Journal of Taiwan Agricultural Research

Author:Su-Chen Lin*, Chun-Yu Zheng, Chao-Yi Wang, Chi-Yu Chen, and Wei-Lun Lin

Abstract:

    In recent years, bakanae disease of rice caused by Fusarium fujikuroi Nirenberg seems getting worse and widespread in Taiwan. In order to explore the influence of soil physical and chemical properties on the disease occurrence, 3 inoculation methods in 8 soil samples were conducted in greenhouse at Taiwan Agricultural Research Institute. The 8 soil samples were collected respectively from (1) Fenyuan, Changhua county, (2) Wanluan, Pingtung county, (3) Hemei, Changhua county, (4) Siansi, Changhua county, (5) Chutang, Changhua county, (6) Erlin, Changhua county, (7) Fangyuan, Changhua county, and (8) Chiali, Tainan county. The tested rice cultivar was ‘Kaohsiung 139’. There were three pathogen inoculation treatments: (1) seed inoculation, rice seeds were submerged in spore suspension before soaked in water for producing radicals; (2) radical inoculation, the germinating seeds with radicals were submerged in spore suspension before planting; (3) soil inoculation, soils were directly mixed with spore suspension . The inoculation densities respectively were 4.5 × 10⁶ spores mL^-1, 4.5 × 10⁶ spores mL^-1, and 5.4 × 10⁵ spores g^-1 soil. Thirty five days after planting, plant growth and mortality of rice were surveyed. The results indicated that rice seed inoculation treatment, if compared with the other two treatments, showed the highest mortality rate and the lowest plant dry weight. Among the 8 testing soil samples, the highest mortality rate was found in Fenyuan 66%, followed by Hemei 45%, Wanluan 29%, and Siansi 23%. In addition, the mortality rates of seed inoculation in 8 soil samples showed a significantly negative linear correlation (P < 0.05) between soil pH, available calcium and boron, respectively. As to the other soil physical and chemical properties, they did not show any significant linear correlation (P > 0.05). The highest mortality rates in both radical inoculation and soil inoculation treatments were 20% and 12%, respectively, in Fenyuan soil; however, the mortality rates in the other 7 testing soil samples showed no significant difference if compared with control. In this experiment, the results suggested that high occurrence potential of bakanae disease may be precautious especially if the rice seeds were infested with Fusarium fujikuroi in the previous 4 soil sampling sites (Fenyuan, Hemei, Wanluan, and Siansi) or any location with similar soil physical and chemical properties.

Key words:Bakanae disease of rice, Fusarium fujikuroi, Soil properties

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