Alleviation of Salt Stress by Phosphorus in Cucumber Microshoots Grown on Rooting Medium

The goal of this work was to test the in vitro responses of cucumber microshoots to salt stress as affected by increased phosphorus (P) in the medium. Salt stress was induced by incorporating different levels (0.0, 25, 50, 75 and 100 mM) of NaCl to the medium. Increased P in the medium was efficient to ameliorate the adverse effects of salinity. Shoot and root growth of cucumber microshoots were negatively affected by salt stress, whereas increasing P improved their growth with elevated NaCl levels. NaCl-induced salt stress reduced (more negative) leaf cell sap osmotic potential of cucumber microshoots which was increased (less negative) by P treatments. Total protein content was reduced and proline was accumulated as a result of in vitro induced salt stress. However, increased P concentration in the medium enhanced the microshoots content of protein and lowered their content of proline. The microshoots content of K, Ca and P were reduced by salt stress and this reduction was less as P concentration increased in the medium.