- 作者： 高景輝
- 作者服務機構： 國立臺灣大學農藝學系
- 中文摘要： 本研究主要之目的是瞭解不同器官對水稻幼苗葉片老化之重要性。臺中在來一號水稻幼苗種植於人工氣候室（日溫30℃，夜溫25，光照?自然光照）九天或十四天。水稻幼苗係以水耕栽培。?隔三天換營養液（Johnson氏之改良營養液）一次。 與生長九天之完整幼苗比較，根系切除可促進第三完全葉之葉片老化。'不論切除種子根或不定根或全部根均可促進葉片 老化。benzyladenine濃度?10-4M時可取代種子根，或不定根或全部根而阻止葉片老化。 水稻幼苗培養於營養液中可延緩葉片老化，營養液本身似乎具有延緩老化之功能。 胚乳（包括穀殼）切除亦可促進完全第三完全葉之葉片老化，此種促進效應可以被benzyladenine或蔗糖、或果糖或葡萄糖所抑制。水稻幼苗葉片之老化似乎與能量之正常代謝有關。 以十四天之幼苗?試驗材料發現當第四完全葉以下之葉片切除時可延緩第四完全葉之葉片老化。同時切除第四完整葉亦 可延緩第三完全葉之葉片老化。葉片間之彼此競爭根部之cytokinins或者胚乳內之cytokinins與可溶性糖類似乎在水稻幼苗葉片老化佔很重要之角色。 由上述結果可以瞭解水稻幼苗之葉片老化受器官間複雜之交感作用所控制。其中部份之交感作用是由根部所含之cytokinins所引起。
- 英文摘要： The inter-organ control of leaf senescence of rice seedlings was investigated. Compared with 9-day-old seedlings, the senescence of the third leaf is promoted by the removal of the root system. Both seminal root and adventitious roots play important role in regulating the senescence of the third leaf. Benzyladenine at optimal concentration (10~4M) completely replaces seminal root, or adventitious roots, or all roots in preventing the senescence of the third leaf. The addition of nutrient solution to rice seedlings is shown to delay the senescence of the third leaf. It seems that nutrients per se play some role in regulating leaf senescence. Endosperm removal accelerates senescence of the third leaf. This effect is completely reversed by the addition of benzyladenine, or sucrose, or glucose, or fructose. It is possible that normal energy metabolism is required for delaying leaf senescence. For 14-day-old seedlings, the senescence of the fourth leaf is significantly delayed by removing leaves below the fourth leaf. Similarly, the senescence of the third leaf is delayed if the fourth leaf is removed. Competition among leaves for root cytokinins or soluble carbohydrates and cytokinins in the endosperm also seems to play important role in the control of leaf senescence. In conclusion, the onset of leaf senescence of rice seedlings is seen to be a complex interaction between organs of the plant, a part of this interaction being mediated by cytokinins of root origin.
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