Does competition stress decrease allelopathic potential?

Abstract

a b s t r a c tIn natural communities, plants compete in different ways, among them chemical interactions in the form of allelopathy. Whereas the effects of abiotic stresses (temperature, light, nutrients, etc.) on the production of allelochemicals are well known, only few studies deal with the impact of the stress induced by competition. When they do so, these studies are done under experimental conditions. The aim of this study is to evaluate the effect of intra-specific competition on the production of allelochemicals and biomass of Pinus halepensis Mill. in a natural forest using three levels of density. Phenolics and aliphatic acids were extracted from pine needles, analysed and quantified by GC-MS. Trunks, branches, needles and necromass were measured. We observed an increase in allelochemical content at low or medium level of competition and a decrease at high competition level. Moreover trees in competition allocate proportionally more biomass to the trunk and less to foliage and branches. This study provides evidence of substantial changes in allocation between the primary and the secondary metabolism.

Interactions between Sonchus oleraceus L. and some weeds in agroecosystems in Egypt

“…(Rivoal et al, 2011). Thus, interference of the donor species may be ineffective under high density of the targets.…”

Interferência entre plantas daninhas e a cultura: alterações no metabolismo secundário

“…Pouco se sabe sobre o impacto do estresse ocasionado pela interferência entre plantas no metabolismo secundário (Rivoal et al, 2011;Silva et al, 2014). Entretanto, são conhecidos os efeitos de estresses abióticos sobre a produção de metabólitos secundários.…”

“…Normalmente, os parâmetros utilizados para mensurar os efeitos da competição são variáveis morfológicas contudo, poucos são os trabalhos relacionados aos estresses fisiológicos e ao metabolismo secundário das plantas envolvidas na competição (Silva et al, 2014). Atualmente é possível afirmar que há a ativação de mecanismos de defesa quando ocorre competição (Broz et al, 2010;Rivoal et al, 2011;Silva et al, 2014;Gal et al, 2015;Agostinetto et al, 2016).…”

“…Altas densidades de Pinus halepensis Mill., diminuíram a concentração total de metabólitos secundários, reflexo do crescimento da planta que tende a favorecê-lo em altura, a fim de receber mais luz e de qualidade, induzindo a modificação no metabolismo (Rivoal et al, 2011). Já a competição de arroz cultivado com arroz-vermelho indicou que a planta daninha obteve maior suporte para competir com a cultura, por ter desencadeado o metabolismo secundário com maior produção de compostos fenólicos (Langaro et al, 2011).…”

Allelopathy: driving mechanisms governing its activity in agriculture

“…Similarly, the environmental stresses arising from the interaction among plants are also important for the production of other allelochemicals (Rivoal et al 2011). For example, rice seedlings cultivated with Echinochloa crus-galli L. Beauv.…”