The contents of some hitherto not reported trace elements in phloem exudate from Yucca flaccida Haw., determined by means of non-destructive neutron activation analysis

In previous papers on phloem exudate from Yucca flaccida inflorescences the concentrations of several trace elements have been reported (Tammes & Van Die 1966; Van Die & Tammes 1975). The present communication reports the contents of 14 elements, 6 of which so far were unknown to occur in sieve tube exudates in general (Ziegler 1975), whereas that of one other element, viz. chlorine, in Yucca flaccida phloem exudate was relatively roughly estimated only. Nine samples of phloem exudate, at irregular intervals of time collected from a single bleeding plant, were used. Six of them were analyzed in duplicate. The fifteen 1.0 ml aliquots taken from these samples were pipetted into special polyethylene capsules with low trace-element levels, freeze dried during 24 h, weighed, and subjected to instrumental, non-destructive, neutron activation analysis as described by De Bruin & Korthoven (1972,1974), and Korthoven & De Bruin (1977). The measurements were carried out at the Interuniversity Reactor Institute (IRI), Delft.