Germination and morphophysiological responses of flax (Linum usitatissimum L.) ecotypes to salinity stress

Salinity is one of the most important factors that limit plant growth in many regions of the world. In order to evaluate the effects of salinity stress on germination, growth and some physiological characteristics of flax, two separate experiments were carried out in the laboratory and greenhouse. The experimental factors included three ecotypes of flax (Kurdistan Native, L18, E37) and four salinity levels (0, 50, 100 and 150 mM NaCl). The results showed that with increasing salinity, germination percentage, germination rate, seedling vigor index, length and dry weight of hypocotyl and radicle decreased as compared to the control. At 150 mM salinity, Kurdistan Native and E37 ecotypes had the highest and lowest germination and seedling growth, respectively. Also, salinity decreased shoot and root length, shoot and root dry weight and relative water content, whereas, increased electrolytes leakage and soluble sugars. Kurdistan Native had the highest shoot and root dry weight, relative water content and total soluble sugar at 150 mM salinity followed by L18 and E37 ecotypes. At salinity of 150 mM, Kurdistan Native had the lowest electrolyte leakage and L18 and E37 ecotypes had the highest electrolyte leakage. In general, the most sensitive and most tolerant ecotypes were E37 and Kurdistan Native, respectively. Therefore, Kurdistan Native has potential for cultivation in areas with saline water.