Phytotoxic potential of Senna occidentalis and Senna obtusifolia

Abstract

ABSTRACT. This work aimed to investigate the phytotoxic potential of the aerial and underground parts of Senna occidentalis and S. obtusifolia on the germination and initial growth of lettuce and onion. Four concentrations were used of each ethanol extract (0, 250, 500 and 1000 mg L -1 ), with four replications of 50 seeds. From the investigated species, the aerial part of S. occidentalis interfered in onion germination and the aerial part of S. obtusifolia interfered in the germinations of lettuce and onion. The ethanol extract from the aerial and underground parts of the studied species inhibited the root growth of lettuce and onion. The hypocotyl/coleoptile growth in lettuce and onion was inhibited by the extract of S. obtusifolia aerial part and the underground part of S. occidentalis and S. obtusifolia. The results obtained make it possible to infer that the studied species contain substances that influence the germination and growth of the target seedlings.Key words: ethanol extract, leguminosae, weeds. RESUMO. Potencial fitotóxico de Senna occidentalis e Senna obtusifolia. O objetivo do presente trabalho foi investigar o potencial fitotóxico das partes aérea e subterrânea deSenna occidentalis e S. obtusifolia sobre a germinação e o crescimento inicial de alface e cebola. Utilizaram-se quatro concentrações de cada extrato etanólico (0, 250, 500 e 1000 mg L -1 ), com quatro repetições de 50 sementes. Das espécies investigadas, a parte aérea de S. occidentalis interferiu na germinação de cebola e a parte aérea de S. obtusifolia, na germinação de alface e cebola. O extrato etanólico da parte aérea e subterrânea, das espécies em estudo, inibiu o crescimento da raiz de alface e de cebola. O crescimento do hipocótilo/coleóptilo de alface e cebola foi inibido pelo extrato da parte aérea de S. obtusifolia e da subterrânea de S. occidentalis e S. obtusifolia. Os resultados obtidos permitem inferir que as espécies em estudo contêm substâncias que influenciam a germinação e o crescimento das plântulas-alvo.Palavras-chave: extrato etanólico, leguminosae, plantas daninhas.

Assessment of Allelopathic Potential of Senna garrettiana Leaves and Identification of Potent Phytotoxic Substances

“…Allopathic activity has been reported in a large number of Senna species. For example, an extract of the aerial parts of Senna obtusifolia (L.) Irwin & Barneby inhibited the seed germination and growth of Lactuca sativa L. and Allium cepa L. [7]. An extract of S. occidentalis reduced the growth of Handroanthus chrysotrichus (Mart.…”

“…The genus Senna (Fabaceae family) includes approximately 300 species with a tropical distribution, most of which are widely found in the Americas, Africa, Australia, and Asia [17]. This genus contains annuals, subshrubs, and woody and erect plants [7]. The pharmacologically bioactive compounds in various Senna spp.…”

“…have been shown to possess antimalarial, antidiabetic, antimicrobial, antioxidant, anti-inflammatory, analgesic, antitumor, antinociceptive, and anticancer properties [19]. Notably, several members of this genus also have allelopathic potential and contain potent phytotoxic substances [7,20].…”

<b>Allelopathic bioactivity of fresh and infused aqueous extracts of Brazilian cherry (<i>Eugenia uniflora</i> L.) on lettuce and maize

“…Average germination rate and root length of lettuce seeds for each concentration of fresh and infused aqueous extracts (A and C, respectively) compared by Tukey's test with a significance level of 5%, and all treatment groups compared by Dunnet's test with the control (B and D, respectively) with a significance level of 5% of significance according to extract (fresh -Fr and infused -In). Peres et al (2010) discuss that stimulatory or inhibitory effects may be caused by different concentrations. Fluctuation between stimulatory and inhibitory responses, depending on the extraction methods and the extract concentration, has also been observed by Pelegrini and Cruz-Silva (2012) in Coleus barbatus (A.)…”

“…The effects observed in target plants result from the biological activity of the extract, and this activity varies depending on its method of preparation and concentration of allelochemicals (Faria, Gomes Júnior, Sá, & Cassiolato, 2009;Peres, Cândido, Bonilla, Faccenda, & Hess, 2010;Correa, Marco Junior, & Costa Junior, 2013). The mode of action of allelochemicals is related to its concentration.…”