Although both sodium and chloride in high concentrations have toxic effects to plant growth, some plant species are more tolerant to Na⁺ stress than Cl⁻ and vice versa. Until now, few studies compare the effects of separate and combined toxicities of Na⁺ and Cl⁻ on nodulated leguminous plants. In this study, Na⁺-dominant, Cl⁻-dominant, and NaCl treatments were applied to two alfalfa cultivars with or without rhizobial inoculation. The results showed that high Na⁺ was more toxic than high Cl⁻ to alfalfa growth. Shoot dry weight reduction was found in Na⁺ but not Cl⁻-dominant treatments, and the reduction in root dry weight was caused by the additive effect of Na⁺ and Cl⁻ toxicities in uninoculated plants. Rhizobial inoculation significantly promoted plant growth by the improvement in both nitrogen nutrition status and root growth. At NaCl treatment, the promoted growth was also associated with the lower Cl⁻ concentrations in the inoculated plants relative to the uninoculated plants. Additionally, rhizobial inoculation induced the differential expression of the salt-response genes, MsHSP81.2 and MsCLC1. In conclusion, the above results indicate that both Na⁺ and NaCl toxicities reduced alfalfa growth, and the reductions were greater under NaCl toxicity conditions and were mainly caused by the additive effects of Na⁺ and Cl⁻ toxicities. Rhizobial symbiosis can alleviate separate and combined toxicities of Na⁺ and Cl⁻ through enhanced nitrogen nutrition and root growth, the change of the accumulation and partitioning of K⁺ and Cl⁻, and accordingly the differential expression of some salt-response genes. The above results offer an economical measure in the future application of biofertilizers for alfalfa salt tolerance.

虽然这两个钠离子和氯在高浓度的具有植物生长的毒性作用，一些植物物种更耐受的Na ⁺应力比氯^- ，反之亦然。到现在为止，一些研究比较娜单独及联合毒性的影响⁺和Cl ^-对根瘤化的豆科植物。在这项研究中，钠⁺ -dominant，氯^- -dominant，和NaCl处理被应用到两个苜蓿品种有或没有根瘤菌接种。结果表明，高娜⁺是不是高氯的毒性更大^-苜蓿生长。地上部分干重减少在娜发现⁺而不是氯^--dominant治疗，并在根干重的减少是由钠的添加效果引起的⁺和Cl ^-中的未接种的植物毒性。根瘤菌接种通过改善氮素营养状况和根系生长来显着促进植物生长。在NaCl处理，推广生长也与下部相关联的氯^-浓度在接种的植物相对于未接种的植物。此外，根瘤菌接种诱导了盐反应基因MsHSP81.2和MsCLC1的差异表达。总之，以上结果表明，Na ⁺和NaCl毒性降低苜蓿的生长，并且减少是毒性的NaCl的条件下更大的并主要由Na组成的累加效应⁺和Cl ^-的毒性。根瘤菌共生可缓解的Na单独及联合毒性⁺和Cl ^-通过增强的氮营养和根的生长，积累的变化和K的划分⁺和Cl ^- ，并且相应的一些盐反应基因的差异表达。以上结果为将来在苜蓿耐盐性生物肥料中的应用提供了一种经济的措施。