C.However, flowering was substantially inhibited under temperature conditions lower than 22/18°C, indicating the negative role of relatively lower temperatures on flowering of kumquat trees.