水稻抗紋枯病之研究 1．抗紋枯病之稻品種及其特性

Abstract

Sheath blight is one of the most important rice diseases in Taiwan. The infected acreage is about one quarter of the total rice area. However, no commercial rice variety showing resistance to the disease has been reported. The major way of controlling the disease, at the present, is chemical comtrol. Mon and Asozin have been widely used on the island. In fact, chemical control may cause environmental pollution, and increase the production cost. Therefore, the main purpose of this study is to search the resistant gene of the disease, for tranferring it into the commercial varieties. The preliminary results showed that no rice variety can prevent the infection of the fungi after inoculation, but the difference in disease symptom among the varieties at the later stage of growth are obvious. The relatively resistant varieties tended to have a taller plant height, and the semidwarf rice varieties tended to be more susceptible to the disease. Thus, it may take a risk to develop semidwarf rice variety without considering the disease resistance. Fortunately, a few semidwarf rice varieties with moderate resistance to sheath blight have been found in the test. It indicates that a semidwarf rice variety which is susceptible to sheath blight can be improved by transferring the resistant gene (s) into it, regardless of the plant height. Besides, the reactions of rice varieties to sheath blight and to brown planthopper are positively correlated. It showed that the rice varieties, which are susceptible to the brown planthopper, are more sensitive to sheath blight. Some other characters may affect the disease reaction, such as tillering number, plant type, and growth duration, do not included in this paper.