Effects of Iso-Osmotic Na+, Cl- and NaCl Stress on the Plant Growth and Physiological Parameters of Grafted Cucumber

The present study was conducted to investigate the effects of iso-osmotic Na+, Cl-and NaCl stress on the plant growth and physiological parameters of self grafted and Figleaf gourd grafted cucumber. The results showed that, compared to non salt stress cucumber, Na+, Cl- and NaCl stress significantly decreased the plant growth. By comparison, less effect was induced by Cl-, and more effect was induced by Na+ and NaCl. Compared to self-grafted cucumber, Figleaf gourd grafting significantly increased the tolerance of cucumber to Na+ and NaCl stress. The shoot water content, Na+ content of root, K+, Ca2+ contents of stem and leaf, as well as leaf SOD activities were much higher in the Figleaf gourd grafted plants, while Na+ contents of stem and leaf were much lower than self-grafted cucumber under iso-osmotic Na+ and NaCl stress. The above results suggested that the sensitivity of cucumber to Na+ and Cl-is different. The toxicity induced by Na+ is much higher than Cl-. The improved salt tolerance of cucumber by grafting onto Figleaf gourd was achieved mainly by higher accumulation of Na+ in the root, and limited Na+ transport to the shoot. Thus, Na+ exclusion in the shoot plays a pivotal role in the salt tolerance of grafted cucumber.