(31(4):255-264)Cold Tolerance of Rice at Seedling Stage - I. The Reaction of Rice Varieties at Different Seedling Stages

Abstract

本試驗之目的是以植物生長箱檢驗不同苗齡對低溫之反應，並查不同類型水稻品種的耐寒性，以探尋可靠的檢定方法及了解各品種之耐寒性，俾供抗寒育種或有關試驗之參考。使用光照強度為270 Microeinsteins m-2Sec-1，而光照時問12 小時／天，以10℃之低溫處理秧苗9 天，並以秧苗存活率表示其耐寒性。試驗結果摘述如下： 將7 個稉稻品種，13 個秈稻品種共20 品種，每隔3 天播種一次，連續播10次，在低溫處理前，調查參試之20 品種各播種期的苗齡供參考，試驗結果稉稻較秈稻耐寒。參試品種中稉稻以USSR No.45，藤坂5 號，新竹糯4 號較耐寒、秈稻是以臺農秈育2414 及上杭大冬較耐寒。一般說4.5 葉齡的秧苗對低溫最敏感，而在3.5~4 葉齡時耐寒性品種間之差異最大。 以IR 29 與臺農67 號之正反交及其與臺農67 號同交之4 個F2集團在3.5 葉齡時，進行耐寒性檢定。結果，臺農67 號為耐寒品種，而IR29 對低溫極敏感，且臺農67 號之耐寒性主要受一對顯性遺傳因子控制。 以162 個水稻新品系在3~3.5 葉齡時，進行耐寒性檢定。結果只有10 個品系之存活率高於80%，而存活率在61~80%的亦只有3 品系，顯示新品系對低溫敏感，應於育種時引進耐寒基。 The main purpose of this experiment was to research the basic data for screening cold tolerant vaieties and breeding matherials of rice. A plant growth chamber was used to control the air temperature, which was set at 10°C for 9 days. The light intensity was 270 Microeinsteins m-2Sec-1for 12 hours per day. The experimental results were summarized as follows: Seven Japonica and thirteen Indica rice varieties were used for this experiment. All twenty varieties were planted ten times at 3 day intervals. The leaf age of each rice variety at each planting was recorded just before low temperature treatment. (see Table I) The results showed that Japonica rice varieties were more tolerant to low temperature than Indica rice varieties. Among the cold tolerant varieties, Fujisaka 5 and Hsinchu Waxy No. 4 are Japonica rice varieties, while Tainung Sen Yuh 2414 and Shang Hung-Ta-Dong are Indica. Based on the survival rate of seedlings, the most sensitive stage was at 4.5 leaf age, while the biggest varietial differences was at 3.5-4 leaf age. According to the basic information mentioned above, four F2 cross-combinations were used for screening the cold tolerant plants at 3.5 leaf age. The rate of survival plants of each F2 Population was recorded in Table 3. It showed that IR29 was a cold susceptible rice variety, and Tainung 67 was a cold tolerant variety. Based on the four F2 populations, cold tolerance of Tainung 67 was found to be governed by one pair of dominant genes. In addition, 162 rice strains were used for cold tolerant testing at 3-3.5 leaf age. Only 10 strain had a seedling survival rate higher then 80%. The results indicated that most of the breeding materials tested were cold susceptible. Therefore, we may conclude the cold tolerant genes should be transfered into the breeding program, especially for indica rice