Updated: Dec 27, 2019
According to Marie Iannotti, an experienced gardener and former editor of the Mid-Hudson Gardner's Guide, allelopathy is the prevention of growth in one species of plants by chemicals produced by another species. This prevention causes the death of the weaker plant.
The chemicals released by different parts of the plant or can be set free through natural decomposition. In a study from Professor James J. Ferguson and Bala Rathinasabapathi, from Florida University, it was reported that the effects of allelopathy usually include reduced seed germination and seedling growth.
On Eco Sensorium.org there is an article written by a well-known environmentalist, that Allelopathy may be beneficial to some plants because they receive more natural nutrients water and sunlight from their environment without having to release any chemicals that may harm surrounding plants.
Rapidly evaporating chemicals can cause direct or indirect harmful or beneficial on plants in the same zones. General Biology, Allelopathy is the chemical compounds that escape into the environment and may produce toxic or beneficial effects of one plant on another.