Analysis of the key stress factors in winter rape under simulated salinityalkalinity mixed condition

Strain index of seed germination rate、seedling leaf cell membrane permeability、MDA content、proline content、soluble protein content and root activity of Longyou No. 6 seeds and seedlings were determined between A factors of 4 kinds of salt for NaCl, Na2SO4, Na2CO3 and NaHCO3, composed of salt mole ratio for A1 (1∶9∶9∶1), A2(1∶1∶1∶1), A3(9∶1∶1∶9) and A4(1∶1∶9∶9) and B factors of 5 kinds of salt concentration for B1 (10 mmolL-1), B2 (20 mmolL-1), B3 (30 mmolL-1), B4 (40 mmolL-1)and B5 (50 mmolL-1) of the double factors. Twenty kinds of salinity and different pH of saline conditions were simulated to treat winter rape No.6 seeds and seedling 7D. The results showed that 20 kinds of salinity were from 10 to 50 mmolL-1 and pH was between 8.50 and 10.24. Seed germination rate, seedling root activity and soluble protein content were decreased and leaf cell membrane permeability, MDA content and proline content were increased with the increasing of the concentration of salt treatment. The degree of increase and reduction became higher among A1 to A4 in turn. The different salt composition in treatment reached significant difference (P0.05). All stress effect factors under saline mixed conditions were caused by salinity (Na+), pH, CO32- and Cl-. Stress factors of salinealkali and strain index of Longyou No. 6 seeds and seedlings had high linear correlation. The dominant factors of winter rape stress were pH、salinity (Na+)、CO32- and stress effect on winter rape Longyou No. 6 of Cl- could not be ignored.