Salt tolerance in Salvadora persica: Osmotic constituents and growth during immature phase

Soil salinity is an important constraint in agricultural crop production. Salt affected soils which are quite prevalent in Dhal region of Gujarat State are lying either barren or possess some native hardy species and coarse grasses. Salvadora persica, a potential source of non-edible seed oil rich in C₁₂ and C₁₄ fatty acids, has been found growing luxuriantly on highly saline soils having salinity up to 80 dS m⁻¹ in the top 30 cm layer. Though ionic composition and salt compartmentation of plants growing on highly saline black soils have been reported, studies on biochemical basis of salt tolerance have received inadequate attention. The present study is on identifying the plant metabolites which act as osmotic agents in turgor maintenance and growth. Results indicate that keto acids like α-ketoglutaric acid, pyruvic acid and oxaloacetic acid were found to increase with salinity, which play an important role in synthesising the amino acids like glutamic acid, alanine, glutamine, aspartic acid and asparagine. Proline was also found to increase several folds under salinity. These amino acids along with other inorganic ions play an important role in osmotic adjustment in S. persica, thereby enabling this species to exhibit good growth and canopy spread even under high salinity.