Studies on the Development of Acid Tolerant and Superior Nitrogen Fixation Symbionts for Pasture on Hilly Land -I. The Degrees of Acid Tolerance of Rhizobia from the Pastures in Yeongnam Area

야산(野山) 목초지용(牧草地用) 내산성(耐酸性) 우수(優秀) 질소고정균주(窒素固定菌株) 개발(開發) -I. 영남지방(嶺南地方) 목야지(牧野地) 근류균(根瘤菌)의 내산성정도(耐酸性程度)

This study was conducted to evaluate the degree of acid tolerance of indigenous Rhizobium in natural soils, and to select the superior Rhizobia for legume forage on hilly land. 153 Rhizobial strains isolated from two host genera, Medicago and Trifolium in the pastures of Yeongnam area were screened on acidic agar plates. The results obtained are summarized as follows: 1. The degrees of acid tolerance of R. meliloti and R. trifolii were ranged from 4.3 to pH 5.5 and from 4.0 to pH 5.5 respectively. 2. Among acid tolerant Rhizobia isolates, two strains of R. meliloti at pH 4.3 and three strains of R. trifolii at pH 4.0 were shown to have the activities of nodulation and nitrogenase. 3. R. trifolii strains were shown to survive about 80 to 99% at the pH range 4.8 to 5.0, while R. meliloti were about 35 to 47% at that pH range. Therefore, more acid tolerant R. meliloti should be developed for legume forage in Korean hilly land.

우량(優良) 질소고정균주(窒素固定菌株)를 개발(開發)하여 척박(瘠薄)한 야산(野山) 개발지(開發地)에서 효율적(效率的)인 초지조성(草地造成)을 꾀하고자, 영남지역(嶺南地域) 목초지(牧草地) 근류균(根瘤菌)의 내산성(耐酸性) 정도(程度)를 시험(試驗)한 결과(結果)는 다음과 같았다. 1. 분리균주(分離菌株)의 내성산도(耐性酸度)는 R. meliloti의 경우(境遇) pH 4.3~5.5, R. trifolii에서는 pH 4.0~5.5 범위(範圍)이였음. 2. 내산성(耐酸性)이 큰 R. meliloti M3 및 M4와 R. trifolii T27, T30, T31, T33 균주(菌株)는 숙주접종(宿主接種)으로 근류(根瘤)를 형성(形成)하였고 질소고정력(窒素固定力)도 있었다. 3. 우리나라 야산(野山)의 평균산도(平均酸度)인 pH 4.8~5.0에서의 내산성(耐酸性) 균주(菌株)는 R. trifolii는 80~99%였으나 R. meliloti는 35~47%에 지나지 않으므로 보다 내산성(耐酸性)이 큰 R. meliloti의 선발(選拔)이 요구(要求)됨.