Anatomical and physiological characteristics relating to ionic relations in some salt tolerant grasses from the Salt Range,Pakistan

Populations of three salt tolerant forage grasses (Cynodon dactylon, Imperata cylindrica, and Sporobolus arabicus) were collected from the salt-affected soils of the Salt Range and normal non-saline soils of the Faisalabad region to assess their mechanism of adaptation to saline stress by determining ion relations and some specific anatomical modifications. The population of S. arabicus from the Salt Range showed increased growth (root and shoot length, and root and shoot dry weights) under saline conditions. Salt tolerance in this species was related to structural modifications such as increased area of root, stem, leaf blade, and leaf sheath for toxic ion accumulation, increased vesicular hair density in leaves and aerenchyma formation in leaf sheath for ion exclusion. Uptake of toxic ions was high in the Salt Range population of C. dactylon and salt tolerance was related to ion exclusion through specific leaf structural modifications such as vesicular hairs. Salt tolerance in the Salt Range population of I. cylindrica was mainly associated with restricted uptake of toxic Na⁺ and Cl⁻ at root level, and accumulation of toxic ions via increased succulence in leaf blades and leaf sheaths in addition to some excretion of toxic ions through leaf sheath aerenchyma.