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) -II. 내산성(耐酸性) R. meliloti 의 기내선발(器內選拔) 및 토양(土壤) 접종효과(接種效果)

Studies on the Development of Acid Tolerant and Superior Nitrogen Fixation Symbionts for Pasture on Hilly Land -II. Selection of Acid Tolerant R. meliloti in virto and Inoculation Effect in Soils

우수(優秀) 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, 기존(旣存) 알팔파 목야지(牧野地)에서 분리(分離)한 근류균(根瘤菌)으로부터 기내(器內) 내산성(耐酸性) 균주(菌株) 탐색(探索)과 토양(土壤)에서 선발균주(選拔菌株)의 내산성(耐酸性) 발현(發現)을 조사(調査)한 결과(結果)는 다음과 같았다. 1. pH 5.0의 시험관배지(試驗管培地)에서 근류형성(根瘤形成)을 보인 균주(菌株)는 "YA03"과 "YA09"였으며 공생효과면(共生效果面)에서 "YA03"이 우수(優秀)하였다. 2. "YA03"균주(菌株) 접종(接種)에 의(依)한 알팔파 생육(生育)과 질소(窒素) 고정력(固定力)은 무비(無肥)에서 뿐만 아니라 요소(尿素) 1.25mM 농도(濃度)에서 타균주(他菌株)보다 좋았다. 3. 알팔파 생육(生育)에 대(對)한 질소수준별(窒素水準別) "YA03" 균주(菌株)의 알팔파 접종효과(接種效果)는 접종(接種)+요소(尿素) 1.25mM > 접종(接種)+요소(尿素) > 무시용(無施用) > 무접종(無接種)+요소(尿素) 2.5mM 순(順)으로서 근류균(根瘤菌) 접종(接種)과 함께 요소(尿素)를 여용(旅用)하는 것이 효과적(效果的)이었다. 4. pH 5.0인 산성척박지(酸性瘠薄地)에서 알팔파에 대(對)한 R. meliloti "YA03" 균주(菌株) 접종(接種)은 무접종(無接種)보다 320%, pH 7.5의 비옥(肥沃)한 토양(土壤)에서 무접종(無接種) 재배(栽培)보다는 31% 건물중(乾物重) 증가(增加)를 보이므로써 내산성(耐酸性)이 큰 R. meliloti 균주(菌株)로 "YA03"를 선발(選拔)하였다.

A study was conducted to obtain acid tolerant and superior Rhizobium meliloti strain for alfalfa on hilly acid soils. With host plant, eight isolates of R, meliloti selected in the vicinity of Milyang were evaluated for their ability to establish symbiotic effectiveness in acidified tube culture medium and vermiculite pot with different urea levels. Among isolates "YA03" was characterized for the ability to manifest to acid tolerance in three different soils of which pH were 5.0, 6.0, and 7.5. The results obtained were summarized as follows: 1. Of eight isolates "YA03" and "YA09" performed nodule in the tube medium of pH5.0, and in the symbiotic effectiveness YA03 was superior to others. 2. Alfalfa growth and $N_2-fixing$ activity by the inoculation of "YA03" isolate were better than others at the level of urea 1.25mM as well as nonurea. 3. Application of urea with inoculation of "YA03" islate to alfalfa was one of the effective factors for symbiotic effectiveness. 4. In infertile soil of pH5.0 inoculation of R. meliloti "YA03" to alfalfa caused the increase of shoot dry matter of 320% as compared to the control, and the total amount of yield was 131% as much yield in moderate fertile soil of pH7.5. Finally R. meliloti "YA03" isolate was selected as an acid tolerant strain.