İngilizce Soru Bankası - Paragraf soruları Soru 147

147-) According to the passage, allelopathic plants —.

The American chestnut was once the most common canopy tree in the deciduous (non-evergreen) forests of the eastern United States. It shaded areas from New England to Georgia until the fungus Cryphonectria parasitica wiped out the species in the terrible forest disaster of the early 20th century. The fungus continues to kill chestnuts before they can mature. The vacuum left by the chestnut's destruction is now filled with other species. Considerable research has gone into understanding what happened to the American chestnut. But some scientists remain interested in getting to the root not of its destruction, but rather of the centuries of dominance enjoyed by the massive, fragrant and economically important tree. A team of scientists recently put forward the idea that the American chestnut may have been engaged in the chemically charged competition known as allelopathy. An allelopathic plant releases potentially toxic substances into the environment through its roots, its leaves or processes such as evaporation. Black walnut, sycamore and sassafras trees are just a few known allelopaths that limit the germination of competitor. It's likely that the list will soon branch out to include chestnut.