IMPROVING RHIZOBIUM INOCULATION IN-EFFICIENCY BY CO INFECTION, GROWTH AND N, P, K UPTAKE OF COWPEA (Vigna unguiculata L. WALP.)

The research aimed to study effect of mixedinoculation in promoting growth, efficiency of Rhizobium bacteria for purpose of infecting plants, enhancing growth, yield of cowpea plant and uptake of nitrogen, phosphorus and potassium. The idea of research was based on principle ofbenefiting from positive role of microbial interaction in the soil. The study included use of a Rhizobium isolate isolated from root nodules of cowpea plants (isolate R6).

The mixed inoculation treatment of Rhizobium, Pseudomonas, and Mycorrhizae I7 were exceeded of single and double inoculation treatments with microorganisms in increasing dry weight, number of root nodules and concentration of nitrogen and potassium in cowpea plant.

2- The necessity of inoculating cowpea with Rhizobium bacteria alone or in combination with Pseudomonas and Mycorrhizal or mixed inoculate in order to promote plant growth and the formation of root nodules.

3- The mixed inoculation treatment (I7 + N3 + O1) did not differ significantly with treatment (I7 + N2 + O1) in some of the studied parameters, such as dry weight, number of root nodules, nitrogen and potassium which reduced the recommendation of nitrogen fertilizer by 25 %, saving 10 kg N ha-1 and leading to reduce the cost production and reduced environmental pollution resulting lesse addition of fertilizer.