Factors and Recovery of Herbicide Phytotoxicity on Direct - seeded Rice - I. Variation Factors of Phytotoxicity

직파(直播)벼의 제초제(除草劑) 약해(藥害) 요인(要因)과 회복(回復)에 관한 연구(硏究) - I. 약해(藥害)의 변동(變動) 요인(要因)

This experiment was conducted to investigate the factor of phytotoxicity for herbicides(bensulfuron methyl, pyrazosulfuron-ethyl, dimepiperate, molinate) on flood direct-seeded rice. The phytotoxicity of herbicides was evaluated under controlled environment condition. Bensulfuron methyl and pyrazosulfuron-ethyl reduced more rice growth, especially root growth on low temperature(20/$11^{\circ}C$) than high temperature(30/$22^{\circ}C$) cultivations. The phytotoxicity of bensulfuron methyl and pyrazosulfuron-ethyl were increased relatively by non-nutrient and nutrient solution. cultivation, respectively. The rice applied bensulfuron methyl and pyrazosulfuron-ethyl with pH 3.5, 5.5, 7.5 and 9.5 solution became low growth rate on low pH of pH 3.5 and 5.5 solution cultivation. Bensulfuron methyl application with pH 5.5 and pH 7.5 solution, and pyrazosulfuronethyl application with pH 7.5 and 9.5 solution reduced rice growth inhibition. The root growth of rice seeded in 6cm depth of water solution applied herbicides was suppressed by bensulftuon methyl and pyrazosulfuron-ethyl, the growth of shoot was suppressed heavily by dimepiperate and molinate, in particular dimepiperate suppressed about the growth of 90%. The phytotoxicity of pyrazosulfuron-ethyl became high on light clay soil of non-fertilizer condition and sand loam soil of fertilizer condition, bensulfuron methyl became high on sand loam soil.

벼 담수직파시 제초제에 의한 약해의 원인을 구명하고자 온도, 용액의 pH, 수심, 토성 및 영양(營養)의 유무(有無) 등의 조건하에서 실험을 실시한 결과는 다음과 같다. 1. Bensulfuron methyl 및 pyrazosulfuron-ethyl 처리는 20/$11^{\circ}C$에서 30/22$^{\circ}C$에서보다 벼 생육 억제 정도가 컸으며, 특히 근부(根部)에서 현저히 컸다. Dimepiperate 및 molinate 처리는 저온 (20/$11^{\circ}C$) 고온(30/$22^{\circ}C$) 에서 생육억제 정도가 컸으며 경엽부(莖葉部)에서 현저하였다. 2. 무영양(無營養) 조건에서는 bensulfuron methyl 처리에서, 영양(營養)조건 에서는 pyrazosulfuron-ethyl의 처리에서 생육 억제 정도가 컸다. 3. pH3.5, 5.5, 7.5 및 9.5 용액에 bensulfuron methyl 및 pyrazosulfuron-ethyl 처리시 벼 생육은 pH3.5 및 5.5의 낮은 pH에서 저조하였으며, 무처리 대비한 생육 억제정도는 bensulfuron methyl 처리는 pH5.5 및 7.5에서 pyrazosulfuron-ethyl 처리는 pH7.5 및 pH9.5에서 낮았다. 4. 수심 6cm의 심수조건에 bensulfuron methyl 및 pyrazosulfuron-ethyl 처리시는 근부(根部)의 생육이, dimepiperate 및 molinate의 처리는 경엽부(莖葉部)의 생육이 크게 억제되었으며, 특히 dimepiperate처리는 90% 정도 억제되었다. 또한 pyrazosulfuron-ethyl+molinate의 처리에서 bensulfuron methyl+dimepiperate 처리보다 경엽부(莖葉部)의 억제정도가 컸다. 5. Pyrazosulfuron-ethyl 처리는 무비구는 식양토에서, 시비구는 사양토에서 생육저해 정도가 컸으며, bensulfuron methyl 처리는 사양토에서 생육이 저조한 경향이었다.