EFFECTS ON YIELD AND NUTRITION OF MYCORRHIZAL AND NODULATED PUERARIA PHASEOLOIDES EXERTED BY P-SOLUBILIZING RHIZOBACTERIA

We studied the effect of bacteria involved in rock phosphate (four iso lates), iron phosphate (two isolates), and aluminium phosphate (two is olates) solubilization, and two phytate-mineralizing bacteria in terms of their interaction with two Glomus spp. on Pueraria phaseoloides gr owth and nutrition. The plant Rhizobium sp. - mycorrhiza symbiosis sys tem may increase in yield and nutrition in association with specific r hizosphere bacteria that solubilize calcium, iron, and aluminium phosp hates. No benefit from phytate-mineralizing bacteria was found under t hese experimental conditions. P. phaseloides growth responses were inf luenced in different ways by specific combinations of the selected bac teria and arbuscular mycorrhizal fungi. Considerable stimulation of nu trient uptake was observed with fungus-bacteria combinations of Azospi rillum sp. 1, Bacillus sp. 1 or Enterobacter (spp. 1 or 2) associated with G. mosseae. The fact that Bacillus sp. 1, a calcium-phosphate sol ubilizing isolate, positively interacted with G. mosseae and negativel y with G. fasciculatum is an indication of specific functional compati bility between the biotic components integrated in the system. From ou r results, the interactions between bacterial groups able to solubiliz e specific phosphate and mycorrhizal fungi cannot be interpreted as oc curring only via P solubilization mechanisms since no generalized effe ct was obtained. Iron-phosphate solubilizing microorganisms were more active alone than in dual associations with Glomus sp., but the alumin ium-phosphate dissolving isolates positively interacted in mycorrhizal plants. Further work is needed in this area in order to elucidate the mechanisms that affect rhizosphere microorganism interactions. G. mos seae was more effective but less infective than G. fasciculatum in mos t of the combined treatments.