The response of small white bean (Phaseolus Vulgaris L.) to different nitrogen and molybdenum fertilizer applications

Dry bean production is normally associated with high soil fertility rich in organic matter content. However, dry beans are not exhibited dramatic improvements of seed yield through the development of high yielding cultivars, improved cultural practices and the use of external inputs, especially fertilizers when compared to other crops. The current acute bean shortage resulted in the need for better production systems to increase yield through fertilization. This study was therefore conducted with the objectives of investigating the role of N and Mo fertilizers in determining the growth and yield of beans, the different rates of N in band and broadcast placement methods that can give optimum yield, and the amount of total protein and total Mo found in the dry seeds as a result of the applied fertilizers. Two separate pot experiments of band and broadcast placement of N in different rates with and without Mo were executed during 2000/2001 growing season in the glasshouse at the University of the Free State, Bloemfontein, South Africa. Each pot was filled with red brown soil and planted to a dry bean cultivar, PAN 181. The plant density was maintained at three plants per pot. A completely randomized design with factorial combination consisting of four N levels (0, 20, 40 and 60 kg N ha") and three Mo treatments (0, 100 g Mo ha" leaf spray and 100 g Mo ha" seed treatment) replicated four times was used in the experiment. The results obtained indicated that the application of N and Mo fertilizers did not significantly affect the vegetative growth as well as the reproductive development of the tested dry bean cultivar. However, the application of N in band placement with Mo treatments affected seed yield more than the broadcast placement. With the band N placement method, higher seed yield was achieved at 60 kg N ha" with seed treated Mo while that of broadcast N placement was at zero N with seed treated Mo. With regard to the nutrient content of the dry seeds, higher seed total protein was obtained at 60 kg N ha" with zero Mo in banded N and at zero N with seed treated Mo in broadcasted N. Higher seed Mo content was achieved at 60 kg N ha" with seed treated Mo in band N placement whereas in broadcast N placement it was at zero N with seed treated Mo. Finally, further field trials are recommended in order to verify the glasshouse results under field conditions.