Responses of Some Promiscuous and Nonprom Iscuous Soybean Cultivars to Inoculation and Phosphorus Application

Abstract

Pot and field studies were carried out at the University o f Ghana, Legon, to evaluate the effect of Bradyrhizobium japonicum inoculation and five rates of phosphorus application on growth, nodulation and dry matter production o f some promiscuous and non-promiscuous soybean cultivars in pots and finally the effect o f three rates of phosphorus and inoculation on growth, nodulation, dry matter production and yield of a promiscuous cultivar "Bengbie" in the field. In the pot experiment, one non-promiscuous cultivar (Davis) and two promiscuous cultivars (Bengbie and Anidaso) were inoculated with B. japonicum strain TAL 102 and also received 0, 8.9, 17.9, 26.8 and 35.7mg P/kg soil (equivalent to 0, 20, 40, 60 and 80kg P/ha.). Inoculation generally caused significant increases in nodulation, shoot dry weight, shoot nitrogen (N) and shoot (P), but not root dry weight. Phosphorus application on the average increased nodulation, root and shoot dry weight and shoot N and P. The non-promiscuous cultivar produced higher nodulation and shoot N than the promiscuous cultivars on inoculation. Interaction between inoculation and cultivar was significant for nodulation, root dry weight and shoot N while phosphorus and cultivar interaction was significant for shoot dry weight and shoot P. In the field experiment, one promiscuous cultivar "Bengbie" was inoculated with B. japonicum strain TAL 102 and given 0, 30 and 60 kg P/ha. Inoculation in the field increased nodulation, root dry weight, shoot N and shoot P. This indicates that promiscuous cultivars can benefit from inoculation. However, inoculation failed to increase pod number and final grain yield Phosphorus application up to 60kg/ha did not significantly increase nodulation, shoot and root dry weight, shoot N and P, 100 - seed weight and final grain yield.