Allelopathic research in Brazil

Abstract

In this article, we review allelopathy studies conducted in Brazil or involving plant species that occur in the country. Conceptions and misconceptions associated with allelopathy, as well as some international criteria to be applied in allelopathic research, are presented and discussed. We observed a sharp increase in the number of papers on this subject conducted in Brazil between 1991 and 2010. However, most studies are conducted under laboratory conditions, lack a clear hypothesis or a solid justification, and typically make use of target species that do not co-exist with the donor species under natural conditions. We also found that most studies do not take the additional steps in order to purify and identify the bioactive molecules. We recommend that further studies be conducted in order to explore the potential of plant biodiversity in Brazil. Such studies could lead to the development of new molecular structures (allelochemicals) that could be used in the control of pests and weeds, thereby reducing the use of the harmful synthetic herbicides that are currently being widely employed.

Pequi leaves incorporated into the soil reduce the initial growth of cultivated, invasive and native species

“…Highly concentrated extracts, or exaggerated quantities of plant tissue used in the experiments, may lead to toxic effects due to the extreme concentration; however, they do not reflect concentration levels which bioactive substances would reach in the environment surrounding the allelopathic species (Blum 2011, Reigosa et al 2013.…”

“…The preparation of aqueous extracts obtained from different plant tissues, the use of filter paper as a substrate, and the selection of cultivated or invasive species as target, have however, been the most common procedure (Gatti et al 2004, Oliveira et al 2004, Aires et al 2005, Pina et al 2009, Reigosa et al 2013. Less common is the use of crushed leaves added to the soil (Souza et al 2007, Pina et al 2009).…”

“…Less common is the use of crushed leaves added to the soil (Souza et al 2007, Pina et al 2009). In most studies conducted in Brazil, the concentration rate of the extracts has generally been below 5% in proportions between weight/weight, weight/volume or volume/volume (Reigosa et al 2013).…”

“…However, the scientific basis that underlie these two studies differ: first, phytotoxic studies investigate chemical properties and interactions among species that do not necessarily coexist in their regions of origin; second, they normally employ extracts prepared with organic solvents and methodologies which optimize the extraction of the active compounds; finally, they frequently utilize filter paper or other types of inert substrates (Blum 2011, Reigosa et al 2013. Allelopathy, on the other hand, is the science that studies chemical interactions among plants in their natural environments.…”

“…Allelopathy, on the other hand, is the science that studies chemical interactions among plants in their natural environments. Therefore, studies conducted under controlled conditions which attempt to contribute to the deciphering of allelopathic interactions should meet certain minimum criteria: they should employ species that coexist in their natural environments, use water in the preparation of extracts, utilize substrate representative of the location where the phenomena takes place, and be guided by questions and hypotheses which have ecological relevance to the species, population or community (Inderjit et al 2001, Inderjit 2005, Blum 2011, Reigosa et al 2013…”