Neutron radioactivation analysis of plant leaves. What are known from the contents of elements

The contents of elements in plants are different according to parts, such as leaves, roots, stems, wooden part and so on. In the case of obtaining the information on the contents of elements in various kinds of plants, it is necessary to select mutually comparable parts. As such comparable parts, leaves which are common in trees and grasses seem useful, but the contents of elements in leaves are possible to change as the age of leaves advances, therefore, attention must be paid to the time of sampling and the age of leaves. It was decided to investigate first how the contents of elements change with the advance of the age of leaves. The objects were American dogwood growing in Kyoto Botanical Garden, and two adjoining trees and one tree at 150 m distance from them were selected. Leaves were sampled from the tree tops and side branches. The analyzed elements were K, Ca, Mg, Fe, Mn, Cu, Zn, B and Al. The contents of elements in leaves varied by seasons, and also the effects according to the parts of sampling and the places of growth were observed. July when leaves are ripe is suitable as the time of sampling leaves. The search for metal deposits by utilizing plants is mentioned. (K.I.)