Enhancing NO3- supply confers NaCl tolerance by adjusting Cl- uptake and transport in G. max & G. soja

Abstract

The objective of this work was to elucidate NO3- supply, Cl- toxicity, and Cl-/NO3- interaction in Glycine max and Glycine soja under salt stress. G. max cultivars (Lee68 and Jackson) and G. soja accessions (BB52 and N23227) with different salt tolerance were chosen as the experimental materials. Effects of low (0.75 mmol/L), normal (7.5 mmol/L), and high (15 mmol/L) NO3- supply on growth, relative electrolytic leakage, and contents of Cl-, NO3-, Na+, K+ in roots and leaves of NaCl (50 and 100 mmol/L)-stressed plants were investigated. Results showed that, low NO3- supply led to serious salt damage on G. max and G. soja plants. While enhanced NO3-supply could significantly reduce relative electrolytic leakage and contents of Na+ and Cl- in roots and leaves accompanying with obvious NO3- increase and K+ maintenance. Thus, finally an improved growth and alleviated salt injury by reducing Cl-/NO3- and Na+/K+ ratios, especially for the relatively salt-sensitive Jackson and N23227 were obtained. Moreover, Cl-/NO3- and Na+/K+ ratios were significant or extreme significant positively correlated with relative electrolytic leakage, and significant or extreme significant negatively correlated with root vigor or plant fresh weight. It suggests that Cl-/NO3- ratio can be used as vital reference indexes as Na+/K+ for evaluating soybean salt tolerance.