Abstract
This study aims to evaluate the phytotoxicity potential of leaf and root extracts of Drimys brasiliensis on the germination and seedling growth of Panicum maximum and Euphorbia heterophylla and its influence on metaxylem cell size in the seedling roots of the latter specie. The leaf and root extracts were fractionated by partition chromatography, and the hexane and ethyl acetate fractions obtained from each organ were evaluated at different concentrations for phytotoxic activity in several bioassays. In seedling growth tests, we compared the effects of these fractions with the herbicide oxyfluorfen. The hexane fraction of the root extracts showed a higher inhibitory potential on the germination and growth of weeds and reduced the average size of the metaxylem cells of E. heterophylla roots by more than 50% . The inhibitory effects of the root hexane fraction on seedling growth was similar to the herbicide, indicating that D. brasiliensis is a possible alternative form of control for the weed species examined.
Highlights
Plants are capable of producing secondary metabolites that affect the germination and growth of other plants; this interaction has been defined as allelopathy (INDERJIT et al, 2011; WEIR et al, 2004)
The aim of this study is to evaluate the phytotoxic effects of fractionated crude extracts of D. brasiliensis roots and leaves on the germination and early growth of E. heterophylla and P. maximum, as well as its influence on the metaxylem cell size of E. heterophylla roots
The AcOEt fraction promoted a linear decrease in germination and synchrony (17% and 0.157 for each additional 0.01 mg mL-1 of solution applied, respectively), and mean germination time increased in a linear manner (1.57 days for each additional 0.01 mg mL-1 of solution applied)
Summary
Plants are capable of producing secondary metabolites that affect the germination and growth of other plants; this interaction has been defined as allelopathy (INDERJIT et al, 2011; WEIR et al, 2004). Allelopathic relationships may occur in a positive or negative manner through the production of chemical compounds known as allelochemicals. Allelochemicals are released into the environment by different mechanisms, such as volatilization, leaf leaching or root exudation (WEIR et al, 2004). The leaves and roots constitute the main source of allelochemicals (WU et al, 2009); due to the specific production of metabolites that are directly exuded into the environment, many compounds with relevant biological activities have. Weeds are adaptable to different habitats and often compete with crops by taking advantage of the favorable conditions that occur in agricultural systems. Secondary metabolites derived from plants may serve as a promising environmentally friendly tool for weed management.
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