Reduction of tobacco alkaloid bioaccumulation in pea shoots: a comparative study of biochar derived from cow dung and maize straw.

Tobacco alkaloids in tobacco-cultivated soils pose potential risks for succeeding crops, due to their allelopathy and toxicity. Effects of biochar on the dissipation of tobacco alkaloids in soil-crop systems remain poorly understood. In this study, a 40-day pot experiment was conducted to explore the effect of cow dung biochar (CDBC) and maize straw biochar (MSBC) on the uptake of nicotine and nornicotine by pea (Pisum sativum L.) and their dissipation in an agricultural soil. The results revealed that the bioaccumulation of nicotine and nornicotine by pea shoots in the soils added with CDBC and MSBC at 1.5% and 3.0% significantly decreased by 46.97-79.13% and 33.64-71.59%, respectively. CDBC more effectively decreased the uptake and bioaccumulation of nicotine and nornicotine by pea shoots than MSBC due to the higher soil pH and nutrient content. In addition, the enhanced relative abundances of soil nicotine-degrading bacteria belonging to the genera Arthrobacter and Gemmatimonas also contributed to the decreasing uptake of nicotine by pea plants. The decreased bioavailability in the soils due to the increased adsorption was the key factor for the reduced bioaccumulation of tobacco alkaloids. This study provides guidance to protect subsequent crops in tobacco-cultivated soil from tobacco alkaloids with biochar.