Nitratreduktase-Aktivität in Blättern und Früchten verschiedener Leguminosen

Abstract

Changes in the nitrate reductase activity of legumen leaves and fruits have been investigated in respect to ontogenetic development, diurnal rhythm, and parts of leavels and fruits. Pericarps of the fruits belonging to the taxon Phaseoleae exhibit a pattern of the nitrate reductase activity in basal middle, and apical zones of this organ to that different of the Vicieae. No corresponding zones of different nitrate reductase activity have been observed in the leaves of these species. Leaves of Phaseolus vulgaris and Vicia faba, respectively, exhibit a diurnal rhythms of nitrate reductase activity, whereas in the pericarps and seeds of Vicia faba, the only species of which fruits have been investigated, no diurnal rhythm in nitrate reductase activity has been found. During leaf ontogenesis a maximal nitrate reductase activity per g fresh weight is reached just before or at the time of full expansion of this organ. Subsequently nitrate reductase activity decreases and remains nearly constant until senescence becomes obvious by the yellowing of the leaves. On the basis of the ontogenetic changes of the nitrate reductase activity in the inidvidual leaves the pattern of maximal nitrate reductase activities within one plant is investigated by comparing leaves of different developmental stages.