(62(3):195–208)Drought Tolerant Rice Lines by Screening an IR64’ Mutant Stock

本研究利用經二次疊氮化鈉突變誘發所培育之IR64’ 誘變庫為材料，於水稻幼苗期利用28% PEG 6000 模擬缺水逆境之水耕液栽培方式，由2,500 個突變體迅速篩選出152 個耐旱突變品系，其後再利用水旱田栽培方式進行突變品系成株期耐旱性之評估，試驗結果顯示有58.7%之突變品系其產量耐旱指數 (水田產量/旱田產量百分比)表現較佳，具有耐缺水逆境之潛力；進一步以9 個突變品系進行成株期耐旱性的評估，結果發現各突變品系在產量與耐旱等級之表現趨勢一致，並以SM47 及SM100 兩突變品系的耐旱特性表現最佳。由試驗結果可知水稻耐旱育種之操作可在幼苗期先透過PEG 6000 進行缺水耐受性的篩選，其後再透過產量耐旱指數進行篩選，如此便可快速選育出適合台灣栽培利用之耐旱水稻新品種。 Breeding new rice varieties with drought tolerance is one of important topics of modern breeding programs. In this study, we screened mutant lines of drought tolerance from a mutant stock of IR64’ which was a widely cultivated cultivar in the world, and induced by sodium azide twice. A total of 152 mutant lines of drought tolerance out of 2,500 mutants were selected by using PEG 6000 to mimic water deficiency during the seedling stage. Consequently, the mutant lines of drought tolerance were evaluated grain yield harvested from paddy and upland cultivations. The yield indices were used to assess drought tolerance of each mutant line. As a result, up to 58.7% of mutant lines performed good potential for drought tolerance according to its index of yield drought-tolerance (the percentage of yields of paddy cultivation/upland cultivation). However, the nine mutant lines rated as scale 3 of drought tolerance at the seedling stage were assessed drought tolerance for multiple experimental field trials at the adult stage. The results revealed that all mutants exhibited same trend in yield and drought tolerance, and two mutant lines, SM47 and SM100, had the best performance. This study demonstrated the strategy of rice breeding for drought tolerance: first, screening drought tolerant lines by treatment of PEG 6000 during the seedling stage to exclude lots of materials with poor tolerance because of water deficiency; second, the selected lines were evaluated by the index of yield droughttolerance. Therefore, this strategy may help rice breeders to facilitate breeding of new drought tolerant rice varieties in Taiwan