Bruno Oliveira Soares

Biologia floral e polinização artificial de pinhão-manso no norte de Minas Gerais

O objetivo deste trabalho foi avaliar alguns aspectos da biologia floral e do sistema reprodutivo de Jatropha curcas, em Janauba, MG. Foram registrados: o numero de flores femininas e masculinas; o intervalo de abertura das flores femininas; e a formacao de frutos por apomixia, autofecundacao, geitonogamia e xenogamia. A proporcao de flores masculinas para femininas foi de 20:1. O intervalo de abertura das flores femininas variou de um a sete dias, conforme o numero delas na inflorescencia. No teste de apomixia, houve formacao de frutos em apenas 5% das flores avaliadas. A percentagem de frutificacao variou de 79 a 88% na autofecundacao manual, na geitonogamia e na xenogamia. Na autofecundacao sem a polinizacao manual a frutificacao foi de 20%, e os frutos formados foram significativamente menores, com numero inferior de sementes por fruto e menor indice de velocidade de emergencia. As sementes foram semelhantes as formadas por polinizacao natural. e possivel a realizacao de cruzamentos controlados em pinhao-manso, e nao ha autoincompatibilidade nesta especie.

Screening of Lycopersicon sp. accessions for resistance to Pepper yellow mosaic virus

The tomato is a crop of great economical importance, however it is susceptible to a large number of pests and diseases, including viral disease for which the best control strategy is genetic resistance. The disease, caused by Pepper yellow mosaic virus (PepYMV) has become a recent problem. Consequently, the idea of this work was to screen 376 accessions of Lycopersicon sp. to find possible sources of resistance to PepYMV. Out of 355 accessions of L. esculentum inoculated with PepYMV, 52 did not express symptoms. However, the virus reached high concentration in the tissues as measured by indirect ELISA, and therefore they were not considered as safe sources of resistance. Among 21 accessions of wild Lycopersicon species, one of L. hirsutum was shown to be resistant, with no observed symptoms. A low concentration of the virus was detected as measured by indirect ELISA. This accession seems to be suitable for breeding programs aiming at incorporating resistance for this disease into commercial tomato cultivars.

Genetic diversity and molecular characterization of physic nut genotypes from the active germplasm bank of the Agricultural Research Company of Minas Gerais, Brazil

Three in vitro experiments were conducted to study the effect of different concentrations of carbon source, salinity and gelling agent on number of new shoots, shoot length, fresh weight, and dry weight of fig (Ficus carica L.) to develop an efficient in vitro propagation method. The results show that there were no significant differences between the three carbon sources regarding number of newly formed shoots and their shoot lengths. However, there were some differences regarding fresh and dry weights. On the other hand, increased salinity concentrations reduced the number of the newly formed shoots, as well as, their shoot lengths. In addition, liquid media produced more shoots compared with the three solidifying agents used. However, there were significant differences among the concentrations of solidifying agents used.

A new methodology for large-scale screening sugarcane resistance to Mahanarva Fimbriolata (Hemiptera: Cercopidae)

Bragantia, Campinas, v. 77, n. 4, p.599-608, 2018 ABSTRACT: The sugarcane spittlebug, Mahanarva fimbriolata (Walker) (Hemiptera: Cercopidae) is an economically important pest of sugarcane in Brazil. The purpose of this study was to develop and validate a greenhouse methodology to screen large sugarcane populations for resistance to spittlebug Mahanarva fimbriolata. A resistant and a susceptible genotype (H. Kawandang and SP81-3250) were first used to determine adequate days after infestation and levels of infestation (number of nymphs per plant) for comparing the resistance of genotypes. Then, 74 sugarcane genotypes including three susceptible and three resistant controls were screened for resistance. The screening method consists in PLANT PROTECTION Article

Host-Plant Resistance to Spittlebugs: A Life-Table Study With Mahanarva fimbriolata (Hemipera: Cercopidae) in Sugarcane Genotypes

Abstract Understanding how host-crop genotypes affect the life history of insect pests is important for developing and using varietal resistance as a pest control measure. Here we determined how wild and cultivated sugarcane genotypes affect key life-history traits and the demographic performance of the root spittlebug, Mahanarva fimbriolata (Stål; Hemiptera: Cercopidae), a major pest of sugarcane, which produces most of the worlds sugar and bioethanol. In the greenhouse, plants of four sugarcane genotypes (two wild and two cultivated) were infested with newlyecloded spittlebug nymphs. A longitudinal life-table experiment was conducted recording developmental time, survival, reproductive output, and longevity of the released spittlebug nymphs. One of the promising sugarcane genotypes was the accession IM76-229 (Saccharum robustum Brandes & Jesw. ex Grassl), which allowed only 20% of nymph survival to adulthood and reduced the spittlebug longevity by 10 d. Such effects on these life-history traits led to a negative intrinsic rate of population growth (rm = –0.002) of the insects, indicating that the test population would eventually go extinct on this sugarcane genotype. An opposite trend (i.e., population growth) was obtained for the insects raised on Saccharum spp. (SP81-3250 and SP80-1816 cultivars) and Erianthus arundinaceus (Retz) Jeswiet (Kawandang genotype).These results show that S. robustum IM76-229 genotype has resistance traits that drastically reduce spittlebug population growth and indicate that it can be used in breeding programs aiming to develop sugarcane cultivars with resistance to spittlebugs.

Effect of Mahanarva fimbriolata (Hemiptera: Cercopidae) Attack on Photosynthetic Parameters of Sugarcane Genotypes of Contrasting Susceptibility

Abstract The aim of this study was to compare the effect of spittlebug Mahanarva fimbriolata Stål (Hemiptera: Cercopidae) on photosynthetic parameters of both a susceptible (SP81-3250) and a resistant (H.Kawandang) sugarcane genotype. In the first assay, the susceptibility level of genotypes to spittlebug was confirmed by comparing damage score and chlorophyll content of the plants. In the second assay, the effect of spittlebug nymphs on photosynthetic characteristics was assessed using the following parameters: Net photosynthetic rate (A), carboxylation efficiency (A/Ci), stomata conductance (gS), transpiration (E), electron transport rate (ETR), maximum quantum yield of Photosystem 2 (PSII) (FV/FM), effective quantum yield (Y(II)), photochemical quenching (Y(NPQ)), and nonphotochemical quenching (Y(NO)). Spittlebug nymphs affected the photosynthetic process of the susceptible genotype SP81-3250 by decreasing the Chl content, ETR, FV/FM, andY(II). However, this genotype was able to maintain A probably due to its ability to maintain stomata aperture, increase the carboxylation efficiency of Rubisco, and dissipate excess energy through the xanthophyll cycle, as Y(NPQ) increased under the spittlebug attack. On the other hand, the spittlebug did not affect Chl content and FV /FM of the H.Kawandang genotype. Furthermore, H.Kawandang increased A to compensate for the sink demand by the spittlebug by increasing stomatal aperture and carboxylation efficiency and increasing efficiency of the photochemical apparatus in converting light energy into chemical products. We can conclude that the feeding habits of spittlebug nymphs have different impacts on photosynthesis of susceptible and resistant sugarcane genotypes.