Ação de cumarinas sintéticas sobre crescimento inicial e cariologia de plantas superiores plantas superiores

Abstract

The present work aimed to understand the allelochemical effect of three coumarins derived from Eugenol [Formileugenol (CA); Formyldihydroeugenol (CA1) and Ortho-vanilla (CA2)] on physiological and cytogenetic processes of Lactuca sativa L. and Bidens pilosa L. Each coumarin was dissolved in a distilled water solution, to obtain a stock solution with a concentration of 5,000 μg.mL-1

, after obtaining the stock solution, each coumarin was

dissolved, obtaining concentrations of 400 μg.mL-1, 800 μg.mL-1

and 1600 μg.mL-1 , plus the control concentration (distilled water). Phytotoxicity and cytotoxicity experiments were carried out. For the phytotoxicity experiment, the following parameters were evaluated: germinability (G%), germination speed index (IVG), number of normal seedlings (NPN), root elongation (AR), shoot length (CPA) and fresh biomass (BF). The post-establishment physiological aspects of the seedling were fresh biomass (BF) and dry biomass (BS). The allelopathic index (RI) was evaluated. For the cytotoxicity experiment, the seedlings were grown in the same molds used in phytotoxicity and the root tips were collected and stored in Carnoy. Cytological slides were prepared and subjected to evaluation of mitotic index (MI) and the possible occurrence of chromosomal abnormalities (CA). The design was entirely causalized (DIC), with 3 replications, with a 3x4x2 factorial (3 molecules, 4 concentrations and 2 biotests). The data obtained were subjected to Analysis of Variance (ANOVA) and the means compared using the Scott-Knott test at 5% significance using the Sisvar version 5.6

program. The analyzes made it possible to verify the allelochemical efficiency of CA for post- emergence patterns. This molecule at a concentration of 1600 μg.mL-1 showed a significant

effect on the parameters %BF, IVG, AR, CPA, NPN and RI, in the two biotests tested, at a concentration of 1600 μg.mL-1

. For cytogenotoxicity parameters, none of the molecules, at any concentration, promoted significant karyological changes. Therefore, it is concluded that the Formileugenol (CA) molecule has sufficient characteristics to support research aimed at controlling invasive species, and could become an active principle for alternative herbicides to control these invasive plants.