The influence of nitrogen source and Rhizobium seed inoculation on growth, yield and quality of french beans (phaseolus vulgaris (l.)

Abstract

Field studies were conducted between august, 1987 and January, 1988 at the Field Station, Faculty of Agriculture, University of Nairoi, Kabete to show the effects of fertilizer nitrogen sources (Diammonium phosphate – DAP and Calcium ammoniun nitrate –CAN) and Rhizobium seed inoculation on growth, yield and quality of French beans (Phaseolus bulgaris), Cvs, ‘Monel’ and ‘Finbel’. Nitrogen fertilizers were applied at the rate of 200 kg CAN or DAP/ha and a mixture of Rhizobium leguminosarum biovar phaseoli strain NUM 445+446 was used as the seed inoculant. A treatment where seeds were not inoculated and no fertilizer was included as a control. The total dry matter production in the French bean plants ws mainlu due to accumulation of dry matter in the leaves and stems. The use of inoculated seeds and applying DAP at planting resulted in ‘Monel’ plants accumulating significantly higher total dry matter than those from inoculated seeds top dressed later with CAN, CAN top dressing alone or the control. The total dry matter production was increased by 85% compared to the control. Application of DAP at planting followed later with CAN top dressing resulted in a total dry matter production and cumulative leaf area that were significantly higher than that of ‘Monel’ plants from inoculated seeds top dressed later with CAN, inoculated seed alone or the control. The total dry matter production and cumulative leaf area increase were 70.5% and 105.5% over the control, respectively. Similarly, using inoculated seeds and applying DAP at planting resulted in ‘Finbel’ plants accumulating significantly higher total dry matter and leaf area thant those from inoculated seeds top dressed later with CAN, inoculated seeds alone or the control. The total dry matter production and leaf area increase wwere 154.7% and 112.5% over the control, respectively. Application of DAP at planting followed later with CAN top dressing resulted in Finbel plants with significantly higher cumulative leaf area than those from inoculated seeds alone or the control. The cumulative leaf area was increased by 107.3% compared to the control. The total, marketable pod yields and quality were not significantly increased by the N-sources and Rhizobium seed inoculation. Application of DAP alont at planting using inoculated seeds and applying DAP at planting followed later with CAN top dressing or top dressing plants from inoculated seeds with CAN resulted in ‘Monel’ plants producing significantly higher number of pods than using inoculated seeds alone. The effect of N-sources and Rhizobium seed inoculation on the nodulation of French beans was not significant. However, the results indicated that using inoculated seeds and applying DAP at planting had a favourable effect on nodulation compated to CAN top dressing.