Seasonal variations in the uptake of [32P]phosphate ions by excised ectomycorrhizae and lateral roots of Abies balsamea

The absorption of phosphate ions by long lateral nonmycorrhizal roots and by four of the most prevalent types of ectomycorrhizae of Abiesbalsamea was followed over one season of growth. For each experiment, the excised roots were bathed for 2.5 h in a buffered nutrient solution containing 100 μg•L−1 of KH2PO4 and 100 μCi•L−1 (1 Ci = 37 GBq) of KH232PO4. The results indicate that the rates of absorption of the different types of balsam fir root apices varied during the season and differed from one type to another. The surface of absorption appeared to have an effect on the amount of phosphate ions taken up from the solution. The rates of absorption measured invitro, seemed to reflect the seasonal absorption potential for phosphate ions by balsam fir roots invivo. It was clearly demonstrated that the most intensive rates of uptake occurred in mid-August immediately after bud set. The possibility that the absorption of phosphate ions is controlled by internal demand and is related to the translocation of car...