土壤中大豆根瘤菌优势类群以及与寄主共生关系的多样性

我国大豆种植区使用人工选育制成的根瘤菌剂接种效果不稳定。研究指出南方、北方和黄淮流域的6个省土壤中分布的主要Bradrhizobium.japonicum是DH444、USDA110、LL120、005和C224血清型的菌株,主要的Rhizobium.fredii是2048、USDA217、DE1611、2120和2077血清型的菌株。它们占每个取样地点分离物总数的60.3-81.6％。植物感染结瘤法测得大豆种植地点土著根瘤菌菌数在104/克土以上。盆栽试验表明大豆根瘤菌与大豆品种共生时有较强的亲和选择性和共生效应的多样性,其有效结瘤和固氮效率与根瘤菌个体菌株和大豆品种极相关。大多数土著大豆根瘤菌是低或中效固氮的菌株,因而认为选育抗土著根瘤菌而有利于人工接种菌株结瘤的大豆品种和强竞争性的高效菌株仍是提高我国大豆生产的有效途径。

THE DIVERSITY OF DOMINANT SOYBEAN RHIZOBIUM TYPE IN CHINESE SOILS AND ITS SYMBIOTIC CHARACTERISTIC WTIH HOST

The applying of soybean rhizobium inoculation were usually not success in Chinese soybean field. Our results indicated that serogroup 2048, USDA217. DE1611, 2120. 2077 and DH444, USDA110, LL120, 005, C224 were dominant rhizobium population in the South, North and Yellow River Valley of China. These dominant indigenous isolates accounted for 60.3-81.6% of total isolates of per site tested. Each of soil tested in soybean production region contained > 10⁴ cell of soybean rhizobium per gram. Several pot-culture experiments showed the diversity of nodulating. N₂-fixing effectiveness of strain with soybean cultivar. Most of indigenous strains were relatively low or medium-efficiency fixer in contrast with B.Japonicum 113-2. Therefore, it will be our subsequent object to select and breed soybean genotype that can resist nodulation of indigenous strains and rhizobium that can compete nodulation against indigenous strains.