Autotoxicity

Autotoxicity is a phenomenon in which chemicals released by a plant or other organism inhibit the growth or germination of conspecific individuals—plants of the same species or closely related taxa. It is a subset of allelopathy and is most widely studied in crops and forest ecosystems where repeated planting or residue buildup can affect regeneration.

In plants, autotoxic compounds are often phenolics, terpenoids, alkaloids, or organic acids released via root exudation, litter decomposition, or volatilization. They may accumulate in the rhizosphere or soil organic matter, and their effects depend on concentration, soil pH, texture, moisture, and microbial activity, which can modify persistence and toxicity.

Autotoxic effects typically include reduced seed germination, delayed or stunted seedling growth, abnormal root morphology, and lowered biomass or yield in subsequent crops of the same species. The phenomenon can contribute to replant disease and can influence succession and community composition in natural ecosystems.

Reported cases include autotoxic effects in lettuce, tomato, alfalfa, and strawberry crops, as well as in some tree species where past plantings suppress regeneration of the same species. The practical importance is greatest in systems with continuous monoculture or intensive residue retention.

Management strategies focus on disrupting toxin accumulation and accelerating degradation, such as crop rotation with non-host species, tillage or soil solarization, organic matter amendments to boost microbial breakdown, and residue management. Breeding for reduced exudation or tolerance, and proper irrigation and drainage, can also help mitigate autotoxicity.