The Partitioning of photosynthate to nodules and Nitrogen fixation in beans( Phaseolus vulgaris L)

This study was designed to determine the influence of the maturity status on partitioning of photosynthate to the roots and nitrogen fixation in common beans (Phaseolus Vulgaris L.). Two experiments(glasshouse at the University of Zambia and field at the Zambia Seed Company farm, Ngwerere, north of Lusaka) were conducted using a split –plot design in both cases. Three nitrogen treatments, i.e.-fertilized (80kgN/ha), inoculated with Rhizobium CIAT 899 (1ml of inoculum per plant in glasshouse and 2ml per hill in the field) and non-inoculated were the main plots. Six cultivars of beans each, two representing a maturing group; early (Chizi and Contender), medium (Kablengeti and CG 76-1) and late maturing (PVA 2280 and Carioca) were the sub plots. Parameters measured were nodule number per plant, nodule dry weight per plant, carbohydrate content in roots and shoot nitrogen content. The data were collected at three growth stages, i.e., 50% flowering, pod initiation and mid-pod fill. It was found that the maturity status of bean cultivar had no influence on the partitioning photosynthates to the roots; amount of nitrogen in shoots was positively correlated with carbohydrate content in the roots. This confirms that the supply photosynthates is very important in the roots.