植物的根、茎、叶一生中不断地向周围环境分泌气态或液态的分泌物。有些分泌物对其它植物有刺激生长的作用,也有些分泌物对其它植物有抑制生长的作用,还有的分泌物能抑制其它植物的病虫害。农学家们利用各种分泌物的不同作用,在间、混、套种时正确地选择作物,使两种作物的分泌物互相促进,从而使 The roots, stems and leaves of plants continuously release gaseous or liquid secretions to the surroundings during their lifetime. Some secretions on other plants stimulate the growth of the role, but also some secretions on the growth inhibition of other plants, as well as secretions can inhibit other plant pests and diseases. Agronomists use the different effects of various secretions to properly select crops during intercropping, intercropping, and mutual excretion of the two crops so that