Salt tolerance & protoplasmic salt hardiness of various woody & herbaceous ornamental plants.

The interest in salt tolerance of plants, especially those of economic importance, is increasing as more saline lands are brought under cultivation, and as saline irrigation waters add to the salinity of cultivated soils. Research relating to the survival and growth of plants growing on soils containing excessive soluble salts has left many problems unsolved. The task of obtaining and selecting plants which may not only survive, but grow and produce satisfactorily on saline soils, is a varied and complex one. Hayward and Bernstein (2) recognized that salt tolerance may involve climatic, edaphic, genetic, physiological, and pathological factors and their interactions. Salt hardiness of the protoplasm is perhaps the ultimate factor in salt tolerance of plants. Succulence, root distribution, andl other factors may also contribute to salt tolerance, often by delaying lethal, internal salt concentrations (5). Repp and her associates (6) reported a rapid tissue test for relative salt hardiness. Stem sections were inmmersed in a graded series of sodium clhloride solutions for 24 hours, after which their survival w\Nas tested by inmmersing them in hypertonic glucose solution. Cells wlhiicl became plasmolyzed were considered alive, while cells whichl couldl not be plasmolyzed w\ere considered dead. They found good correlation betwreen the salt hardiness of the protoplasm an(l salt tolerance of a number of plants. Van der Zweep (9) used plasmolytic studies in conjunction with tetrazolium for checking phytotoxicity of certain hydrocarbons on plants. He fon(nd that one technique substantiated the other. Since a better or easier technique is neecled to interpret cell vitality after exposure to Repp's sodium chloridle solution technique, tetrazolium was also employe(d in this studv. Of all plants studied thus far in relation to salt tolerance, ornamental plants. especially trees, have received relatively little attention; y-et there is an increasing demand for practical as well as technical information concerning these plants. In this study the protoplasmic salt har(liness of a number of ornamental species w-as measured by