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標題: 氣溫對茂木枇杷開花及著果之影響
Effects of Air Temperature on Flowering and Fruiting in Loquat cv. "Mozi"
作者: 邱禮弘
Chiu, Li-Hung
關鍵字: air temperature
出版社: 園藝學系
摘要: 本省枇杷8、9月之早花無法順利著果,且花粉活力差,若經以冷凍貯藏過 而仍有良好活力的花粉,來進行早花人工授粉試驗;其著果率可達15∼20 %,與一般正常盛花期的自然著果率相似,因而可推知早花不著果之障礙 因子與雄蕊的花粉活力有密切關係。由田間取樣調查之花粉產量與發芽率 都隨花穗發育時間(日期)的增加而呈現正相關,而枇杷花穗發育期為9 ∼12月,時序是逐漸轉涼,因而推知枇杷花粉活力表現與氣溫變化有關; 因此利用花蕾期人工變溫處理,得知最適於本省枇杷花穗發育之溫度範圍 為18∼23℃,而25℃以上之溫度則不利其花粉活力表現。以每日有4小時 的34℃高溫處理5天,即可使12月盛花期的高度花粉活力(約90%)降至如 同9月早期花之不良活力(約30%)並且經此高溫,易使花粉管破裂、胞質 外溢;而如以9月早期花穗經瓶養在18℃涼溫下,經5天處理,即可擁有較 佳活力(約52%),經此更可證實氣溫對枇杷花粉活力的影響深遠。基於上 述緣由,利用早期花的遮光降溫處理,調查其著果情形,可得知遮光降溫 的效應在地表與植體溫度的表現,尤其是葉片與花器的表面溫度。在9-10 月的晴朗白天日照下,若不經遮光處理往往植體溫度會超過34℃以上,這 對此時原本活力不佳的花粉,更加重高溫逆境的障礙。因此可利用早期花 的遮光降溫來改善著果情形,使產期提早,而且有助果品提升本試驗經由 早花人工授粉、蕾期人工變溫處理、早期花遮光降溫處理等三方面的探討 ,證實氣溫是影響枇杷花粉活力表現的限制因子。
The early-season flower buds of loquat formed during August and September in Southern Taiwan usually fail to set due to relatively poor pollen viability. Hand pollination with viable pollen grains after cold storage produced 15 to 20% fruit set comparable to that under natural condition. Field sampling indicated that pollen yield and rate of germination of loquat increased with the development of inflorescence from September to December. The positive correlation between viability and cold weather led us to predict that the two processes are closely related. Results of temperature regulation experiment showed that the optimal temperature for the development of loquat inflorescence ranged from 18°to 23℃. Temperature above 25℃ were found to be unfavorable. A 4-hour treatment at 34℃ daily for a period of 5 days reduced the highly vital pollen (produced in December with germinating rate of 90%) to the level of viability of these produced in September (30% germinated). Besides, damaged pollen tubes, plasmoptysis were common place among pollens after high-temperature treatment. A measurement of plant tissue temperature especially leaves and flowers in September and October revealed that unshaded floral parts could reach 34℃ midday might have adverse effect on pollen viability. Lowering air temperatkure by shading not only would successfully bring about early-season fruit production ,but also enhanced fruit quality. Data obtained with hand pollination, temperature regulation and early-season shading in this experiment suggest tentatively that air temperature is the limiting factor for the control of pollen viability and successful fruit set of loquat in Taiwan.
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