investigation about ameliorative effects of CaCl2 and CaSO4 on growth, solouble proteins, soluble sugars, prolin and mineral nutrients in tomato plant (Licopersicum esculentum var Mobile)under salt stress _

Abstract

Salinity is the major environmental factor limiting plant growth and productivity. Tomato (Lycopersicon esculentom) is moderately tolerate to salinity(1/3ds/m>EC>6/1ds/m) but high salt significantly reduces crop productivity. The ability of plants to tolerance salt is determined by multiple biochemical pathways that facilitate retention and/or acquisition of water and maintain ion homeostasis. Essential pathways include those that lead to synthesis of osmotically active metabolites(e.x proline) and accumulate them especially in the cytoplasm.The other side it has been reported that calcium ameliorate detrimental effects of salinity stress. In order to study the effects of calcium on growth, compatible solutes and mineral nutrients of tomato plants leaves( Lycopersicon esculentom v. mobile) grown under salt stress,an experiment was arranged as a factorial experiment, based on completely random design with three replicates. The salt levels included NaCl solutions with electrical conductivity, 0, 8, 10,12 and 14 ds/m . Calcium used as CaCl2 and CaSo4(5mM). The plants were grown hydropunically in Hogland s solution. After eight weeks shoots were harvested and shoot dry weights, solouble proteins, solouble sugars, proline and mineral nutrients(sodium, potassium and calcium) in leaves were calculated. The results showed that increasing of salinity (particularly EC=10ds/m)signifficantly decreased shoot dry weights. Salinity was raised Na+ concentration and decreased K+and Ca+2 concentration in the leaves.The other side salt stress significantly increased soluble proteins, soluble sugars and proline in leaves. Calcium treatment ameliorated growth and these negative effecs with reducing Na+ uptake , increasing K+and Ca+2 uptake and also exciting synthesis and accumulate proline. It seems that calcium plays an essential role in alleviating injury of salinity with membrane stability and maintaining membrane permeability and could offer an economical and simple way in ameliorating adverse effects on tomato crop production problems caused by high salinity.