Alelopatia de milheto e crotalária na germinação de sementes de alface

Abstract

Seed germination is an essential process for establishing lettuce growing areas. The use of cover crops can bring several benefits in crop production systems, however, some species can produce allelopathic compounds, and cause negative effects for cultivated species. Thus, the objective of this work was to evaluate the allelopathic effects of extracts produced with different parts of Crotalaria and Millet (separately) and at different concentrations, on the germination and growth of lettuce seedlings. The research was carried out in the laboratory. Lettuce seeds of the cultivar “Lisa” were used. The design adopted in each experiment was completely randomized (DIC), with a 3x4 factorial scheme (plant parts x extract concentrations), with 4 replications. To elaborate the extracts of millet and sunn hemp, parts of the plants were used: roots, leaves and inflorescences, separately. The concentrations used were: 0, 25, 50 and 100%. The variables analyzed were: germination, germination speed index, length of roots and shoots, and dry mass of roots and shoots. The results were submitted to analysis of variance, comparison of means, by the tukey test, and regression analysis. It was possible to conclude that the extract of crotalaria plants interferes with the germination of lettuce seeds. Leaves and inflorescence extracts have greater negative interference on lettuce germination, compared to root extracts, however, there are few effects on seedling growth. Extracts from crotalaria plants, at a concentration of 100%, reduce the germination and growth of lettuce seedlings, regardless of the part of the plant used to prepare the extract. The extract of millet plants interferes with the germination of lettuce seeds. The extract prepared with leaves has a greater allelopathic effect, compared to the root extract, on seed germination, however, with little interference in seedling growth. The concentration of extracts, regardless of the part of the plant used, reduces seed germination and seedling growth, with greater effects at the 100% concentration.