Saturday, 15 July 2006

The effect of Inorganic Elements on the Reduction of Phytophthora Stem Rot Disease of Soybean.

Takuma Sugimoto, Kazuhiko Watanabe, Minoru Matsuyama, Mikihiro Sugimoto, and Shinya Yoshida. Hyogo Agricultural Institute for Agriculture, Forestry and Fisheries, 1533 Minamino-oka, Befu, Kasai, Hyogo 679-0198, Japan, Kasai, Japan

The effect of several inorganic elements contained in B5 medium on Phytophthora stem rot disease reduction of Glycine max (L.) Merr. cv. Chusei-Hikarikuro was investigated using the agar medium inoculation method. Application of B5 solution prior to inoculation significantly inhibited infection compared with controls. The incidence of disease of cv. Chusei-Hikarikuro with and without B5 was 40.0% and 97.6%, respectively. Several levels of macro inorganic nutrients (A), micro inorganic nutrients (B), Fe-EDTA solution (C) and organic elements (D) in B5 were applied in an effort to evaluate disease suppression. The concentration of 100% and 250% of A element was effective in inhibiting infection, with an incidence of disease of 17.9% and 54.6%, respectively. On the other hand, 10% of A together with three other nutrients (B, C and D) was ineffective, where the incidence of disease was 74.3-97.6%. Four media (A+B+C, A+B+D, A+C+D, and B+C+D) were also tested. Although the incidence of disease increased when medium (B+C+D) was used, it decreased significantly when media containing A was applied. Various concentrations (0, 10, 100, 250, 500 and 1000%) of KNO3, (NH4)2SO4, MgSO4, CaCl2 and NaH2PO4 in the presence of A nutrients was investigated in an effort to determine the elements most effective in suppressing the incidence of disease. A concentration of 10–1000% CaCl2 greatly inhibited infection, where the incidence of disease was 5.6-42.1%. A concentration of 100% KNO3 led to marked suppression of disease. However, concentrations of 10-500% of (NH4)2SO4, Mg4SO4 and NaH2PO4 induced disease at the same level as that of controls.


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