Extrato de folhas de juá (Ziziphus joazeiro Mart) no controle de Meloidogyne javanica na cultura da alface

Abstract

Lettuce is one the vegetables mostly consumed by the Brazilian population and is susceptible to the infection by nematodes of the genus Meloidogyne, which cause significant yield losses. Non-chemical management strategies such the medicinal plant control have high potential to control plant parasitic nematodes. This study aimed to evaluate the effect of aqueous extract of juá in controlling the root-knot nematode Meloidogyne javanica in lettuce plants. In vitro bioassays were conducted with 100 μL of an aqueous suspension containing 100 juveniles (J2) of M. javanica and 900 μL of aquose extract. The treatments consisted of nematode immersion for 24 and 48 hrs in extract diluted in water to the final concentrations of 5.0%, 10.0%, 15.0%, 20.0% and 25.0% and the control treatment without the extract (0%).Under greenhouse conditions, 1000 juveniles of M. javanica were inoculated in lettuce plants grown in pots, and after one week, 100 mL of the aqueous extractin the concentrations mentioned above were applied into the soil, with distilled water being used for the control treatment. Forty days after inoculation, plants were harvested and evaluated the dry mass of shoot and roots, the number of galls and egg masses, nematode final population and reproduction factor. All concentrations of the aqueous extract presented nematicidal effect after 48 hrs of nematode exposure. A mortality rate of 75.0% of M. javanica juveniles was observed for theextract at a concentration of 25.0%. There was an increase inroot dry mass for all concentrations of the extract.The aqueous extract showed a nematicidal effect with a reduction of 63.0% and 85.2% in the number of galls per plant and per gram of roots, respectively. There was a reduction in the number of egg masses per plant and per gram of roots of 74.7% and 90%.The final population of nematodes decreased dramatically as the extract concentrations increased. Future studies should be conducted to test the nematicidal effect in lettuce plants under field conditions.