Considering the potential ecological risks and food safety issues of tobacco alkaloid accumulation, this study builds upon the noted bitterness in the edible parts of the peas (Pisum sativum L.) after their growth following continuous tobacco cropping. Based on previous study using peas as the research object, the field-measured values of six tobacco alkaloids with obvious soil accumulation trends were used to evaluate the allelopathic effects of various tobacco alkaloids. Tobacco alkaloids with the strongest allelopathic effects were selected as representative substances to study how they affected the growth, metabolism, and edible value of pea plants. Notably, mysomine had the strongest synthetical allelopathic index (SE). Myosmine was absorbed by pea plants primarily through the roots and subsequently translocated, accumulating in organs in the order of leaves > roots > stems. This organ-specific distribution led to pronounced bitterness concentrated mainly in the leaves. The accumulation of tobacco alkaloids reduced the content of photosynthetic pigments (chlorophyll and carotenoids) in the pea leaves and caused oxidative damage to the cell membranes (MDA, GSH, Pro, POD, SOD increased significantly.), reducing the content of sugar substances (such as sucrose and D-frutose) in the leaves. Under the stress of tobacco alkaloids, the hormone (IAA, JA, SA) content of the pea plants increased, which stimulated the synthesis of flavonoids, terpenoids, and amino acids. This increased the source of bitter substances in the leaves, changing the structure of leaf nutrients and further aggravating the bitterness. This study systematically elucidates the physiological effects of tobacco alkaloids on pea seed germination, seedling growth, plant metabolism, and quality formation, reveals the potential risks of their residues to subsequent crop production and food safety, and thereby provides a theoretical basis for scientifically evaluating the allelopathic effects of alkaloids and optimizing cropping systems.
Yuan et al. (Sat,) studied this question.