ABSTRACT

Salinity is one of the major problems when it comes to soil fertility and agricultural productivity. In this regard, this study aimed to elucidate the influence of four salinity levels (0, 20, 50, 100 mM NaCl) on the soybean growth and the nodulation by rhizobia inoculated on the soybean variety CNS. Additionally, the compatibility of soybean varieties with the seven representative strains of rhizobia was also investigated. Through the compatibility test, it was revealed that the Sinorhizobium (Ensifer) fredii USDA 191 and the three bradyrhizobia (Bradyrhizobium japonicum USDA 6^T, B. elkanii USDA 31, and B. diazoefficiens USDA 110^T) showed compatible nodulation with the Rfg1 genotype soybean, whereas, the S. fredii USDA 192, 193, and 205^T showed incompatible nodulation. The inoculation tests with bradyrhizobia (USDA 31, 110^T) and sinorhizobia (USDA 191, 192, 193) indicated a better growth of soybean for bradyrhizobia than the sinorhizobia until 50 mM NaCl. Note that even though the symbiotic efficiency at each strain was not different among 0, 20, and 50 mM NaCl treatments, the symbiotic efficiency of bradyrhizobia was higher than the sinorhizobia at each NaCl treatment. The result of the mix inoculation test indicated that the nodule occupancy rate of strain USDA 191 increased significantly along with the NaCl concentration but strain USDA 110^T showed an opposite response. These results indicate a positive relationship between the soybean growth and the nitrogen fixation ability of the inoculant under salt-stress conditions. Furthermore, the results obtained from the mix inoculation test partly describe the dominance of sinorhizobia under saline conditions.

摘要

盐分是土壤肥力和农业生产力的主要问题之一。在这方面，本研究旨在阐明四种盐度水平（0、20、50、100 mM NaCl）对大豆生长的影响以及接种于大豆品种CNS的根瘤菌的结瘤作用。此外，还研究了大豆品种与7种代表性根瘤菌菌株的相容性。通过相容性试验，据透露，中华根瘤菌（Ensifer）费氏中华根瘤菌USDA 191和三个bradyrhizobia（大豆慢生根瘤菌USDA 6 ^Ť，B. elkanii USDA 31，和B. diazoefficiens USDA 110 ^Ť）显示出与Rfg1基因型大豆相容的根瘤，而弗雷德氏菌USDA 192、193和205 ^T显示出不相容的根瘤。缓生根瘤菌（USDA 31，110 ^T）和中华根瘤菌（USDA 191，192，193）的接种试验表明，直到50 mM NaCl，大豆根瘤菌的生长要比中华根瘤菌更好。请注意，即使在0、20和50 mM NaCl处理中每个菌株的共生效率没有差异，但在每个NaCl处理中，缓生根瘤菌的共生效率都高于鼻窦菌。混合接种试验的结果表明，USDA 191菌株的结节占有率随NaCl浓度的增加而显着增加，USDA 110 ^T菌株的结节占有率显着增加。表现出相反的反应。这些结果表明，在盐胁迫条件下，大豆的生长与孕育剂的固氮能力呈正相关。此外，从混合接种试验中获得的结果部分描述了在盐条件下鼻窦菌症的优势。