THE LONG-TERM EFFECTS OF NITRATE ON THE GROWTH AND NODULE STRUCTURE OF THE CAESALPINIOID HERBACEOUS LEGUME CHAMAECRISTA-FASCICULATA MICHAUX

Various nitrate concentrations (0, 1, 2, 4, 8, 20, 50 mol m-3) were ap plied at weekly intervals for 10 weeks to the caesalpinioid legume Cha maecrista fasciculata. Microscopic techniques and general growth studi es showed that nitrate affected both the plant and its rhizobial symbi osis. As the nitrate concentration was increased, nodule structure bec ame increasingly disrupted even though nitrate remained limiting to pl ant growth until 8 mol m-3. Poly-g-hydroxybutyrate (PHB) was observed using transmission electron microscopy; as nitrate increased from 0 to 2 mol m-3, the PHB stores were utilized.