Allelopathic potential of methanolic extract from roots of Piper tuberculatum

vol. 1, 2019 - 117617
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Allelopathy is the process by which plants, algae, bacteria or fungi, through the production and release of specialized metabolites, positively or negatively influence the development of other living beings1. Piper tuberculatum¸ popularly known as “pimenta-longa” is a shrubby plant found in the Americas and the Antilles, reported as having insecticidal, antidiuretic and analgesic activities2. The search for new solutions for weeds control is of great relevance, as different crops are continuously developing resistance to agrochemicals. With this focus, the allelopathic potential of the methanolic extract of P. tuberculatum roots was evaluated against target plants weeds, Bidens pilosa (“picão-preto”) and Euphorbia heterophylla (“leiteira”). The seeds of B. pilosa and E. heterophylla were previously selected and sanitized in an ultraviolet chamber (30 min). In each bioassay (triplicate), each petri dish was covered with qualitative filter paper received 3 mL of solution and 10 seeds. Dilutions of 200, 300, 400, 500 and 600 ppm of methanolic extract of P. tuberculatum root were added to the petri dish. The bioassays were conducted in a BOD chamber under controlled conditions at 30 °C (day) and 25 °C (night) with 12 hours of photoperiod. Seed germinations were recorded daily for 7 days and the following variables were determined: germination speed index (GSI), average germination speed (AGS), percentage germination (PG) and percentage of abnormal (PAS) and dead (DS) seedlings. The results of all variables were subjected to normality analysis by the Shapiro-Wilk test, evaluated by Tukey test and ANOVA in the Statistica 10 program. In case of B. pilosa, the concentration of 500 ppm of extracts decreased GSI (5.47), AGS (0.38) and PG was 56.6%, being higher only than 600 ppm (53.3%). Compared to the control with GSI of 10.82, the AGS of 0.45 and the PG of 70%, what pointed that extract of P. tuberculatum influenced the germination of this species. In E. heterophylla, the control GSI was 7.52, increasing in concentration from 200 ppm to 11.60 and then decreasing to its lowest value at 500 ppm (6.82). For AGS the lowest value was obtained with 500 ppm (0.39) (0.59 for control). The PG of this species, between 40 and 50%, increased at the concentration of 200 ppm (63.3%). Thus, it can be seen that, for these target plants, P. tuberculatum solution may have positively influence using small concentrations, as commonly occurs in allelopathic tests, and negatively at higher concentrations (500 ppm). In the 7th day of experiment parameters of PAS for B. pilosa (18%) (6% for the control) and the DS had the highest value at 500 and 600 ppm (10%). In E. heterophylla, PAS gradually decreased showing the highest value at 200 ppm (15%) and DS showed 8% in control and 12% at 500 ppm. From these results, it is observed that the methanolic extract of P. tuberculatum roots has allelopathic potential on the seeds of B. pilosa and E. heterophylla, reducing germination in number of germinated individuals and in the speed in which this process occurs. The allelopathic potential of this extract on the weeds will be further evaluated using pure compounds isolated from roots of P. tuberculatum.

  • 1 Câmpus de Pato Branco / Universidade Tecnológica Federal do Paraná
  • 2 Instituto de Química de São Paulo / Universidade de São Paulo
Allelopathy; Plants weeds; Seed germinations