204 SHORT COMMUN.CALION Tatl: |, Comparative uptake of different radwenuclides by vean plants. Duration of treatment in labelled nutraad solution 2 15 ays Uptake Radionuclide mri NOR atop); alep, Sr Lis.d. (p= 0-05) Concentration factor Transport Roo index % uf added Shoots Roots Shoots 0-09 9-61 0-29 0-06 8-77 2:06 76:35 36-98 90-64 68-01 2-80 20-05 0-91 84-60 2-69 0-58 83-14 5-83 4185 1787 4246 3324 142 1217 0-12 20-62 0-32 0-09 75-82 —_ Radionuclide content/g plant tissue *Concentration factors --— -- —-—— - -~- Radionuclide content/ml nutrient solution. t Transport index = Shoot conter content| A Total plant content times greater. Further, the amount of radium translocated to shoots is comparable to that of strontium. likely to be influenced by various factors which transfer of ***Ra to shoots suggests that among Acknowoledgement—The autbors are grateful to Dr. The present evidence of relatively rapid the nuclides examined here ™*Ra is likely to make the major contribution to radioactivity in aerial tissues of plants grown under condi- tions where root absorption is the principal route ofentry ofthe nuclides. In situations where plant organs are subject to considerable atmospheric washout of “Rn daughter products, however, higher concentrations of ™*Ph and °Po than "*Ra may be obtained. It has been reported by Marneorp ef al.,(% Ersensup ¢f af. and Mistry ot al.that the contribution of radium isotopes to the alpha activity found in the stem, leaves and fruits of plants growing in the uranium and thorium tich high background radiation areas far exceeds that of thorium isotopes. The present findings from nutrient culture experiments are compatible with the above reports. When plants are grown in soil containing uranium series nuclides theie accumulation in roots is considerably lower than that in roots of plants grown in labelled nutrient solution as a result of the great affinity of these nuclides for exchangesites on the soil.@.**19 Furthermore, comparative uptake of the nuctides from soil is control their availability in the soil. In future we plan to examine the uptake of these radionuclides by plans from contrasting soil types. A. R. Gopat-Avznaar for his encouragement and interest. “ Biology Division Bhabha Atomic Research Contre T. J. D’Souza K. B. Misray Trombay, Bombay, India REFERENCES 1. D'Souza T. J. and Mrsray K. B. (1966) Prelininary studies on the absorption and translocation of *#*Po and ***Pb by plants. Pree. All India Symp. Radioactis. Maetrel. Ratieand. Bombay, 381-40. 2. Emansup M., Pernzow H., Dusw R. T., Rosen F. X., Keozt G. and Curren T. L. (1963) Naturally occurring radionuclides in foods and waters from the Brazilian aress of high radio- activity, pp. 854-854. fe J. A. S. Apass and W. M. Lowner (Eds.), The netwal radiation ervironment. University ofChicago Prem, Chicago. 3. Giuree K. B. and Murray K. B. (1970) The effect of chelating agents on the absorption of radigen by plants, Plant ead Sel 32 (in prea).