Assessment of resistances to multiple pathogens in experimental sweet pepper hybrids

The aim of this study was to assess resistance to some of the major sweet pepper pathogens [Phytophthora capsici, Pepper yellow mosaic virus (PepYMV) and Meloidogyne incognita] in a group of experimental hybrids and their respective parental lines, and to identify hybrids possibly resistant to all three pathogens. Ten parental breeding lines, thirty experimental hybrids and seven commercial controls (Konan-R, Magali-R, Martha-R, Stephany, Mallorca, Magnata Super and Criollo de Morelos-334) were used. Each experiment was set up in a randomized complete block design with three replications and plots consisting of 16 plants. For assessment of resistance to P. capsici and PepYMV, the percent of asymptomatic plants was considered. In evaluating reactions to M. incognita, both the nematode reproduction index and the nematode reproduction factor were calculated. Five hybrids were found with resistance to all three pathogens. For all three pathogens, there was evidence that hybrids with two resistant parental lines showed slightly higher levels of pathogen resistance than those with only one resistant parental line. © 2017, Sociedade de Olericultura do Brasil. All rights reserved

Seleção para resistência de genótipos de cenoura aos nematóides-das-galhas Selection for carrot genotypes resistance to root-knot nematodes in field and greenhouse

Foi verificada a relação entre caracteres avaliados em campo e casa-de-vegetação, relativos à avaliação de genótipos de cenoura quanto à resistência ao nematóide-das-galhas (Meloidogyne spp.), visando identificar quais caracteres possibilitam a diferenciação entre os genótipos e verificar a possibilidade de avaliação apenas em um ambiente ou a eliminação de caracteres que apresentem correlação alta. Avaliaram-se 38 progênies da população '0812518' e 31 progênies da população '0812519', além das cultivares Brasília e Kuronan como testemunhas tolerante e suscetível, respectivamente. Em campo naturalmente infestado por uma mistura de Meloidogyne incognita raça 1 e Meloidoigyne javanica, a seleção para resistência ao nematóide-das-galhas foi realizada com base na menor porcentagem de infecção na raiz principal dos genótipos de cenoura, rendimento de raiz e o fator de reprodução, enquanto que em casa-de-vegetação, para cada uma das mesmas espécies de nematóides e também para a mistura de ambas, foi medido o índice de galhas e índice de massa de ovos. Verificou-se que não houve possibilidade de seleção em apenas um dos ambientes testados ou a eliminação de caracteres, indicando que para a obtenção de cultivares mais produtivas e mais tolerantes é necessária a seleção combinada nos diferentes caracteres e ambientes. Para o experimento realizado em campo foi possível diferenciar os genótipos apenas para o rendimento de raiz. No experimento em casa-de-vegetação, para todos os caracteres foi possível identificar genótipos superiores. Porém, as médias das populações não foram melhores que a testemunha 'Brasília' da qual estas se originaram, confirmando a necessidade da busca por métodos mais eficientes de seleção.<br>We verified the relation among the evaluated characters in field and greenhouse, concerning to the evaluation to root-knot nematode (Meloidogyne spp.) for the carrot crop, to identify for which ones it is possible to differentiate among genotypes and to verify the possibility of evaluation only in one environment or the elimination of characters with high correlation. Thirty eight and thirty one families from the carrot populations '0812518' and '0812519', and the cultivars Brasília and Kuronan as tolerant and susceptible standards, respectively, were evaluated. In a field whose soil was naturally infected by a mix of Meloidogyne incognita race 1 and Meloidogyne javanica, the selection to resistance to root-knot nematode was based on lower percentage of infection in the root, of the major genotypes of carrot production in t/ha and reproduction factor; and in greenhouse, to each one of the same nematode species and too for a mix of both, was evaluated the index of gall and index of egg mass. There is no possibility of selection in only one condition or the elimination of some characters, indicating that, to obtain more yielding and more tolerant cultivars, the combined selection in the various characters and environments are necessary. In the field experiment, it was only possible to differentiate the genotypes for root yield. In the greenhouse, it was possible to identify superior genotypes for all characters tested. However, the average population was not better than the 'Brasilia' standard that originated these populations. This result confirms the necessity to search for more efficient methods of selection