A COMPARISON OF EXOGENOUS PROLINE APPLICATION METHODS IN ENHANCING SALINITY TOLERANCE OF FLEX (LINUM USITATISSIMUM L.)

Proline (Pro) is one of the compatible solutes that play an important role against salinity through osmotic adjustment and protecting membranes in plants. The aim of the present study was to determine the alleviation of salinity stress by the application of proline in flax plant. Three flax genotypes Roshni, Chandni and Desi were tested against salinity, i.e. 0 mM NaCl (Control) and 180 mM NaCl. Two levels of proline 0mM and5 mM and were applied through three different mods, i.e. pre-sowing seed treatment, foliar spray and root growing medium. Salinity substantially decreased the growth and yield of flax plants by decreasing shoot fresh, photosynthetic pigments (Chlorophyll a and b) with a concurrent decrease in both shoot and root Ca(2+ )and K+. A considerable increase in both shoot and root Na+, increased level of antioxidants (catalase, peroxidase, superoxide dismutase) and total soluble proteins was also observed in flex plants exposed to salinity stress. Exogenous application of proline enhanced the growth and yield of flex plants. This was accompanied by increased shoot fresh weights and antioxidants with a parallel increase in Ca2+ and K+ contents of shoot and root tissues. At the same time, a substantial decrease in both shoot and root Na+ was noted under exogenously applied proline. Among all proline levels, 5mM concentration showed the most improvement in growth and yield of salinity stressed flax plants. As observed from PCA model, foliar application of proline was the most effective in alleviating the adverse effects of salinity stress compared with rooting or water sprayed flex plants.