Phytotoxicity and hormesis in common mobile organic compounds in leachates of wood-derived biochars  

作　　者：Sean C.Thomas Ryan Ruan Nigel V.Gale Sossina Gezahegn 

机构地区：[1]Institute of Forestry and Conservation,John H Daniels Faculty of Architecture Landscape and Design,University of Toronto,33 Willcocks St.,Toronto,ON M5S 3B3,Canada.

出　　处：《Biochar》2024年第1期911-926,共16页生物炭(英文)

摘　　要：Although addition of pyrolyzed organic materials(biochars)to soil generally results in increased growth and physiological performance of plants,neutral and negative responses have also commonly been detected.Toxicity of organic compounds generated during pyrolysis,sorbed by biochars,and then released into the soil solution,has been implicated as a possible mechanism for such negative effects.Conversely,water-soluble biochar constituents have also been suggested to have“hormetic”effects(positive effects on plants at low concentrations);however,no specific compounds responsible have been identified.We investigated the relative phytotoxicity-and possible hormetic effects-of 14 organic compounds common in aqueous extracts of freshly produced lignocellulosic biochars,using seed germination bioassays.Of the compounds examined,volatile fatty acids(VFAs:acetic,propionic,butyric,valeric,caproic,and 2-ethylbutyric acids)and phenol,showed acute phytotoxicity,with germination-based ED50 values of 1-30 mmol L^(−1),and 2-ethylbutyric acid showed ED50 values of 0.1-1.0 mmol L^(−1).Other compounds(benzene,benzoic acid,butanone,methyl salicylate,toluene,and 2,4-di-tert-butylphenol)showed toxic effects only at high concentrations close to solubility limits.Although phytotoxic at high concentrations,valeric and caproic acid also showed detectable hormetic effects on seedlings,increasing radicle extension by 5-15%at concentrations of~0.01-0.1 mmol L^(−1).These data support the hypothesis that VFAs are the main agents responsible for phytotoxic effects of lignocellulosic biochar leachates,but that certain VFAs also have hormetic effects at low concentrations and may contribute to positive effects of biochar leachates on early plant development in some cases.

关 键 词：Acetic acid Caproic acid Charcoal Carboxylic acids GERMINATION Pyrogenic carbon Pyroligneous acid Valeric acid Volatile fatty acids Wood vinegar 

分 类 号：O62[理学—有机化学]