Impact of a wood-based biochar in peat-reduced and peat-free substrates on strawberry cultivation and rhizosphere microbiome dynamics

Abstract

A disadvantage of soilless cultivation is the use of peat, which contributes to CO2 emissions. Biochar addition to horticultural substrates has been reported to affect strawberry growth and disease suppression. This study investigated the impact of two substrate types, namely peat-reduced and peat-free substrates, on strawberry growth, health and disease suppression. Additionally, the effect of 10% v/v biochar addition to both substrate types was assessed on these parameters. A strawberry trial was performed in 2021 and 2022. Strawberry yield, aboveground fresh and dry weight, root rot severity caused by Phytophthora cactorum, lipid peroxidation, antioxidant capacity and the rhizosphere microbiome were evaluated. Results of the two trials varied partly due to differences in disease severity between years. Overall, the findings showed the potential of replacing peat with local alternatives, as no adverse effects were observed on the growth and health of strawberry plants grown on both substrate types. In 2022, the year with a high disease severity, an increase in root rot severity was found on strawberry plants grown on peat-free substrates compared with peat-reduced substrates, but this adverse effect was not observed in the blend with biochar addition. Results from both years indicate a neutral to positive effect of biochar on the aboveground fresh and dry weight and the stress levels of strawberry plants. The substrate type influenced the rhizosphere microbiome, whereas biochar addition only had little to no effect on the microbial community. This study shows potential for replacing peat in soilless strawberry cultivation with local alternatives, including biochar.