Germinação das sementes de Conyza canadensis e Conyza bonariensis em função da qualidade de luz

Abstract

RESUMO -Conyza canadensis e C. bonariensis são espécies invasoras cujo relato tem sido cada vez mais frequente, dada sua capacidade de desenvolvimento em áreas com palhada, sob sistema de semeadura direta (SSD). A luz é necessária para a germinação de diversas espécies de plantas daninhas, sendo considerado um fator de superação da dormência das sementes. A germinação de sementes sob SSD sofre o efeito da filtragem de comprimentos de onda pela palhada, que podem influenciar diretamente esse processo. O presente trabalho teve por objetivo estudar o efeito de diferentes filtros de luz sobre a germinação de sementes de C. canadensis e C. bonariensis. Foi realizado um experimento em que as sementes das espécies foram colocadas para germinar sobre papel mata-borrão umedecido com água, dentro de caixas gerbox transparentes envolvidas com filtros de luz azul, verde, vermelho, vermelho-distante, transparente e também em caixas de gerbox preta (ausência de luz). Foi avaliada a germinação aos cinco e 10 dias após a semeadura e no final desse período por mais 10 dias, com todos os tratamentos recebendo luz branca. As sementes de ambas as espécies sofrem significativamente o efeito da filtragem de comprimentos de onda, exceto o filtro vermelho, que proporcionou germinação superior à dos demais filtros, sendo inferior apenas ao transparente.Palavras-chave: buva, voadeira, filtro de luz, luz vermelha.ABSTRACT -The weed species Conyza canadensis and C. bonariensis have been increasingly reported, given their capacity to develop under the no-tillage system (NTS). Light is necessary for germination of several weeds, and is considered a factor of seed dormancy break. Seed germination in NTS is affected by light wave length filtering by straw, which can directly influence that process. The aim of this work was to determine the effect of different light filters on seed germination of C. canadensis and C. bonariensis. An experiment was carried out in which the seeds of these species were placed to germinate on blotting paper moistened with distilled water, inside transparent gerboxes involved with blue, green, red, light red and transparent light filters, as well as black gerboxes (light absence). Seed germination was evaluated at 5 and 10 days after sowing and at the end of this period for 10 more days, with all the treatments being under the condition of white light (filter absence). The seeds of both species were significantly affected by wave length filtering, except for the red filter which provided superior germination, inferior only to transparent filter.

Physiological potential of Physalis peruviana L. seeds under different temperatures and light wavelengths

“…According to Ozaslan et al (2016), the germination of Physalis angulata and Physalis philadelphica is slightly affected by photoperiods, which suggests that the seeds are slightly photoblastic, indicating that the same behavior occurs in P. peruviana. Light is commonly needed for germination in some species, as verified by Yamashita et al (2011) in a study with Conyza seeds, in which light was a determining factor for germination. In an experiment conducted by Silva et al (2016) with Jatropha curcas seeds, it was verified that in the presence of light, there is a homogenization of the germinative parameters in all batches analyzed, which does not happen in the dark.…”

Pre-germination Treatments, Quality of Light and Temperature on Syagrus coronata (Mart.) Becc. Seeds Germination

“…In the first experiment, the endocarps were removed with the aid of a hammer, before conditioning them to different qualities of light: white; red; far red; blue; and dark. For these conditions, trays with the seeds were covered with two sheets of transparent, red, overlaid red and blue, and blue cellophane paper, and aluminum foil, respectively (Yamashita et al, 2011). The treatments remained in the lab, exposed to natural light and at 25 °C.…”

Physiological characteristics of endive, lettuce and chicory seeds as a function of spectral quality

“…In contrast, for the 'Lisa Escarola' a similar performance was observed among all spectral qualities ( Figure 7D). interferes, as this pigment inhibits or stimulates germination according to the light spectrum received (Yamashita et al, 2011;Galindo et al, 2012).…”