Isolamento, identificação e avaliação de Pochonia chlamydosporia no controle de Meloidogyne javanica e na promoção de crescimento de tomateiro

• Autor(a) principal: Giaretta, Rosangela Dallemole
• Data de Publicação: 2008
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1012
• topic: Pochonia chlamydosporia; Meloidogyne javanica; Fungos nematófagos; Controle biológico; Adubação verde; Tomate; Pochonia chlamydosporia; Meloidogyne javanica; Biological control; Green manure; Tomato; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOSSANIDADE::FITOPATOLOGIA

Twenty-nine isolates of Pochonia chlamydosporia were found in Meloidogyne infested-soils samples of vegetables crops from Viçosa (MG), Mariópolis (PR) and Venda Nova do Imigrante (ES). Among them, 65.52 % were identified as P. chlamydosporia var. chlamydosporia and 34.48 % as P. chlamydosporia var. catenulata. The potential of these isolates including four isolates from Alicante Spain, as biological control agents against Meloidogyne javanica on tomato plants was evaluated under greenhouse conditions. The isolates Pc-1, Pc-2, Pc-3, Pc-4, Pc-9, Pc-10, Pc-21, Pc-24, Pc-28 and Pc-64 were the most efficient in reducing the number of eggs of the nematode per root system. These isolates were re-evaluated and the most efficient were the Pc-64, originated from Alicante Spain, reducing 72.0 % the number of eggs and 10.4 % the number of galls, and the Pc-10, originated from Viçosa Brazil, reducing 60.0 % the number of eggs and 21.3 % the number of galls. The isolate Pc-10 was then used in the following experiments. When this isolate was added into the M. javanica infested-soil 7 days before the transplanting of the tomato seedlings, all chlamydospore rates (5,000, 10,000, 15,000, 20,000 or 25,000 per gram of soil) resulted in reduction of the number of eggs of M. javanica (up to 56 %), but no effect on the number the galls was observed. In the following experiment, the application of 5,000 chlamydospores/g of soil of the antagonist 15 days before the transplanting of tomato reduced in 82 % the number of eggs and in 50 % the number of galls per root system. In another experiment, the isolate Pc-10 of P. chlamydosporia was used with summer cover crops, pearl millet (Pennisetum americanum (L.) Leek) and suriname grass (Brachiaria decumbens Stapf), or winter cover crops, black oat (Avena strigosa Schreb) and oil radish (Raphanus sativus var. oliferus Metzg), for reducing Meloidogyne javanica population in the soil was studied under greenhouse conditions. The cover crops treatments, associated or not with P. chlamydosporia, reduced the root- knot nematode population. P. chlamydosporia Pc-10 alone did not reduce the number of galls or eggs of the nematode in the summer experiment. On the other hand, the fungus alone reduced the number of galls and eggs of M. javanica in the winter experiment. The isolates Pc-3, Pc-10 and Pc-19 promoted the growth of tomato seedlings on coconut fiber substrate, in vitro conditions. The fungal isolate Pc-19 colonized the rhizosphere of tomato plants and produced a large amount of chlamydospores after 15 days. Scanning microscopy revealed that the isolate Pc-10 colonized the rhizoplane of the tomato plants in this same period and the hyphae penetrated the epidermal cells.