The Translocation of 14C-photosynthate in Pisum sativum L.

Short-term studies were undertaken of source and sink relationships in Pisum sativum, cultivar Orfac, plants grown in a controlled environment. 14C-distribution assays were conducted after 24 or 48 h 14Cphotoassimilate translocation from a single leaf subtending either a vegetative or a reproductive node. The primary allocation of 14C-assimilate was achieved within 24 h: there was no significant secondary movement of 14C within the subsequent 24 h. The pod was strongly but not exclusively dependent on the subtending leaf. Out of the total 14C fixed by a leaf the proportion that was exported within 24 h was related to the 14C-sink capacity of the pods. A rapid non-combustive 14C-assay method is described whereby 14C-tissue fragments are rendered translucent prior to direct scintillation counting of the sample. In terms of cpm per mg obtained the latter method was comparable to a wet combustion method adapted for insoluble 14C-tissue.