MODULATION OF CERTAIN PHYSIOLOGICAL PARAMETERS TO SALINITY IN <em>CASUARINA</em> <em>EQUISETIFOLIA</em> SEEDLINGS INOCULATED WITH FIVE DIFFERENT <em>FRANKIA</em> STRAINS

Abstract

The salinity tolerance of Casuarina equisetifolia inoculated with five Frankia strains was evaluated by measuring the needle transpiration, diffusive resistance and seedling water potential of the plant. The seedlings were inoculated in the form of nodule suspension and subjected to four salt treatments, viz. control (T₀), 0.15 mg (low) (T₁), 1.5 mg (medium) (T₂) and 15 mg (high) (T₃) of NaCl per gram of soil. The low salt concentration increased the transpiration and reduced the stomatal resistance but maintained a higher water potential. On the other hand, the medium and high concentrations drastically reduced the transpiration by increasing the stomatal resistance resulting in a lowwater potential and thus ultimately the death of seedlings. Besides, the good growth of Casuarina seedlings was observed with two Frankia sources, namely Sugar-cane Research Station [Tamil Nadu Agricultural University (Cuddalore)] and Marakanam.