ObjectivesAs a kind of soil amendment, biochar has been proved effective to improve soil fertility and increase crop yield. The responses of crop growth to biochar amendment result from changes in the interaction of soil and plant on plant development, which finally influences crop productivity. Therefore, it is helpful to understand the mechanism of plant response to biochar amendment if we shift our view from biomass production to plant phenotype and gene expression. This will also provide a sound theoretical base for biochar usage in agriculture.

Major advancesIn this review, we summarized the progress that researchers have got about biochar effects on plant growth from the following aspects: crop productivity, root growth and morphology, plant resistance to diseases and pests, and plant phenotype and gene expression. The mechanisms of biochar amendment on plant phenotype and gene expression were also discussed. In conclusion, studies that invested the effects of biochar on plant phenotype and gene expression are not enough.

Suggestions and expectationsFurther studies should pay much attention to holding a systemic view on biochar studies, including establishing standard rules and setting up databases for biochar properties, effects and so on.