Department of Horticulture, National Ilan University1
Department of Horticulture and Landscap Architecture, National Taiwan University2
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.
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