STUDIES ON THE SALT TOLERANCE OF SOME HALOPHYTES IN THE SUDAN

This study is centered on screening the response of Sporobolus spicatu s (Vahl) Kunth, Suaeda monoica Forsk. and Zygophyllum album L. to sali nity. The plants were subjected to different concentrations of artific ial sea water which contains NaCl as the main component. The concentra tion of artificial sea water ranges between 0.0 - 6.0%. NaCl concentra tion in the solutions varies between 0.0 - 1026.7 mol m-3. The general growth of the three halophytes relates mainly to salt concentration. The optimum salinity for their development has been established at 0.5 - 1.5% (85.6 - 256.7 mol m-3 NaCl) for Sporobolus spicatus and 0.5 - 1.0% (85.6 - 171.1 mol m-3 NaCl) for Suaeda monoica and Zygophyllum al bum. Hence, these three species are obligate halophytes. Suboptimal an d excessive salt concentrations result in a general decline of the veg etative parameters e.g. fresh and dry weights and crude fibre. Chlorid e uptake induces salt secretion on the shoot system of Sporobolus spic atus a mechanism to get rid of the excess salt and adjust the plants o smotic pressure, characteristic of a pseudohalophyte. The overall chlo ride content within the tested plants and precipitated on Sporobolus s picatus tissues is directly proportional to salt concentration. The hi ghest chloride uptake by the three halophytic plants was encountered a t 4.5 - 6.0% and the least at the salt-free substrate. The mechanism i nvolved in salt tolerance is based on salt secretion on the shoots of Sporobolus spicatus and succulence in Suaeda monoica and Zygophyllum a lbum i.e. euhalophytes.