Translocation and Storage of 14 C-labled Total Nonstructural Carbohydrates in Honey Mesquite

Abstract

Translocation of total nonstructural carbohydrates (TNC) in mature honey mesquite (Prosopis glandulosa var. glandulosa) trees was studied by photosynthetically incorporating 14 CO2 on eight dates during the summer of 1975. Several plant parts were analyzed for TNC and relative total activity (RTA) to determine direction of translocation and sink strength. Stem and twig TNC fluctuated more than basal bud TNC in response to phenological development. Pods were generally the strongest TNC sink except during initial pod formation (June 25), when bidirectional translocation occurred and all plant parts sampled contained equal concentrations of the 14 C label. A RTA/TNC ratio used in conjunction with RTA and TNC suggested that increased TNC concentrations in the pods and stems may not always be due to increased import of TNC but caused by a reduction in growth with constant importation. Greatest translocation of TNC to the basal buds occurred between the phenological stages of green flower spikes (June 10) and pod formation (June 25) and during pod maturation (August 4 to August 19).