Seasonality effect on the allelopathy of cerrado species

Abstract

The Brazilian cerrado presents strong climate seasonality. During the dry season, plants may be exposed to stressful situations, such as a soil surface water deficit, that stimulate their chemical defenses. However, the seasonality effect on the production of allelopathic compounds of cerrado plant species is poorly understood. In this study, the phytotoxic activities of common native cerrado plants were evaluated during rainy and dry seasons. Crude leaves extracts (10% concentration: weight/volume, with dry leaves and distilled water) from eleven species were tested on lettuce and sesame germination. The negative effects on germination percentages, rates and informational entropies of the target species were higher when submitted to plant extracts from the dry season, where the germination rate was the most sensible parameter. The higher sensibility of lettuce and the germination rate parameter showed this difference. Only two exceptions had higher effects for rainy season extracts; one species showed higher negative effects on germination informational entropy of lettuce and another species on the germination rate of sesame. Thus, increases in the allelopathic activity were seen in the majority of the studied cerrado plant species during the dry season. These distinct responses to stressful situations in a complex environment such as the Brazilian cerrado may support the establishment and survival of some species.Keywords: chemical ecology, phytotoxicity, secondary metabolites. Efeito da sazonalidade sobre a alelopatia de espécies de cerradoResumo O cerrado brasileiro apresenta forte sazonalidade climática. Durante a estação seca as plantas podem estar expostas a situações estressantes, tais como um déficit de umidade nas camadas superficiais do solo, que estimulam suas defesas químicas. No entanto, o efeito da sazonalidade na produção de compostos alelopáticos de espécies vegetais de cerrado é pouco conhecido. Neste estudo, as atividades fitotóxicas de plantas nativas comuns de cerrado foram avaliadas durante as estações chuvosa e seca. Extratos brutos de folhas (concentração 10%: peso/volume, com folhas secas e água destilada) de onze espécies foram testados sobre a germinação de alface e gergelim. Os efeitos negativos sobre as porcentagens de germinação, velocidades e entropias informacionais das espécies-alvo foram maiores quando submetidas a extratos vegetais da estação seca. A maior sensibilidade da alface e do parâmetro velocidade de germinação mostraram essa diferença. Apenas duas exceções tiveram maiores efeitos para extratos da estação chuvosa; uma espécie mostrou maiores efeitos negativos sobre a entropia informacional de germinação de alface e outra espécie sobre a velocidade de germinação de gergelim. Assim, aumentos na atividade alelopática foram vistos na maioria das espécies vegetais do cerrado estudadas durante a estação seca. Estas respostas distintas a situações estressantes em um ambiente complexo como o cerrado brasileiro podem auxiliar no estabelecimento e na sobrevivência de algu...

Seasonal variation in allelopathic potential of the leaves of Copaifera langsdorffii Desf.

“…us, seasonal changes in the water status of Cerrado can be critical to signaling changes in allelochemical synthesis, maximizing the action of allelochemicals on targets. Corroborating our observations, Gatti et al (2014) showed that Cerrado plant species presented the greatest phytotoxic potential with extracts obtained from specimens collected during the dry season. Pinto & Kolb (2016) observed that using extracts from ve Cerrado species obtained from specimens collected after the dry season or during the wet season presented greater phytotoxic e ects, and Murakami et al (2009) showed that extracts from leaf samples did not show variation in allelopathic potential between any of the four seasons.…”

Biological properties of disturbed and undisturbed Cerrado sensu stricto from Northeast Brazil

“…The ecosystem is the second largest Brazilian domain after the Amazonian (Gatti et al, 2014) and extends over all regions of Brazil.…”

N deposition affects allelopathic potential of Amaranthus retroflexus with different distribution regions

“…The reason could be a result of the contained higher concentration of secondary metabolites for the leaves of plants that growths in high latitudes compare with that growth in low latitudes (Wright et al 2004). Gatti et al (2014) also found that climate conditions can affect plant secondary metabolism (such as precipitation and temperature) and then alter the allelopathic activity of plant species via alter the production of allelochemicals. The result may also be attributed in part to the fact that A. retroflexus originated in America (Mandák et al 2011, Yang et al 2011) and/ or south-eastern Asia (Yang et al 2011) which have higher similarity climate conditions as Zhenjiang rather than Jinan.…”