Journal of Taiwan Agricultural Research

Author:Lih-Jiuan Hsieh, Yih-Chang Chang and Ting-Fang Hsieh*

Abstract:

    The objectives of this study were to evaluate the susceptibility of rice cultivars at different growth stages to bacterial leaf blight of rice caused by Xanthomonas oryzae pv. oryzae by the leaf clipping inoculation method and to determine effects of clipping off leaves at different lengths and different positions on the disease reaction. The experiments were conducted at the second crop of 1994 and the first crop of 1995 in a greenhouse and in the Institute’s experimental field. Inoculation of plants at 30, 45 and 60 days after sowing (DAS), and at booting and heading stages of four rice varieties including two indica (Tainung sen 18, resistant and Tainung sen 3, susceptible) and two japonica (Tainung 61, resistant and Tainung 67, susceptible) rice showed that the 30 DAS stage was the most susceptible to infection of the bacterial pathogen in each variety. Except the heading stage, the inoculation at all growing stages could distinguish the resistant and susceptible varieties. This suggests that the result of resistant screening at 45 or 60 DAS stage was similar to that normally evaluated at the booting stage in Taiwan. At the heading stage, there was no significant difference in disease severity of a rice variety among inoculations by clipping off half, one-fourth, and one-eighth length of leaf. However, the inoculation by cutting half length of leaf could evaluate the disease resistance among the four rice varieties, except the japonica variety in the first crop trials. In addition, the inoculation method with cutting half length of leaf on the 1st and 2nd leaf from top could consistently distinguish the disease resistance of the rice varieties, except the japonica variety in the first crop trials.

Key words:Rice, Bacterial leaf blight of rice, Resistance screening techniques

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