(43(1):1-16)Rice Varietal Difference in Characteristics Related to Dry Matter Production in Different Environment.

本試驗以稉秈稻各十五個品種為材料，分別於臺北及臺中進行兩期作之田間試驗，並於孕稉期、抽稉期、乳熟期及糊熟期取樣，測定葉片氮素濃度、葉面積及總乾物重，並求葉面積指數（LAI）、葉面積持續期（LAD）、作物生長速率（CGR）及淨同化率（NAR）。目的在瞭解水稻品種於不同期作或地區間，對於乾物質生產性狀之表現狀況，及其品種間之差異，以明瞭二期作低產的要因，所得試驗資料，俾供育種及栽培之參考。 試驗期間之氣象條件，第一期作移植期之低氣溫、低日射量至收穫期之高氣溫、高日射量，第二期作恰好相反，即由初期之高氣溫、高日射量變成末期之低氣溫及低日射量，而臺中地區兩期作之日夜溫差大於臺北地區，並且除了一期作收穫期之外，臺中地區之日射量皆高於臺北地區。 由試驗結果得知，秈稉型品種第一期作之總乾物重、LAD及CGR高於第二期作，又臺中大於臺北地區。這些乾物質生產性狀與產量呈現顯著性之正相關，並出現期作間或地區間之差異，及品種間差異大部份達1％水準的顯著性差異。 不論期作或地區皆表現高產，臺農67號、臺南5號、臺東29號、臺中秈10號及嘉農秈11號等品種，這些高產品種具有較高的總乾物重、LAD、CGR，並且乾物質生產性狀（乾物重、LAD、CGR）之期作間、地區間亦出現正的品種相關係數，這表示對不同環境有穩定性之表現，因此以總乾物重、LAD及CGR可當為育成高產品種選拔指標。Fifteen japonica and 15 indica rice cultivars were grown in the field for two crop seasons both in Taipei and Taichung. Samples were taken at 4 different growth stages (booting, heading, milky and dough stage) during each season to obtain data of leaf atea index (LAI), leaf area duration (LAD), leaf N concentration, the amount of dry matter accumulated (DMA), crop growth rate (CGR), and net assimilation rate (NAR). It is aim to elucidate the differences in the dry matter production of rice cultivars between the first and second rice crop grown in Taipei and Taichung area, in order to clarify the causes of low yield of the second crop. Information derived from this study should be of value as indices for future varietal improvement in rice. The second crop was under environments of high temperature and high solar radiation first and then markedly to lower temperature and lower solar radiation at harvest. But the changes of climatic factors of the first crop was in reverse trend. The day/night temperature difference in Taichung was larger than that in Taipei, while the solar radiation in Taichung was also higher than Taipei except the month of July. Experimental results indicated that generally DMA, LAD and CGR were higher for the first crop than for the second crop, and higher in Taichung area than in Taipei area. These characteristics showed a significant positive correlation with yield, suggesting that the sufficient DMA, LAD and CGR could increase the grown yield. They were all significant at 1% level when the comparisons were made among varieties, and between crop seasons, and between areas. Five varieties, namely Tainung 67, Tainan 5, Taitung 29, Taichung sen 10 and Chianung sen 11 yielded better than other varieties regardless of location and crop season. They all had higher values of DMA, LAD and CGR. And the positive correlation existed between crop seasons and between locations for those characteristics. The characteristics of DMA, LAD and CGR can be used as the selected marker for the varieties of high yield potential