Uptake and translocation of Mn-54 and Zn-65 applied on foliage and bark surfaces of balsam fir [Abies balsamea (L) Mill] seedlings

Uptake and translocation of Mn-54 and Zn-65 in balsam fir [Abies balsamea (L.) Mill.] seedlings were studied with the radioisotopes applied directly on shoot or main-stem surfaces in a growth chamber. Concentration and distribution of the absorbed radioisotopes in different plant parts depended on distances between source (the application site) and sink (the rest of the seedling), as well as on tissue growth activity. Acidic wetness significantly enhanced radioisotope absorption. Mn-54 and Zn-65 were found to be concentrated primarily in 1-year old needles at the middle and top levels of the seedling crown. There were significant (P < 0.05) differences in accumulation (Bq g-l) between Mn-54 and Zn-65 in needles and twigs from foliar uptake. The absorption by seedlings (including the washed application shoot) 70 days after application was 24-32% of the remaining activities for Mn-54 and 25-30% for Zn-65. Less than 1% of the absorbed isotopes was translocated from the bark application sites to other plant organs, whereas more than 54% of the activity absorbed at 1-year old shoots moved to the rest of the seedling.