Studies On Salt-tolerance Of Two Pumpkin Cultivars As Rootstock And Cumumber Seedlings Grafted On Them

Cucumber is sensitive to salt. Soil salinity deteriorates severely the growth and yield of cucumber. Grafting culture can effectively enhance the ability of cucumber to resist adversity and has been applied widely. It is significant to compare salt tolerance of different rootstocks and study the mechanism of salt tolerance of grafting cucumber. Salt tolerance and characteristics of two pumpkin cultivars (Cucurbita ficifolia Bouche. and Cucurbita moschata Duch.ex Poir.), usually used as rootstocks of cucumber, and cucumber (Jinyou No.3) seedlings grafted on them under NaCl stress were studied mainly in osmotic adjustment and ion balance in order to investigate salinity tolerance of different rootstocks and offer some reference for the grafting culture of cucumber in practice.1. Two pumpkin varieties (Cucurbita ficifolia. and Cucurbita moschata.) were treated with different concentrations of NaCl (120, 180, 240 mmol/L ), and compared the salt tolerance in phrase of seed germination. The results indicated that Cucurbita moschata. has stronger salt-tolerance than Cucurbita ficifolia. in phrase of seed germination under NaCl stress, with higher germination potential, germination rate, germination index, activity index and root activity, and lower salt injury index and leakage of radicle in Cucurbita moschata. than those in Cucurbita ficifolia.2. Salt tolerance of pumpkin cultivars (Cucurbita ficifolia and Cucubita moschata ) under different concentration NaCl stress was studied. The results showed that, in both cultivars treated with 150, 300 and 500mmoI/L NaCl for 7 days, Na salinity resulted in the deterioration of growth of shoot and root, the decrease of shoot relative water content, and the increase of MDA content and cell membrane permeability. With increase of 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 orders: roots>stems>leaves and stems>leaves>roots. There were less Na+ in root, stem and leaf, more free proline and soluble sugar in leaves, and higher shoot relative water content in Cucurbita ficifolia. than in Cucubita moschata. So there are differences between Cucurbita ficifolia. and Cucubita moschata. in osmotic adjustment mechanisms and the capacity of ionic selective absorption and transportation. According to synthesis comparison of results...