• 作者： 魏夢麗；沈美珍；陳建山；劉大江
• 作者服務機構： 臺灣省農業試驗所農藝系
• 中文摘要： 於水稻抽穗期與成熟期分析分??不同器官（葉片、葉鞘、莖與穗）乾物質、全氮與非構造性碳水化合物（TNC) 含量的變化，以確定不同期作水稻的?量限制因子。在穀粒充實時期，一期作稻生?乾物質與TNC之能力遠較二期作 ?高，並可吸收較多之氮素。成熟期之稻?佔有全分?55%之乾重，70%之全氮與85-95%之TNC含量，顯示有 多量物質轉移至發育中之穀粒。假設TNC之轉移效率?70%，則一期作水稻於抽?前貯存於營養器官中之TNC可 供應?部10-20%之需要，二期作?25-30%°—期作水稻之?量限制因子?貯蓄（sink)容積，如能增加一穗穎花數 或穀粒之體積，?量有再提高20%之可能；二期作水稻則貯蓄容積與供源（source)能力並?限制因子，欲求增產較 ?困難。
• 英文摘要： Amounts of dry matter, total nitrogen and total nonstructural carbohydrates (TNC) in the leaf blade, leaf sheath, stem and panicle of rice tillers were analyzed. The purpose was to investigate the balance between supply and demand of n and TNC during grain-filling. No difference in dry matter production prior to heading was found between the first and second rice crops in Taiwan. However, the first crop produced about 50% more dry matter and TNC than the second crop during the grain-filling period. Marked depletion of n from vegetative organs and deposition into panicles were also recorded. Panicles at maturity contained about 55% of total dry weight, 70% of total n and 85-95% of TNC of the whole tiller, indicating significant degree of retranslocation to the developing grains. Pre-heading storage of TNC contributed 10-20% and 25-30% of panicle TNC for the first and second crops, respectively, if the translocation efficiency was presumed at 70%. It was suggested that yield increase up to 20% was possible for the first crop rice if the sink size could be enlarged by increasing the spikelet number or grain volume. On the , contrary, yield increase of the second crop rice, limited by both sink size and source capacity, was difficult in terms of dry matter and TNC production and their distribution.
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