This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via CrossRef Citing Articles via Web of Science (9) Citing Articles via Google Scholar Google Scholar Articles by Hutchin, M. E. Articles by Vaughan, B. E. Search for Related Content PubMed PubMed Citation Articles by Hutchin, M. E. Articles by Vaughan, B. E. Agricola Articles by Hutchin, M. E. Articles by Vaughan, B. E.

Articles

Relation Between Simultaneous Ca and Sr Transport Rates in Isolated Segments of Vetch, Barley, and Pine Roots ¹

Biological and Medical Sciences Division, United States Naval Radiological Defense Laboratory, San Francisco, California 94135

Root segments of vetch, barley, and pine were exposed to a nutrient solution containing ⁸⁵Sr and ⁴⁵Ca tracers. Translocation was measured from solutions containing stable ions at concentrations of 2.5 mM Ca, and at either 0.5 mM or 2.5 mM Sr. Polar transport was established between 12 and 18 hr in barley, and between 16 and 22 hr in vetch. Acropetal transport remained below 5% of basipetal transport of tracer during these intervals. Transport in both vetch and barley usually declined before an elapsed time of 24 hr unlike corn, which maintained its steady state beyond 24 hr. Pine was radically different in that it showed no difference between acropetal and basipetal transport rates and had very low rates. Sr transport in all plants studied to date paralleled that of Ca and the ratio Sr:Ca transported was equal to the ratio Sr:Ca in the nutrient. In vetch, stable Ca transport was reduced to one-fifth when Sr concentration was increased from 0.5 mM to 2.5 mM. Yet stable Sr transport did not change, indicating that the effect on transport was not due to competitive inhibition. A similar effect was less pronounced in barley, but could not be detected in pine. The magnitude of the transport rates varied considerably among the various species, corn having the greatest followed by barley, vetch, and pine in decreasing order. Transport did not correlate with root weight or surface area; it amounted to from 0.03 to 0.60 nanomoles per hr in these experiments as compared to 7 nanomoles per hr previously established in corn (in all cases, 55 mm segments, sectioned 10 mm from apex).