Diferenças morfofisiológicas, alométricas e anatômicas de dois genótipos contrastantes de cana-de-açúcar a ninfas de cigarrinha das raízes (Mahanarva fimbriolata)

• Autor(a) principal: Melo, Cristiane Gamarano de
• Data de Publicação: 2014
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1250
• topic: Cana-de-açúcar - Melhoramento genético; Cigarrinha (Inseto); Mahanarva fimbriolata; Saccharum spp.; Erianthus; Cane sugar - Genetic improvement; Leafhopper (Insect); Mahanarva fimbriolata; Saccharum spp .; Erianthus; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

This study aims at analyzing the differences morphophysiological, allometric and anatomical ones between two sugarcane contrasting genotypes, Kawandang (tolerant) and SP813250 (susceptible), when subjected to spittlebug s nymphs attack (Mahanarva fimbriolata). The morphophysiological and allometrical technical features were evaluated at four different stages: at seven, fifteen, thirty and thirty-seven days after the sugarcane had been exposed, or not (control group), to spittlebug s nymphs. Anatomical features of both sugarcane genotypes were measured seven days after treatment had begun. The exposure to spittlebug s nymphs resulted in significant reductions of stomatal conductance, transpiration, and leaf greenness degree for SP813250 genotype in comparison to the Kawandang genotype. Internal carbon concentration levels did not differ significantly throughout the period of testings. However, the levels were significantly higher on the exposed SP813250 variety in comparison to those measured in the control group for the same genotype. From the first readings, the damage caused by the nymphs on the leaves always received a higher visual damage assessment when the genotype considered was the SP813250, in comparison to the control group of that genotype. In its turn, the Kawandang s genotype visual damage assessment got a different result from the control group only at the thirtieth day. In both genotypes, the nymphs attack resulted in stoppage of fresh weight gain by the shoots. On the other hand, there was a stoppage in the accumulation of dry mass in the SP813250 genotype and a significantly increase of dry mass in the Kawandang genotype. SP813250 has shown a significant increase of both dry and fresh mass of its roots during the time of interaction with the plague, whereas the Kawandang type showed no significant variations in those variables. The anatomical analysis of the roots has shown presence of aerenchyma in the cortex of SP813250 genotype, contrariwise to the Kawandang genotype, whose cortex cells were compact and well-organized. The results found in this study show how strong the tolerant genotype is in responding to the attack of M. fimbriolata nymphs, and emphasize the morphophysiological, allometric and anatomical differences between the two genotypes. They could help genetic improvement programs to get a sugarcane variety that is tolerant and/or resistant to spittlebug s nymphs.