Efeito do biofertilizante Agrobio no controle de Meloidogyne javanica na cultura do tomateiro

Abstract

Biofertilizers, in addition to their function as an organic fertilizer, acts as an agent to control pests and diseases. Considering that the control of nematodes of the genus Meloidogyne ssp. through nematicides is not attractive for agriculture due to its high costs and high toxicity, it is necessary to search for a more viable alternative for the management of these phytopathogens In this sense, the use of biofertilizers, as biocontrol, becomes a very viable tool, but it has been gaining little prominence. This work aimed to evaluate the control potential of the Meloidogyne javanica species in tomato crops through the application of the agrobio biofertilizer in the soil. Initially, the phytotoxic effects on seeds and seedlings were evaluated to determine the optimal concentration. The indices were evaluated after 15 days: relative percentage of seed germination (RSG); the relative percentage of the length of the roots (RRG), and the germination index (GI). The phytotoxicity in seedlings was evaluated using the phytotoxicity scale, with periodic evaluations twice a day for 14 days. Then, tests in vitro were set up to verify the effect concentration on the mortality and hatching of Meloidogyne javanica eggs. The mortality and hatching tests were set up in DIC with six treatments and six replications. The treatments consisted of five concentrations of Agrobio biofertilizer (0%, 5%, 10%, 15%, 20% and 25%). In the mortality test, each plot received approximately 50 second-stage juveniles (J2). Mortality was assessed three times (24, 48, and 72 h). Egg hatch assay counted 50 eggs of M. javanica per plot. Plate readings were taken for 10 days, every 24 h. Soon after that, tests for parasitism of M. javanica were performed on the tomato plant cv Santa Clara. The experimental design used was in DBC, with a 3x7 factorial scheme with six replications, using three levels of M. javanica inoculum (500, 1000, and 2000 eggs per plant), seven application schemes (7DAT, 1DT, 15 DAE, 30 DAE, 45 DAE, 60 DAE and control without application) in soil. The parameters evaluated were: egg mass index (IMO); Gall Index (GI); Root system weight (PR); Number of eggs per gram of root (NGR) and Reproduction factor (FR). In addition, agronomic parameters were evaluated such as Plant height (ALT); Rod diameter (DC); Number of leaves (NF); Total Fresh Matter (MFT); Dry matter of leaves (MSF); Stem dry matter (MSH), Total dry matter (MST) of the shoot. There was a phytotoxic effect in the application of seeds at the concentrations tested, thus interfering with the percentage of germinated seeds and root length. In the seedling phase, no phytotoxicity effect was observed. The in vitro tests, from 72 h, the biofertilizer showed a nematicidal action on J2 mortality and an inhibitory effect on the egg hatching process. The three inoculum levels tested in different application schemes of Agrobio biofertilizer did not show significant effects in relation to egg matter index, gall index, root weight, number of eggs, and reproduction factor. We also not observed a significant effect of the product and inoculum level in relation to the agronomic parameters. These results demonstrate that the use of Agrobio biofertilizer, under the conditions tested, has no nematicidal effect on M. javanica.