
%0 Journal Article
%A Winter, E 
%A Preston, J 
%T Salt Tolerance of <I>Trifolium alexandrinum</I> L. IV. Ion Measurements by X-Ray Microanalysis in Unfixed, Frozen Hydrated Leaf Cells at Various Stages of Salt Treatment
%J Functional Plant Biology
%D 1982/04/01
%V 9
%N 2
%P 251-259
%K 
%R https://doi.org/10.1071/PP9820251
%U https://www.publish.csiro.au/paper/PP9820251 
%X Bulk-frozen leaf tissue of salt-treated (50 mM NaCI) T. alexandrinum plants harvested at various stages of the salt treatment was fractured in a scanning electron microscope. By means of X-ray microanalysis, Na+ and Cl\- was measured in single cells of the veins and of the surrounding tissue. From the corrected peak values Na+ : K+ ratios were calculated for each cell. For each sampling interval the average percentage of cells falling into various categories of Na+ :K+ and CI- :K+ was determined in all tissues. In the phloem parenchyma the percentage of cells having a very high Na+ :K+ ratio (>4) rose between days 10 and 16 of the salt treatment, whereas the percentage of xylem parenchyma cells falling into this category declined. It is concluded that the increasing Na+ :K+ ratios in the phloem are the result of both an enhanced inflow of Na+ into the veins (measured in a previous experiment) and the retranslocation of Na+ from the xylem to the phloem. The results support the hypothesis of intraveinal recycling of Na+ in salt-stressed young leaves of T. alexandrinum and may explain the gradual damage to the phloem transfer cells observed with progressive salt treatment. 
