Use of iso-osmotic solution to understand salt stress responses in lentil (Lens culinaris Medik.)

Lentil, an important source of protein for human consumption, is considered as a salt susceptible crop species. Thus the present study was carried out to evaluate the most important lentil physiological characters that induce salt tolerance. Salt stress results in osmotic stress immediately followed by ionic toxicity. We used iso-osmotic solutions with different kinds of osmotica i.e. salt (NaCl and KCl), and polyethylene glycol (PEG) to identify the specific response of osmotic stress and ionic toxicity. All of these altered seedling height, chlorophyll, malondialdehyde (MDA), hydrogen peroxide (H2O2), proline, reduced ascorbate (AsA) and total glutathione content, and ion uptake. Moreover, these osmotica also altered the activities of antioxidant enzymes such as catalase (CAT), ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR) and glutathione reductase (GR), except monodehydroascorbate reductase (MDHAR). Among different osmotica, only NaCl exhibited leaf chlorosis, reduction in K+ and disruption in ion homeostasis, and increased MDA, H2O2 and proline content than iso-osmotic KCl and PEG, indicating susceptibility of lentil seedling to salt stress. Addition of Ca along with NaCl showed no chlorosis and improved K+ content. These results demonstrate that prevention of Na-induced K depletion in root might enhance salt tolerance in lentil.