[Effects of NaCl stress on cation contents in seedlings of two pumpkin varieties].

Effects of different concentration NaCl stress on cation contents of pumpkin cultivars (Cucurbita ficifolia and Cucurbita moschata) usually used as rootstocks of cucumber were studied. The results showed that, in both cultivars treated with 150, 300 and 500 mmol/L NaCl for 7 d, increasing salinity caused in increasing retardation of shoot and root growth, and reduction of shoot relative water content (Table 1). With increasing NaCl concentration, Na(+) content increased while K(+) content decreased distinctly in roots, stems and leaves of both cultivars. And Na(+) and K(+) contents in different organs were in the orders roots>stems>leaves and stems>leaves>roots respectively (Fig.3). There were less Na(+) in root, stem and leaf (Fig.3), more free proline and soluble sugar in leaves (Fig.1, 2), and higher shoot relative water content (Table 1) in C. ficifolia than in C. moschata. So there are differences between C. ficifolia and C. moschata in osmotic adjustment mechanisms and selective absorption and transportation of different cations, and the salt tolerance of C. ficifolia is higher than C. moschata.