Revegetation of barren lakeside land through growth enhancement of Xanthium italicum by rhizobacteria

Abstract

The plant growth promoting capability of rhizobacteria was examined for revegetation of a barren lakeside through growth enhancement of a wild plant. Over 100 bacterial strains were isolated from the rhizospheres of two wild plant species on a barren lakeside. Among them, three strains, Arthrobacter humicola AG, Arthrobacter woluwensis ED, and Acinetobacter guillouiae D-KI, showed efficient effects for plant growth promotion. They produced large amounts of phytohormones such as indole-3-acetic acid, indole-3-butyric acid, gibberellin, zeatin, and abscisic acid. They also produced >200 mg l−1 of soluble phosphates from insoluble calcium phosphate within 2 days. Their effect on plant growth promotion was tested in a microcosm composed of soil collected from the barren lakeside of Lake Paro, Korea and sown with seeds of a wild plant, clotbur (Xanthium italicum), which may act as a pioneer species on barren lands. When they were inoculated into the microcosm, all three strains enhanced the growth of X. italicum plants compared to the uninoculated control during the 4 week period. Among the three strains, A. humicola AG showed the highest increases in length and dry weight of plant roots (41.7 and 61.0 %, respectively) compared to those of the uninoculated control. A. woluwensis ED increased root length and dry weight of shoots and roots of X. italicum by 12.1, 21.7, and 49.2 %, respectively. The growth-promoting effect of X. italicum by rhizobacteria could be utilized for revegetation of barren but sensitive lakeside land.