Biochar enhances yield and quality of tomato under reduced irrigation

• Biochar effects on yield and quality of tomato were studied under different irrigations.
• Biochar enhanced soil water storage under reduced irrigation (DI and PRD).
• PRD, in combination with biochar produced almost same yield as FI.
• PRD, in combination with biochar may be used to enhance crop water use efficiency.

Biochar is an amendment that can be used for enhancing soil water storage which may increase crop productivity. The objective of this study was to investigate the effects of biochar on physiology, yield and quality of tomato under different irrigation regimes. From early flowering to fruit maturity stages, the plants were subjected to full irrigation (FI), deficit irrigation (DI) and partial root-zone drying irrigation (PRD) and two levels of biochar (0% and 5% by weight). In FI, the plants were irrigated daily to pot water holding capacity while in DI and PRD, 70% of FI was irrigated on either the whole or one side of the pots, respectively. In PRD, irrigation was switched between sides when the soil water content of the dry side decreased to 15%. The results showed that addition of biochar increased the soil moisture contents in DI and PRD, which consequently improved physiology, yield, and quality of tomato as compared with the non-biochar control. However, leaf N content and chlorophyll content index (CCI) were decreased significantly in biochar treated plants. Furthermore, given a same irrigation volume, PRD offered advantages over DI in improving water use efficiency, leaf relative water content, membrane stability index and fruit yield. Overall, fruit quality was improved under reduced irrigation (i.e. DI and PRD) as compared with FI. It was concluded that incorporation of biochar under DI and particularly, PRD might be a novel approach to improve water productivity and quality of tomato.