ENHANCING THE GROWTH OF VICIA FABA PLANTS BY MICROBIAL INOCULATION TO IMPROVE THEIR PHYTOREMEDIATION POTENTIAL FOR OILY DESERT AREAS

摘要

Two experiments were conducted to investigate the effect of inoculating Vicia faba plants (broad beens) raised in clean and oily sand with nodule-forming rhizobia and plant-growth-promoting rhizobacteria (PGPR) on growth of these plants in sand and totest whether this can improve the phytoremediatioii potential of this crop for oily desert areas. It was found that crude oil in sand at concentrations <1.0% (wlw) enhanced the plant heights, their fresh and dry weights, the total nodule weights per plant, and the nitrogen contents of shoots and fruits. Similar enhancing effects were recorded when roots of the young plants were inoculated with nodule bacteria alone, PGPR alone, or a mixture of one strain of nodule bacteria and one of the PGPR. Such plant growth effects were associated with a better phytoremediatioii potential of V. (aba plants for oily sand. The total numbers of oil-utilising bacteria increased in the rhizosphere and more hydrocarbons were eliminated in sand close to the roots. The nodule bacteria tested were two strains of Rhizobium leguminosarum and the PGPR were Pseudomonas aeruginosa and Serratia liquefaciens. The four strains wefe found to use crude oil, n-octadecane, and phenanthrene as sole sources of carbon and energy. It wasconcluded that coinoculation of V. faba plant roots in oily sand with nodule bacteria and PGPR enhances the phytoremediation potential of this plant for oily desert sand through improving plant growth and nitrogen fixation.