Journal of Taiwan Agricultural Research

Author:Lung-Che Chen, Yi-Shin Chen and Yung-Hsiung Cheng*

Abstract:

    A total of 2,606 rice varieties and strains from Taiwan were tested for their response to the blast disease at Chiayi blast nursery from 1990 to 2002. The incidence of blast disease varied with years and seasons. In general, the tested rice varieties and strains showed more resistant to the leaf blast than to the panicle blast. The average of entries resistant to the leaf blast was 19.5% higher than that resistant to the panicle blast. Among Japonica entries, the rice resistant to the panicle blast was highly positive correlated with that resistant to the leaf blast (r=0.65～0.91，P<0.01). The average of Indica rice resistant to the leaf and panicle blasts were 12.6 and 31.6% higher than that of Japonicas, indicating Japonica rice in general were more susceptible to blast disease than that of Indicas, particularly to the panicle blast. In addition, the difference in the scale of the blast incidence for Indicas and Japonicas between the first and second cropping season were 1.26 and 0.06, respectively, indicating the entries of Japonica rice appeared more susceptible to blast in the first cropping season than that of the second, while the Indicas showed a relatively unanimous in the two cropping seasons. The averaged incident scale of the tested rice in the upland nursery was 1.62 higher than that tested in the paddy nursery. Analyzing the relationship of the incident scales between the two different nurseries, the Japonicas in the paddy nursery were closely correlated to that recorded in the upland nursery (r=0.46～0.90，P<0.01). The response of newly developed blast-resistant varieties such as Taikeng 8, Taikeng 11, Taikeng 14 and Taikeng 16 etc. to the rice blast, were unstable and were easily to be overcame by the virulent races of the blast pathogen within 1 to 5 years after they were released for commercial cultivation in a wide area.

Key words:Rice, Blast, Blast nursery

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