Mitigation effects of Rhizophagus intraradices and Micrococcus yunnanensis on boron toxicity in maize (Zea may L.) plant

Abstract

A greenhouse pot experiment was conducted to investigate the effect of arbuscular mycorrhiza fungus and plant growth promoting rhizobacterium on maize (Zea may L.) growth as well as nutrient concentrations under different levels of boron (B). Five levels of B (0, 10, 20, 40 and 60 mg B kg−1 as boric acid) and four levels of microbial inoculants (non-inoculation, Rhizophagus intraradices, Micrococcus yunnanensis, and co-inoculation) were used. Shoot and root dry weights significantly decreased as B levels increased. An increase in plant growth was observed at the levels of 10 and 20 mg B kg−1 due to microbial inoculation especially mycorrhization. Shoot and root dry weights positively correlated with shoot phosphorus concentration and root colonization. At the level of 40 mg B kg−1, root colonization significantly decreased. Shoot iron, copper, sodium and zinc concentrations significantly increased under excessive B concentrations. Totally, B application at low quantity improved plant growth while at higher rates it seemed toxic. Nonetheless, the inoculation of bacterium and arbuscular mycorrhiza had a more alleviative effect when the plant was exposed to excess B.