Abstracts |
A study was conducted to investigate the effect of arbuscular mycorrhizal fungi and rhizobia under different concentrations of zinc (0, 50, 100, 200, 500 and 1000 mg/kg) and cadmium (0, 5, 10, 20, 50 and 100 mg/kg) on the growth and some metabolic activities of Vigna sinensis [V. unguiculata]. Also, the effect of both heavy metals on mycorrhizal development and nodulation was evaluated. Results showed a decrease in germination percentage of vigna seeds with the increasing application rates of Zn and Cd. Dual inoculation with mycorrhiza and rhizobia increased plant height and root length while high levels of Zn and Cd decreased leaf area. Inoculated plants were more tolerant to Zn and Cd compared to those uninoculated. Low Zn levels improved plant growth, and inoculation increased chlorophyll content at all treatments. However, pigments decreased at high levels of both Zn and Cd, mycorrhizal colonization and nodulation improved nitrogen and phosphorus uptake by vigna plants at all treatments, also plant uptake were affected by soil application with Zn and Cd. Carbohydrates were enhanced by mycorrhizal and rhizobial inoculation, but decreased with increasing rates of Zn and Cd in soil. Inoculations contribute to the accumulation of Zn and Cd in vigna roots, as well as reducing both metals transfer to plant shoots. Zn and Cd application reduced mycorrhizal root infection and nodulation, which clearly indicated that plants were more sensitive to lower Cd levels than Zn. |