Desenvolvimento de novos bio-herbicidas para o controle sustentável de plantas invasoras do gênero Amaranthus

Abstract

The objective of this work is to evaluate extracts from the plants H. brevipes, H. crenata, H. campestris, H. saxatilis and H. suaveolens as bioherbicides that inhibit the photosynthesis of weeds of the genus Amaranthus. Firstly, these extracts were evaluated as inhibitors of photosystem II (PSII) by measuring chlorophyll a (Chl α) fluorescence. In this study, the H. brevipes extract showed the best results, reducing performance indices (PI abs, PICsm and PICSo) by 63, 58 and 65%, respectively. Furthermore, the decrease in the phenomenological parameters ABS/CSm, TRo/CSm, ETo/CSm and RC/CSm of PSII indicate that the low energy absorption reduced transport of electrons. By blocking the transport of electrons in these sections, all the energy that would have been spent in the process was dissipated in the form of heat, interrupting the plant's development. H. brevipes extract has selective action as a post-emergence herbicide. Since this extract acts independently of concentration on the A. hybridus species and in high concentration doses on the A. Spinosus species. According to multivariate statistical analysis, the majority of metabolites correlated with activity were from the class of terpenoids, flavonoids and phenylpropanoids. These results suggest metabolites with promising bioherbicidal action in the H. brevipes extract. Thus, phytotoxic behaviors based on plant extracts can serve as a valuable tool in the development of a bioherbicide, since natural products represent an interesting alternative to replace commercial herbicides.