Compostos fenólicos de fruteiras nativas: caracterização e potencial para desenvolvimento de bioherbicidas pré-emergentes

Abstract

The growing resistance of weeds to synthetic herbicides, combined with the environmental impacts associated with their use, has driven the search for sustainable alternatives, such as the use of phenolic compounds from native fruit trees with bioherbicidal potential. In this context, this study aimed to evaluate the allelopathic potential of leaf extracts from fruit trees and relate their effects to the presence of bioactive phenolic compounds. The experiment was carried out at the Plant Physiology Laboratory of the Federal University of Technology – Paraná (UTFPR), Dois Vizinhos Campus. A completely randomized experimental design was used in a 20 × 3 factorial scheme (fruit tree extract × extraction technique), with four replicates of 100 seeds per experimental unit. Leaves from P. cauliflora, P. peruviana, Inga spp., Eugenia uniflora, Psidium cattleianum var. Lucidum), P. cattleianum var. Sabine, Campomanesia xanthocarpa, Myrcianthes pungens, Eugenia pyriformis, Campomanesia guazumifolia, Casearia sylvestris, Myrciaria glazioviana, Eugenia involucrata, Garcinia brasiliensis, Randia ferox, Allophylus edulis, Eugenia myrcianthes and Syzygium jambolanum were used. The extraction techniques employed were maceration, infusion, and hydroalcoholic extraction. Germination (%), germination speed index (GSI), and mean germination time (MGT) were evaluated in lettuce, corn, and soybean seeds, as well as in invasive species such as Sida rhombifolia, Urochloa brizantha, Bidens pilosa, and Lolium multiflorum. Characterization of phenolic compounds was also performed using high-performance liquid chromatography (HPLC). Hydroalcoholic extraction proved to be the most efficient method, promoting greater suppression of germination and, in some cases, total inhibition, particularly in lettuce and soybean. Among the species evaluated, Randia ferox, Eugenia myrcianthes, and Garcinia brasiliensis exhibited the highest phytotoxic activity. Regarding the invasive species, Sida rhombifolia showed the greatest sensitivity, with germination rates below 9% in most treatments. Chemical analysis revealed a predominance of phenolic acids - such as cinnamic acid and caffeic acid - compounds associated with allelopathic activity. It is concluded that leaf extracts from these native fruit trees show high potential for use as natural bioherbicides, particularly when obtained via hydroalcoholic extraction, and that their efficacy is linked to the composition and diversity of the phenolic compounds present.