Effect of NaCl Stress on Na~+ and Ca~(2+) Content in Different Cultivars of Pumpkin Seedlings

Variations of Na+,Ca2+content,the ratios of Na+/Ca2+ in shoot and root of 19 pumpkin cultivar seedlings were investigated after an 8 day exposure to 300 mmol/L NaCl.The results showed that the content of Na+significantly increased and that the ion balance was broken.The relative absorption of salt ions and nutritional elements were reflected in the variations of Na+content and the ratios of Na+/Ca2+ in shoot.Na+content in root and the ratios of Na+/Ca2+ in shoot in Q1(Qingli) were significantly higher than those in H2(Heimi pumpkin),H3(C.ficifolia).From these results,it can be inferred that the variation tendency of Na+content,the ratios of Na+/Ca2+ in shoot of different pumpkin cultivar seedlings were nearly in consistent with the salt injury index of those under NaCl stress.This further proved that strong salt-tolerance of Q1 was related to the low ratios of Na+/Ca2+ in shoot and the high content of Ca2+ ions under salt stress.The sensitivity of H2 and H3 to salt was connected with the high ratios of Na+/Ca2+ in shoot and the low content of Ca2+ ions under salt stress.