The effect of rhizobial inoculation, phosphorous and molybednum application on nodulation, nitrogen fixation and yield of kidney bean (Phaseolus vulgaris L)

The effect of rhizobial inoculation, phosphorus and molybdenum application on bean (Phaseolus vulgaris L. cv. Canadian (wonder) was investigated in the glasshouse and field, using a completely randomized design and a completely randomized block design respectively. In the glasshouse experiment, inoculation significantly increased nodulation and nitrogenase activity but significantly decreased shoot dry weight and total nitrogen of the shoot. There was a significant positive interaction between inoculation and molybdenum on nodule dry weight, shoot dry weight and nitrogen content of the shoot, but the interaction between inoculation and phosphorus or nodule dry weight and nitrogen content of the shoot was nor-significant.There was none or very low nitrogenase activity in the uninoculate plants while activities as high as 2.037 ymol N/plant/hr were recorded in the inoculated plants. Phosphorus and molybdenum application had no significant effect on nodulation but increased shoot dry weight and total nitrogen of the shoot. There was a significant positive interaction between phosphorus and molybdenum on shoot dry weight. The field grown beans did not nodulate, though inoculation gave an apparent increase in shoot dry weight and nitrogen content of the shoot. Phosphorus and molybdenum application increased shoot dry weight and nitrogen content of the shoot. The grain yield was significantly increased by phosphorus, but reduced by molybdenum.The optimum level of phosphorus appears to be between 25 and 50 kgP/ha. It has been concluded that bean yield can be improved by phosphorus application and areas that require futher researen have been suggested.