토양중(土壤中)에서 생육억제(生育抑制)에 필요한 유효농도(有效濃度)를 식물별(植物別)(화본과 I.R, 십자화과무)로 알아보기 위하여 무균한천배지(無菌寒天培地)에 제초제(除草劑) 4종(種)을 농도수준별(濃度水準別)로 처리(處理)하여 생육억제(生育抑制)를 조사(調査)한 결과(結果)는 다음과 같다. 1. 공통(共通)된 석향(傾向)으로 4종(種)모두 초장(草長)보다는 근장억제(根長抑制)가 보다 컸으며 무 보다 I.R에 대한 억제(抑制)가 월등(越等)하게 컸다. 2. I.R의 근장(根長)과 초장(草長)을 50% 이상억제(以上抑制)시키는 농도(濃度)는 nitralin 0.036ppm과 0.132ppm이고 napropamide는 0.027ppm과 0.071ppm이었다. 또 pendimethalin은 0.063ppm과 0.097ppm이고 ethalfluralin은 0.042ppm과 0.092ppm이었다. 그러나 무의 근장(根長)과 초장(草長)을 50% 억제(抑制)시키는 농도(濃度)는 nitralin은 1.028ppm과 10ppm 이상, napropamide는 0.515ppm과 10ppm 이상이었다. pendimethalin은 1.925ppm과 4.885ppm, ethalfluralin은 2.669ppm과 10ppm 이상이었다.
This experiment was conducted to identify the relationships of concentration with phytotoxic rate of dinitroamide and acid amide herbicides which have showed the longest residual period in soil. Four herbicides treated showed greater inhibition on roots than shoots, greater inhibition by herbicides was obtained for Italian ryegrass than for Radish. Nitralin, pendimethalin, and ethalfluralin at 0.01ppm gave about 20% inhibition of Italian ryegrass roots, whereas about 47% inhibition was obtained with napropamide. Fifty percent inhibition($I_{50}$) of roots and shoots of Italian ryegrass was 0.036 and 0.132ppm for nitralin. 0.063 and 0.097ppm for pendimethalin. 0.042 and 0.092ppm for ethalfluralin. 0.027 and 0.071ppm for napropamide respectively. On the other hand, $I_{50}$ of roots and shoots of Radish was 1.028 and over 10ppm for nitralin. 1.925 and 4.885ppm for pendimethalin, 2.669 and over 10ppm for ethalfluralin, and 0.515 and over 10ppm for napropamide respectively. There was positive correlation between the concentration of herbicides and growth inhibition of Italian ryegrass and radish.
