Time Responses and the Susceptibility of Roadside Plants to Growth Regulation

摘要

Time responses, particularly daily oscillations, of seven species of plants were studied. Five of the species were weeds: Ambrosia artemisiifolia L., common ragweed; Ambrosia trifida L., giant ragweed; Cirsium arvense (L.) Scop., Canada thistle; Euphorbia esula L., leafy spurge; and Taraxacum officiale Weber, common dandelion. Two were desirable as roadside ground cover: Medicago sativa L., alfalfa, and Triofolium pratense L., red clover. Methods were developed for germinating weed seeds, a process which is often difficult to accomplish in a laboratory. Variations in plant populations and the lack of good statistical evidence were important factors in not being able to designate any one time of day to be consistently better for controlling weeds by 2, 4-dichlorophenoxyacetic acid (2,4-D) under controlled environmental conditions.