Plant Growth-Regulating Activities of 3-Hydroxy-5-methyl Isoxazole : III. Effect of 3-hydroxy-5-methyl isoxazole on the reduction of overhead flooding damage and herbicide injury to rice seedings

摘要

The present study was undertaken to investigate the effect of 3-hydroxy-5-methyl isoxazole (HMI) on the reduction of overhead flooding damage and herbicide injury to rice seedlings. HMI was applied to the soil immediately after sowing of rice seeds in the seedling beds. Seedlings transplanted from these beds showed greater rooting ability and increased physiological activity in their roots. It was observed that the pre-treatment of rice seedlings with HMI promoted the shoot elongation, compared with untreated seedlings, under overhead flooding condition. A drastic reduction in overhead flooding damage was observed when rice seedlings were pre-treated with HMI. The pre-treament of rice seedlings with HMI also reduced the Phytotoxic action of five of seven herbicides applied three days after transplanting. The five herbicides whose phytotoxic action was reduced were simetryne, MCC·MCP, NIP (nitrofen), CNP and DCPA (propanil). The reduced submergence damage and herbicidal injury observed in rice seedlings may be due to increased seedling vigor induced by HMI. The improved physiological condition in these rice seedlings may increase their resistance to submergence treatment and some injurious herbicides.