Individual and additive effects of Na+and Cl−ions on rice under salinity stress

This study was attempted to assess the extent of toxicity contributed by Na+ and/or Cl− ions individually, besides their possible additive effects under NaCl using physiological and biochemical parameters. Despite the fact that most annual plants accumulate both Na+ and Cl− under saline conditions and each ion deserves equal considerations, most research has been focused on Na+ toxicity. Consequently, Cl− toxicity mechanisms including its accumulation/exclusion in plants are poorly understood. To address these issues, effects of equimolar (100 mM) concentrations of Na+, Cl− and NaCl (EC ≈ 10 dS m−1) were studied on 15-day-old seedlings of two rice cultivars, Panvel-3 (tolerant) and Sahyadri-3 (sensitive), using in vitro cultures. All three treatments induced substantial reductions in germination rate and plant growth with greater impacts under NaCl than Na+ and Cl− separately. Apparently, salt tolerance of Panvel-3 was due to its ability to exclude Na+ and Cl− from its shoots and maintaining low (