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標題: 根溫處理對葉萵苣生理之影響
Effect of Root-zone Temperature on the Physiology of Leaf Lettuce (Lactuca sativa L.)
作者: 莊乃穎
Juang, Nae Yiing
關鍵字: Lettuce
Root-zone temperature
Electrolyte leakage
Water potential
出版社: 園藝學系
摘要: 夏季高氣溫及高根溫逆境是蔬菜露地與設施水耕生產的主要限制因子。本 試驗以涼季蔬菜之萵苣葉片為材料,經 50℃水浴5至60分鐘。測定17種萵 苣品系之葉片細胞膜的熱穩定性,以10分鐘處理者較能區分品系間熱傷害 之差異,篩選出熱傷害比率低者(青葉改良)與高者(白粉)二品系進行 25℃、30℃ 及 35℃ 之根溫處理 12 天,探討其生長與生理之變化。 在生長量之測定結果顯示,此二品系萵苣其根長、株高、葉面積、地上部 和根部鮮重及乾重於 25℃、30℃ 根溫處理間,大多無顯著差異;35℃時 此二品系的生長量明顯較 25℃ 或 30℃ 者為低。30℃ 高根溫下白粉品 系的生長量受高溫抑制之比率大多較青葉改良品系為大。 在生理測試方面,二品系根溫處理第 6天、12天之光合作用及之水分潛勢 ,於35℃時均顯著低於 25℃、30℃。35℃ 根溫下,地上部及根部之呼吸 率及根部活性較25℃、30℃為高,雖然部分無顯著差異。高根溫下呼吸率 提高可能是維生呼吸增加,因而造成根部可溶性碳水化合物增加。根部之 游離胺基酸含量、過氧化酵素及乙烯釋放率,於35℃高根溫下較25℃、30 ℃為高,顯示高根溫可能導致根部老化,進而抑制植株生長.
The thermostability of leaf-tissue membrane of seventen lettuce cultivars grown in a greenhouse was assessed by measuring electrolyte leakage of the tissue for specific intervals during a 60 minute period at 50℃ . Results indicated that the differential responses among cultivars, exhibited at 50℃ for 10 minutes , were most significant and were selected for the subsequent assessment of leaf-tissue heat injury.Among the cultivars tested , Improved Green Leaf (IGL) was found to be the most heat tolerant while White Power (WP) was the most heat sensitive . Two cultivars of lettuce , IGL and WP, were used to investigate the physiological changes and growth rates in solution at 25, 30, and 35℃. Results showed that the growth of both shoot and root were reduced by supraoptimal temperature of 35℃. The growth inhibition were more pronounced on WP than IGL at 35℃ root-zone temperature. The photosynthetic rate and water potential of the leaves were found to decrease with rising root-zone temperature up to 35℃. No significant differences in chlorophyll levels were observed among treatments. Increasing root temperature resulted in higher respiration rate and activity of roots . The respiration rate and activity of excised root were markedly enhanced as the root-zone temperature was raised to 35℃ and thus leading to more carbohydrate consumption in the root. This, in turn ,increased the export of sugar from shoot, and soluble carbohydrate accumulated in the root. The contents of free amino acids, the activity of peroxidase and the production of ethylene were increased significantly by exposing to 35℃ root-ozone temperature. The result indicated that the supraoptimal root temperature may induced the root senescence leading to inhibition of shoot growth.
Appears in Collections:園藝學系



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