Atividade alelopática de diferentes partes vegetais de Achillea millefolium L. e Cymbopogon citratus (DC) Stapf sobre a germinação de sementes e o desenvolvimento inicial de plântulas de Lactuca sativa L. e Cucumis sativus L.

Abstract

The objective of this work was to evaluate the allelopathic activity of different plant parts of Achillea millefolium L. and Cymbopogon citratus (DC) Stapf on the germination and initial development of seeds and seedlings of Lactuca sativa L. and Cucumis sativus L. (Achillea millefolium L.) and citrus (Cymbopogon citratus (DC) Stapf), bioassays were installed in the laboratory and in greenhouse. The treatments were aqueous extract of the different plant parts of A. millefolium L. and C. citratus L. at the concentrations of 0% (distilled water), 15%, 30%, 45%, 60% and 75%. Germination, first germination count, germination speed index, shoot length and primary root length, total dry mass of seedlings, seedling emergence, shoot length and primary root length, and total dry mass of emerged seedlings were evaluated. There was a negative allelopathic action of extracts of citrus grass and thousand-leaf flowers on germination and initial development of lettuce seedlings under laboratory conditions. There was a negative allelopathic effect on the first germination count, the germination speed index and the germination in lettuce seeds with the use of the 1000 leaf extract under laboratory conditions. The aqueous extracts of flowers, leaves and root of thousand leaves had toxic effect for the first count of the germination of cucumber seeds, and the speed index of the germination was more affected by the extracts of the flowers and leaves of thousand leaves, in conditions. There was allelopathic effect for shoot length and fresh mass of cucumber seedlings submitted to flower extracts and leaves of mille leaves under laboratory conditions. There was a significant allelopathic effect in the development of the root of the cucumber seeds submitted to extracts of leaves of thousand leaves, under laboratory conditions. The first count of germination, germination, seedling emergence, shoot length and root lettuce seedlings were not affected by wild-type root extract under protected environment conditions. The extracts of citrus grass negatively affected the emergence speed index, the fresh and dry mass of lettuce seedlings, under protected environment conditions. The extract of the thousand-leaf stem showed a detrimental effect on the root length of lettuce seedlings under protected environment conditions. Milk leaf extract negatively affected the root length of lettuce seedlings at 15, 30 and 45% concentrations and the dry mass at all concentrations tested under protected environment conditions.