Nematóides parasitando guandu
Nematode parasites of pigeon pea
Luiz Gonzaga E. Lordello; Hermano Vaz de Arruda
SUMMARY
A crop rotation experiment, carried out at Ribeirão Prêto Experimental Station, State of S. Paulo, was severely damaged by root-parasitic nematodes. In a first rotation, in which pigeon pea (Cajanus cajan (L.) Millsp.) was planted for twro years and followed by rice, the pigeon pea plants were badly injured. In a second rotation consisting of just one year of pigeon pea cultivation followed by rice, the pigeon pea plants were not so severely affected as in the former case and showed normal growth. It is assumed that a great increase in the nematode population resulted from the cultivation of its suitable host plant (pigeon pea) during the two-year interval, with severe effects on the second-year crop.
Two parasitic nematodes were obtained from the pigeon pea roots and their surrounding soil: Xiphinema campinense Lordello and Meloidogyne javanica bauruensis Lordello, the latter recently described as a parasite of soybean at Bauru, also in the State of S. Paulo.
Xiphinema campinense has already been reported as an ectoparasite of pigeon pea in Campinas, the population at hand differing from that on which the original description was based only in having a very fine striatum in the hypodermis of the caudal region. The lateral fields showed to be obscure, being one-third as wide as the body width; a single series of pores connected with round cells of the lateral chords could be seen along the fields. A rather outstanding feature of the species, well observed in this population, is the strong development of the protrudor muscles of the odonto-stylet; these muscles are sometimes so developed as to obscure the stylet outline. These informations are reported here in order to complete the species original description.
M. javanica bauruensis produces on pigeon pea roots rather small galls, whose diameter is only from two to three times the normal diameter of the roots. It has been mentioned in several papers that in some plants the root-knot nematodes break through the root surface so that the egg-producing females protrude from the root and may be seen with the aid of a hand lens as globular bodies with yellowish or brownish egg masses attached to them. This is the type of infection occurring in pigeon pea roots invaded by M. javanica bauruensis. Under such a condition, this parasite is even more injurious than in those cases where smooth and uncracked galb without necrotic: tissues are formed. As it is known, this i3 due to the fact that roots cracked or opened by the action of a root-knot nematode are at once invaded by several secondary agents, including other nematodes, fungi and bacteria, usually hading to quick decay.
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Recebida para publicação em 30 de novembro de 1955.
Datas de Publicação
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Publicação nesta coleção
12 Maio 2010 -
Data do Fascículo
1956
