Response Of Salix Hybrid To Salt Stress And The Regulation Of Exogenous Nitric Oxide

The salix hybrid seedlings were treated with NaCl, Na₂SO₄, NaHCO₃, Na₂CO₃ , sodium nitroprusside(SNP) and the exogenous donor of nitric oxide (NO), and the morphological indexes, cell membrane system, osmoregulation system and root activity were systematically studied to discuss the response of seedlings to salt stress, the salt resistance mechanism and to find methods for improving the salt resistance. The rooting of seedling in water culture was also studied to supply theoretical guidance for seedling production. The results were as follows:1. There was difference between theoretical and actual salt content and pH values after cycling salt stress. The pH value increased with alkali ratio in the complex alkali-saline treatments, and the pH value changed more obviously between the groups than within group, with pH value ranging from 6.89 to 10.16.2. Under the stress of neutral salt (NaCl and Na₂SO₄) stress, alkaline salt (Na₂CO₃ and NaHCO₃) stress and complex alkali-saline stress, the salt stress symptoms appeared after 40 days and seedlings began to die after 70 days. The seedling height, caliper and leaf area decreased with prolonged stress time and increasing salt concentrations. Meantime, cell membrane was damaged and osmoregulation ability ascended at first then declined and root activity decreased, but different salt was different in stress degrees. Comprehensive analysis of all kinds of salts showed that the salt-tolerances of NaCl, Na₂CO₃, complex alkali-saline A, complex alkali-saline C, complex alkali-saline D and complex alkali-saline E were about 50 mmol·L-1, but those of Na₂SO₄, NaHCO₃ and complex alkali-saline B were about 75 mmol·L-1. The stress damages of different salt types, from least to most, could be taxised as: NaHCO₃2SO₄2CO₃2SO4 and NaHCO3 could be 25mmol·L-1, and the rooting could not be found under Na₂CO3 stress.