Enhanced Phytoremediation Of Olive Mill Wastewater "Zibar" Using Plant Growth Promoting Rhizobacteria (PGPR) With Barley and Clover

Olive mill wastewater (OMWW) has negative environmental impact. Utilization of OMWW in irrigation is difficult due to the toxic effect. Different phytoremediation methods were used to improve the use of OMWW in irrigation. In this research, PGPRs were implemented to investigate their efficiency of improving the phytoremediation technique for plants irrigated with olive mill waste water. Two strains of PGPR (UW3, Pseudomonas putida(A). UW4, Pseudomonas putida(C) with unassigned one (B)) were used with Barley (Hordeum valgare L.) and clover plants (Trifolium sp.). All trials were carried in a designed green house in faculty of agriculture at An-Najah national university in Tulkarem for 30 days. Plants irrigated with different concentration of OMWW (0%, 10%, 25%, and 50%). Seeds of both barley and clover irrigated by different concentration of olive mill waste water, showed significant differences in germination among the concentration levels of OMWW. It was notable that the OMWW has negative impact on seed germination of both plants. Neither barely nor clover plants treated with PGPRs had significant improvement in biomass compared with those irrigated with fresh water. Root length was decreased significantly with the increase of OMWW levels (57.8 and 58.5cm respectively). The OMWW application significantly reduced the shoot length. OMWW at 50% reduced the stem length (15.5 cm). A similar trend was observed with other measures (both fresh and dry weight of the plant). OMWW application was highly reduced both weights of stems and roots of both plant species. For clover plants, root length, shoot length, wet weight (P=(0.0057- 0.0001), were reduced, however, total dry weight, dry weight of roots, and dry weight of shoots (p< .05). The higher root length was observed with the control and 10% OMWW (25.22and 23.98 cm, respectively). Regarding shoot, shoot length was reduced, the lowest shoot length was observed (4.879) at 50% zibar application. Wet weight of clover was differs significantly among the different concentration of OMWW and different type of bacteria used. Pulse Amplitude Modulation (PAM) fluorometry showed no improvement in photosynthesis. Barely plants their values of Fv/Fm were ranged from (0.55 -0.68), which mean that plant is under stress, and its photosynthesis not proceed as it should be, and NPQ values ranged (0.11-0.17). The same was for clover plants treated with PGPR (UW3), irrigated with fresh water, 10% concentration of OMWW, values of Fv/Fm are closed to 0.8 and NPQ are decreased to .07.Other Trails of clover plants values of Fv/Fm were ranged from (0.62 -0.70), and NPQ values ranged (0.04-0.16).Which mean that plant is under stress, and its photosynthesis not proceed as it should.