Influence of Organic Ligands on Phytotoxicity of Paraquat

유기(有機)리간드가 Paraquat의 약해(藥害)에 미치는 영향

Organic ligands in the environments are expected to play an important role in regulating the biotoxicity and fate of pesticides. Influences of dissolved humic and fulvic acids on the phytotoxicity of Paraquat were investigated using a bioassay with hydroponically grown rye as indicator species. Levels of Paraquat in water culture media were ranged from 0 to $12_{{\mu}M}$ and those of humic or fulvic acid were 1.0mM as a soluble carbon. Media were prepared in a factorial combination with pHs of 4.5, 6.5 and 8.5, Standard curves of necrosis days, fresh weight, and growth rates, as Phytotoxicity Indices, versus Paraquat concentrations were employed to evaluate the effects of organic ligands on phytotoxicity of paraquat. Organic ligand itself had little effect on rye growth, but Paraquat showed a high degree of toxicity. Paraquat started to show an intensive injury to rye at $0.4{\sim}0.6{{\mu}M}$ and upper critical phytotoxic concentration was estimated to be 11.0${{\mu}M}$ In the presence of organic ligands, times required to cause necrosis due to Paraquat were delayed upto 40%. Fresh weights and growth rates were upto 20% higher in treatments of organic ligands plus Paraquat than that of Paraquat alone. Results demonstrated that complexation of organic ligand with Paraquat reduced the bioabailability of Paraquat to rye.

부식산과 흘브산이 Paraquat의 약해에 미치는 영향은 호밀의 생물검정을 통해 고사일수, 생중량 및 성장률에 관한 약해지표를 설정하고 Model을 도입하여 평가했다. 호밀의 생육상황에 대한 유기리간드 자체의 영향은 거의 없었으나, Paraquat의 독성은 매우 높았다. Paraquat의 약해가 강하게 나타나기 시작하는 농도는 $0.4{\sim}0.6{\mu}M$ 이었으며, 약해한계농도 (Phytotoxic Critical concentration)는 약 11${\mu}M$ 로 추정되었다. 유기리간드의 처리는 Paraquat의 약해에 의해 초래되는 고사일수를 약 40%까지 지연 시켰으며, Paraquat 단독처리구보다 생중량 및 성장률을 유의성있게 향상시켜, Paraquat의 호밀에 대한 약해를 줄여 주었다.