Research On Mechanism Of Salt-tolerance And Selection Of Salt-tolerant Varieties Of Differently Genetic Pumpkins

Pumpkin is an annual herb. C. moschata Duch., C. pepo L, C. mamxima Duch, C. ficifolia Bouch and C. mixta Pang are included. Soil salinity deteriorates severly the growth, yield and quality of pumpkin. Therefore, how to enhance the salinity tolerance of pumpkin becomes a very important thing that people pay close attention to. In the experiment, there are 19 supplied materials. We studied the salt-tolerant mechanism of different pumpkin varieties in phase of seeds' germination and seedlings, and the effects of GB on Qing li and C. ficifolia Bouch in order to offer some references for the culture and selection of salt-tolerant cultivation.1. Nineteen different pumpkin varieties were treated with 300mmol/L NaCl and the salt tolerance at the stage of seed germination studied. The results showed that the salt stress affected germination rate, germination potential, germination index and activity index, and led to the increase of electrolytic leakage and decrease of root fresh weight and root activity. It was indicated that Q1, R2 and N1 were the most salt tolerant to salt stress.2. It was salt injury index, electrolytic leakage, MDA, root activity, Pro and soluble sugar content that were investigated. The results showed that Ql was the most salt-tolerance;J1, J2, R1, R2, T1, T2, B1, W1, W2, L1, L2, Z1, Z2, S1 and H1 were intermediate;H2 and H3 were the most sensitive to salt stress.3. The effects of salt stress on salt injury index, electrolytic leakage, MDA, Pro, Chl., soluble sugar content and root activity in pumpkin seedling of 19 varieties were investigated. The results indicated that salt stress at the pumpkin seedling stage led to the increase of electrolytic leakage, MDA, Pro and soluble sugar content, the decrease of root activity and the content of Chl. was uncertain. It was proposed that salt injury index, electrolytic leakage and MDA content could be suitable for selecting salt-tolerant pumpkin variety except root activity, soluble sugar, Pro and Chl. content. 4. The effects of 300mmol/L NaCl stress on ion content were studied. The results showed that due to the salt stress, the content of Na⁺ obviously increased while K⁺ content decreased. Consequently, ion balance was broken. The content of Na⁺, Na⁺/K⁺, Na⁺/Ca²⁺, Na⁺/Ca²⁺, SNa⁺,K⁺ and SNa⁺,Ca²⁺ at seedling stage basically reflected the salt-tolerance of plant and might be suitable to select salt-tolerant pumpkin variety.5. C.ficifolia and Qingli under the 300mmol/L NaCl stress were treated with different concentration of GB and electrolytic leakage, MDA, soluble sugar, Chi. content and root activity in phase of pumpkin seedling studied. The results showed that GB could decrease Cell membrance permeability and salt stress—induced injuries of cell;GB also could delay the accumulation of MDA (Product of membrance lipid peroxide). The suitable concentration of GB could obviously increase soluble sugar content and enhance the activity of osmotic adjustment and mitigate the seedling injury caused by salt ion and loss of pumpkin seedling water.In conclusion, the experiment established salt-tolerance and selection of different genetic pumpkin and set up system of comprehensive evaluation. Salt-tolerant mechenism of them was perfected. But some indicators such as soluble sugar and Pro need further studying.