Effects of Salt Stress on Seed Germination and Seedling Growth of 6 Forage Sorghum dochna Varieties

Six forage Sorghum dochna varieties were used as materials for seed germination tests under 5 gradient ratios of NaCl and Na₂SO₄ solution（0（ck）, 50, 100, 150, 200 mmol/L）. Germination rate, germination potential, bud length, root length, salt damage rate, plant height, stem diameter, dry/fresh ratio and soluble sugar content were determined. To explore the effects of different salt stress on seed germination characteristics and seedling growth. The results showed that with the increase of NaCl and Na₂SO₄ concentrations, the germination rate, germination potential, bud length, root length, plant height, stem diameter and dry-fresh ratio of forage sweet sorghum seeds gradually decreased, and the salt damage rate and soluble sugar content gradually increased. When NaCl concentration was greater than 100 mmol/L and Na₂SO₄ was greater than 50 mmol/L, the germination rate, germination potential, plant height, stem diameter and dry-fresh ratio of seeds significantly decreased（p＜0.05）. When the concentration of NaCl was 200 mmol/L, Dakar, Manatee and Zhongketian2 stopped growing, while when the concentration of Na₂SO₄ was greater than 150 mmol/L, Dakar, Manatee, Zhongketian438 and Zhongketian2 stopped growing, indicating that the harmful effect of Na₂SO₄ stress was more prominent. According to the comprehensive evaluation by membership function method, the salt tolerance of the six varieties at germination and seedling stage was as follows: Dakar＞3701＞Zhongketian438＞Zhongketian2＞Manatee＞Dahlix and 3701＞Dahlix＞Dakar＞Manatee＞Zhongketian438＞Zhongketian2. In conclusion, the forage Sorghum dochna 3701 had strong salt tolerance and was suitable for planting in saline-alkali areas.