Development of a pyrolytic aqueous phase derived from resinous wood and having a biostimulant action for plant growth

Wood vinegar (WV) is a by-product of biomass pyrolysis, which is a thermochemical conversion process of lignocellulosics in absence of oxygen. A growing interest for WV has developed in the past decade for its biostimulant and biopesticide potential. The objective of this study was to investigate the biostimulant potential on five different plant species (tomato, lettuce, basil, pepper and carrot), and the antimicrobial activity of two WVs produced from local Canadian black spruce residues (black spruce wood vinegar (BSWV) and black spruce barks vinegar (BSBV)). For tomatoes and carrots, two treatments of BSWV diluted 500-fold and 800-fold with 50% (F50%) of the fertilizer recommended rate (RR) were applied by foliar spraying. For lettuce, basil and pepper, 12 treatments of BSWV and BSBV diluted 300-, 650- and 1000-fold with F50% were applied by foliar spraying or root application. For all the plant species, treatments with tap water using 50% (F50%) or 100% (F100%) of the RR were used as controls. Our results showed that both WVs enhanced the growth and yield of lettuce, basil and pepper, but had no effect on tomatoes and had a limited effect on carrots. Foliar application of WV was better than root application, and random effects on growth and yield of WV concentrations were observed. Antifungal and antibacterial activities were evaluated against two potatoes pathogenic fungi and three potatoes pathogenic bacterial strains, respectively. Both WVs exhibited 100% inhibition against the two fungi at 3.5% (v/v) and against the three bacteria at a concentration ranging between 0.8 and 2% (v/v). Understanding the effects of WV and the best conditions and practices for their application is an important step toward sustainable agriculture and environmental protection.