Seed inoculation with Penicillium bilaiae and Bacillus simplex affects the nutrient status of winter wheat

Abstract

Penicillium bilaiae is a P-solubilizing fungus that is used as an inoculant to promote plant growth or P uptake in various crops. Bacillus simplex has also been shown to have positive effects on different crops. However, the interaction between these inoculants and their effect on plant growth and acquisition of nutrients other than P are poorly understood. In two pot trials at different levels of inorganic P fertilization, we investigated the effect of single and combined inoculation with Penicillium bilaiae and Bacillus simplex on the growth and nutrient status of winter wheat (Triticum aestivum L.), as well as inoculant persistence and colonization. Quantitative PCR analyses revealed that both inoculants colonized and persisted on seeds and roots. The microbial inoculants increased the P concentration in root biomass at all P levels and concentrations of Mg, Mn and S in shoot biomass in low-P soil, without however having any significant effect on plant growth. Furthermore, unlike the single inoculations, the combined inoculation increased P uptake in low-P soil. These results indicate that use of the studied microbial inoculants has the potential to improve the nutritional status of winter wheat in low-P soil, especially when applied as a consortium.