溫度及乾旱對荔枝開花的影響

Effects of Temperature and Water Stress on Flowering of Litchi (Litchi chinensis Sonn.)

本試驗以’糯米糍’荔枝高壓苗為材料，探討溫度及乾旱處理對荔枝開花的影響。試驗分成兩部分，第一部分，控制溫度為25／20°C，20／15°C，15／13°CC（日／夜溫），乾旱處理為循環式乾旱至葉片水分潛勢-3.0MPa，兩循環，試驗於民國84年10月6日開始進行，溫度處理期間為15週，乾旱處理期間於25／20°C為6週，20／15°C及15／13°C約8～9週。第二部分於戶外進行，乾早處理為循環式乾旱至土壤水分張力-70～-80Cb，七循環，試驗期間為民國84年10月11日至12月9日。試驗結果顯示，15／13°C處理7週，可促進’糯米糍’荔枝開花，25／20°C、20／15°C處理則無法開花；戶外處理結果顯示，秋末冬初灌水會引起持續抽梢無法開花，乾旱處理雖抑制抽稍，但復水後卻僅極少數枝條開花，大多數枝條仍然抽梢而無法開花。本試驗顯示溫度為控制荔枝開花的重要環境因子，而若無低溫配合，僅是乾旱處理並無促進開花的效果。

The combinations of temperature and severe cyclical water stress (-3.0Mpa, predawn) treatments were conducted on 2 years old 'No Mai Tsz' litchi (Litchi chinensis Sonn.) plants in order to define conditions needed to induce flowering.. The duration was 15 weeks for temperature treatments and 6-9 weeks for water stress treatments. At 25°C /20°C(day/night) temperature, irrigation promoted vegetative growth, water stress treatments unable flush and after rewatering no panicles were produced. At 20°C/15°C(day/night) temperature both irrigation and water stress treatments prevented vegetative growth and panicle appearance. Both 15°C/13°C(day/night) temperature treatments for 7 weeks induced the development of visible panicles from terminal buds. Field cyclical water stress treatments (irrigation when soil water tension attained -70~ - 80 centibars) also conducted during October to early December on 2 years old 'No Mai Tsz' litchi plants. Only very few terminal buds developed panicles after rewatering and exposured to winter low temperature. Irrigation treatments promoted vegetative growth without any flowers. Water stress reduced vegetative growth but couldn't induce 'No Mai Tsz' litchi flowering.