in order to study the cardinal temperatures of three weeds henbane (hyoscyamus niger l), aconite (aconitum napellusl l.) and hemp (cannabis sativa l.) at seven levels of temperatures (5, 10, 15, 20, 25, 30 and 35 °c), an experiment was carried out in completely randomized design with 3 replications and factorial experimental arrangement in weeds research laboratory, faculty of agriculture, ferd...