Germination of Leonotis nepetaefolia seeds as a function of maturity stadium and globe position in the plant

摘要

Leonotis nepetaefolia is a common weed in no-tillage corn crop systems, yielding a great number of seeds during winter. The present work aimed to evaluate the germination of this species'seeds originated from glomerules obtained at different maturity stages and positions in the plant, as well as their quality after 15 month - storage.Three assays were conducted in the laboratory, to evaluate germination rate and germination speed index; the first and the second experiments were carried out immediately after seed harvest, and the third one, 15 months later. The dormancy breakup treatment was tested only in the first assay. Immediately after harvest, highest germination was obtained from dry glomerule seeds on the side position. Fifteen months after seed harvest, the glomerules on the side and top presented the greatest germination percentages, without any differences occurring between the maturity stages. Storage increased seed germination. The dormancy break up methodology submitting Leonurus cardiaca seeds to pre-cooling at temperatures ranging from 7 to 10 ?oC, for 7 days, at absence of light, was not adequate for this species.