2019 ASHS Annual Conference

Biochar (BC) is the byproduct of pyrolysis of biomass. Previous studies showed that the biochar has potential to be used in container substrate at high incorporation rates. It can be beneficial to plants productivity both directly due to its nutrient content and release characteristics and indirectly by improving retention of nutrients. Mycorrhizae (MC) can increase the growth of plants and their nutrition uptake. The objective of this study was to investigate the effects of biochar, mycorrhizae, and fertigation on tomato and pepper plants in container. The container mixes used in this study were formulated by mixing 50%, 70% and 90% pine bark biochar (PBC) with 5% vermicompost (VC) with the rest being commercial substrates, and a commercial substrate was used as control. Tomato and pepper plants were transplanted into one of the treatments on August 8th, 2017 and granular commercial mycorrhizae containing both Endo- and Ecto-mycorrhiza were added to half the containers during transplanting and plants were fertigated with 200 or 300 mg L^-1 N. Plant growth index (GI) and leave greenness (SPAD) were measured biweekly and at the end of the experiment, shoot dry weight (SDW) were measure. Since no mycorrhizal fungi was found associated with the roots, the treatments with or without mycorrhizae were combined. Biochar and fertigation had no interactions on SPAD, SDW or GI of tomato or pepper plants. For pepper plants, those grown in 90% biochar had significantly lower SPAD, GI and SDW than the others while those grown in 50% biochar and 70% biochar had similar GI and SDW to the control (the commercial substrate). For tomato plants, those grown in commercial substrate had greater SPAD than the others while those grown in 90% biochar had lower SPAD and lower SDW compared to the others. Tomato plants in 50%, 70% or 90% biochar had higher or similar GI compared to control and those in 50%, 70% biochar had higher SDW in comparison to control. No differences were observed for either tomato or pepper plants grown in substrates with or without vermicompost. The biochar used in this experiment could potential replace commercial substrate as container substrate and vermicompost did not provide additional benefits on plant growth.