Something old, something new in allelopathy review: what grassland ecosystems tell us

Allelopathy may be a relevant phenomenon in the dynamics of grasslands, a biome that presents high biodiversity and provides unique ecosystem services. Research on allelopathy in grasslands has been conducted worldwide and important suggestions to improve studies have been made in the recent past. However, few general patterns have been established so far. In this review, we report and discuss allelopathy research conducted in grassland ecosystems. We carried out a systematic search for allelopathy studies in grasslands and assessed descriptive, methodological and conceptual aspects of each article. We also evaluated if research quality has improved in recent years. We found that the studies investigated interactions mostly involving herbaceous species in many types of grasslands around the world. The studies have assessed the potential of allelopathy in structuring natural grasslands and artificial pastures and of applying allelopathy to bioherbicide development and to restoration of natural ecosystems. We observed inconsistency in terminology and discussed allelopathy definition. Moreover, we found that in recent years, allelopathy research has improved in some experimental design issues, but not in others. This shows that not all recommendations in literature have been taken into account. Otherwise, innovative methods and analytical tools have emerged. In spite of slow progress, allelopathy has shown potential relevance in dynamics and restoration of grasslands, as well as in weed management in cultivated systems. Thus, a better knowledge about allelopathy can lead to advances in science and in applied fields.