Effects of Penicillium bilaii on maize growth are mediated by available phosphorus

Abstract

Inoculation with Penicillium bilaii has been reported to increase plant growth, which is attributed to increase availability of phosphorus (P), but similar effects have been observed with no P limitation, suggesting that other mechanisms may be involved. The aim of this work was to evaluate the interaction between available soil P and P. bilaii inoculation on plant growth. Maize plants (Zea mays) inoculated with P. bilaii and non-inoculated were grown in pot experiments in three soils with different inherent P availability, and in a low P availability soil with different additions of mineral P, both with and without supplementation of all other macro and micronutrients. We found a positive interaction between P bilaii and available P, when other nutrients were applied, with P bilaii inoculation resulting in increased root growth and thus nutrient uptake and plant growth. By contrast, when other nutrients were not supplied, little effect on plant growth or P uptake was observed, except for root length that tended to decrease in inoculated plants with P addition. The effects of P. bilaii inoculation were related to root growth and function, but were dependent on the nutrient status in the soil environment.