Efeito da aplicação de extrato pirolenhoso,óleo de nim (Azadirachta indica) e acibenzolar-s-metil sobre a interação nematóide-planta hospedeira

Abstract

Adoption of alternative methods for plant parasitc nematode integrated control represents promising strategy due to limitations of traditional methods. The objectives of the present study were: i) to evaluate the efficiency of pyroligneous extract (PE) at four concentrations: 0; 0.01; 0.02; 0.04 (PE/water, relationship v/v) on control of Meloidogyne incognita race 1 in tomato (Lycopersicon esculentum) cv. Santa Cruz Kada Gigante and Rotylenchulus reniformis in melon (Cucumis melo) cv. Amarelo Ouro, under greenhouse, and ii) to determine acibenzolar-S-methyl (ASM) and neen (Azadirachta indica) oil effect on hatching, penetration and reproduction of M. incognita race 1 in melon and sugarcane (Saccharum sp.). In the study with pyroligneous treatments were arranged in a factorial 2 (nematode infested and no infested soil) × 4 (pyroligneous extract concentrations), in completely radomized design with six replications, consisting each experimental unit in a plant per vase. Soilinfestation with 5,000 eggs of R. reniformis or M. incognita per vase was carried out 10 and 15 days after melon and tomato germination, respectively, being applied in soil 50 mL of pyroligneous extract at studied concentration 24 hours after the infestation. Two complementary pulverizations with pyroligneous extract were applied 15 and 30 days after the first one. Evaluations were carried out 55 (melon) and 65 (tomato) days after planting. For both parasites, there were not significant interactions between soil infestation and pyroligneous extract concentrations in relation to plant development and nematode reproduction. Plants cultivated in unimfested soil presented higher (P≤0,05) shoot biomass than those cultivated in infested soil, however, the extract did not suppress R. reniformis and M. incognita reproduction. In the study with ASM and neenoil, it was carried out five experiments, one in laboratory conditions and four under greenhouse. In the laboratory experiment, hatching of M. incognita was evaluated 48 and 168 hours after eggs exposure to ASM (0.05 g/L and 0.50 g/L), neen oil (1 and 2%) and water (control). In the greenhouse experiments, penetration in melon cv. Amarelo Ouro roots of second stage juveniles (J2) hatched under ASM, neen oil and water was evaluated seven days after inoculation. In another experiment, eggs of the parasite, exposed for 172 hours to products and concentrations used earlier, were inoculated in melon and 45 days after it was evaluated reproduction. Other experiments were carried out in sugarcane var. RB 92-759 and SP 813250, being investigated relation between products application and inoculation time, and interactions among products, nematode and arbuscular mycorrhizal fungi (AMF). The results pointed out direct effect of neenoil on M. incognita hatching. Exposuring J2 to ASM decreased nematode penetration in root, but eggs exposure to this compound did not affect nematode reproduction. In contrast, The ASM application in sugarcane decreased nematode reproduction, but it did not affect plant development. AMF suppressed M. incognita reproducton and improved plant development. Neem oil did not affect plant development and nematode reproduction.