從光合作用及轉流的觀點來看水稻高產株型

提高作物產量的兩個方向，一是提高光合同化能力，二乃將光合產物有效移轉到收穫部位。矮化是近代作物改良的主流，因為：（1）降低重心，抗倒伏；（2）莖稈的比率較低，分配到穀粒的光合產物會更多；（3）多施氮肥不易引起莖葉過度繁茂及倒伏，對榖實增產之效果好。但是廣泛被利用之缺GA矮性突變（sd1）株，其稈及葉都會縮短，使葉面積及葉片分布空間變小、擁擠，不利光合同化。為了改善此缺點，作者數十年前曾提出短稈長葉的株型，後續已成為選種的主流。一般的理解是：其穗在冠層內的位置較低，可降低重心及減少穗對葉片的遮光。但此株型尚有其他複雜的高產原因，較少為人所知。本文從光合供源（source）、穎花儲積（sink），以及抽穗時，貯存於稈及葉鞘內之非構造性碳水化合物（non-structural carbohydrates，NSC）之影響等三方面加以介紹。此外，目前水稻育種已朝大穗化，本文亦以葉片分布空間、醣花比（NSC／穎花）及稈的力學等方向加以探討。最後則說明秈稻之光合速率較稉稻為高，氣孔開度又大，有利於高溫適應。1973年，秈稻之高光合基因開始進入台灣稉稻中，且能表現高產，可謂開啟國內稉稻育種之新篇章。

關鍵字

水稻；光合作用；轉流；高產；株型；稈長；葉長；非構造性碳水化合物

並列摘要

There are two directions to improve crop yield, one is to improve the photosynthetic capacity, and the other effectively transfer photosynthetic products to the harvesting organs. Dwarfing is one of the major breeding objectives of modern crop improvement, due to: (1) resist lodging, (2) more photosynthetic products distribute to grains, and (3) high nitrogen use efficiency. However, the most widely used gibberellic acid-deficient dwarf mutation (sd1) is not conducive to photosynthesis because of its shortened culm and leaves, resulting in lower leaf area and leaf distribution space. To improve this defect, the author proposed the plant type with short culm and long leaves that have proven to be highly productive by recent breeders. Generally speaking, lower position of the panicle in the canopy reduce the center of gravity and the leaf shading, and more high-yield characteristics as well. This review confers the viewpoint of source supply, sink activity, and the effect of non-structural carbohydrates (NSC). In addition, current rice breeding programs have been focusing on large panicle, thus photo-assimilation, NSC, and the mechanics of culm were also discussed in this review. Higher stomatal opening and photosynthesis have been observed in Indica rice than those in Japonica rice, which is conducive to high temperature adaptation. Since 1973, photosynthesis gene of Indica rice has been introduced into Taiwanese Japonica rice, that increases high yield. After that, it initiates a new era for high-yielding Japonica rice breeding.

並列關鍵字

High-yield ； Culm length ； Leaf length ； NSC ； Rice ； Plant type ； Photosynthesis ； Translocation

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