Response of tossa jute (Corchorus olitorius L.) salt stressed plants to external application of calcium and potassium

This study focused on the improving effect of external application of calcium and potassium on growth, ions and organic solutes accumulation in tossa jute plants grown under salt stress. Young plants were subjected in pots to ten treatments including the control without NaCl, 120 mM NaCl and a combination of 120 mM NaCl and an addition of 40 or 60 mM CaSO4, CaCl2, K2SO4 or KNO3. Plant growth, sodium, potassium, proline and soluble sugars contents were determined after two weeks. Results revealed that only the external application of CaSO4 and K2SO4 at 40 mM significantly improved the growth reduction induced by NaCl followed by CaCl2; whereas at 60 mM, only CaSO4 induced similar changes in plant growth. Only, the exogenous application of calcium at 40 mM induced a significant decrease (p<0.05) in the Na+ content and a significant increase (p<0.001) of the K+/Na+ ratio of leaves in comparison with salt stressed plants, while the two forms of calcium and K2SO4 induced a significant increase (p=0.05) in the K+ content. CaSO4 had the best improving effects on plants growth under salt stress, followed by K2SO4 and CaCl2 at 40 mM. This improving effect is due to a better exclusion of Na+ from the leaves, the maintenance of a high ionic selectivity ratio K/Na and/or a better accumulation of K+.   Key words: Corchorus olitorius, sodium, potassium, calcium sulphate, calcium chloride, potassium sulphate, potassium nitrate, proline, soluble sugars.