Effects of Biochar and AM Fungi on Growth, Mineral Elements and Cadmium Uptake of Mulberry under Cadmium Stress

Abstract

In order to explore the synergistic effect of biochar and arbuscular mycorrhizal (AM) fungi on plant growth under cadmium (Cd) stress, a pot experiment was conducted to investigate the effects of biochar application and AM fungal inoculation on mulberry (Morus alba) seedling growth, mineral element absorption, Cd uptake, soil pH and Cd availability under Cd contamination at 2 levels (0 and 4 mg⋅kg−1). The results showed that biochar application could increase the mycorrhizal infection rate of AM fungi. Biochar application and AM fungal inoculation alone or their combination could all increase plant height, biomass, mineral element content and soil pH, while reduce Cd bioavailability in soil and Cd uptake by mulberry seedlings. The effects of biochar application in increasing soil pH and N and K uptake were better compared with AM fungal inoculation. However, AM fungal inoculation presented better effects in promoting mulberry seedling growth, improving P, Ca and Mg absorption by mulberry seedlings, and reducing Cd availability in soil and Cd absorption by mulberry seedlings. The combination of biochar application and AM fungal inoculation obtained the best effect. Under Cd level of 4 mg⋅kg−1, the combination of biochar application and AM fungal inoculation increased plant height and N, P, K, Ca and Mg contents in mulberry leaves by 43.28%, 125.56%, 178.48%, 3.63%, 181.04% and 128.04%, respectively. While, Cd concentration in the roots, stems and leaves of mulberry seedlings decreased by 46.48%, 67.86% and 58.97%, respectively. Moreover, pH increased by 5.33%, while Cd availability in soil decreased by 69.53%. In conclusion, biochar and AM fungi alone or their combination can all reduce Cd stress, and promote plant growth and mineral element absorption. The combination of biochar and AM fungi presents the best effect. Biochar combined with AM fungi can be used as an effective measure for ecological restoration of degraded soil and agricultural production safety.