Pré-melhoramento visando resistência à requeima em tomateiro

• Autor(a) principal: Laurindo, Bruno Soares
• Data de Publicação: 2013
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4613
• topic: Solanum lycopersicum L.; Banco de germoplasma; Pré-melhoramento; Fonte de resistência; Análise dialélica; Phytophthora infestans; Solanum lycopersicum L.; Germplasm bank; Pre-breeding; Source resistance; Diallel analysis; Phytophthora infestans; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The tomato production is considered a high risk economic activity, and of great agronomic complexity mainly because of the high number of pathogens that causes diseases in the culture. Among the pathogens of greatest importance, there is the oomycete Phytophthora infestans (Mont.) de Bary, causing late blight, which is considered the most destructive disease of tomato. There are no commercial tomato cultivars resistant and the control of this disease is highly dependent on the use of fungicides. Considering that the tomato is one of the most studied crop in genetic terms, the lack of resistant cultivars in the market reflects the difficulty in working this trait in breeding programs. The objectives with this present study was to select sources of resistance to late blight among accessions of Solanum lycopersicum, and estimate the overall and specific ability of combining six tomato accessions of Solanum lycopersicum selected for resistance to late blight, aiming at the selection of potential genitors for pre-breeding for resistance to this disease. Two experiments were carried out. In the first, twelve accessions of S. lycopersicum, from the Vegetable Germplasm Bank of the Federal University of Viçosa - BGH - UFV (BGH-973, BGH-1025, BGH- 2017, BGH-2093, BGH-2095, BGH-2102, BGH-2117, BGH-2127, BGH-2130, BGH- 2332, BGH-2333 and BGH-2343) were evaluated in a randomized block design with three replications. For the evaluation of the resistance, the plants were inoculated with a mixture of sporangia of P. infestans, in the concentration of 5x103 sporangia mL-1 , collected in different regions of the Zona da Mata Mineira. It was evaluated the percentage of plant tissue affected by the disease, or the percentage of severity, evaluated in the form of area under the disease progress curve (AUDPC). The accessions BGH-2102, BGH-2117, BGH-2127, BGH-2130, BGH-2332 and BGH-2343 obtained average values of AUDPC lower than the resistant controls, and were selected as a source of resistance to late blight. The selected accessions as resistant to late blight were used in a second experiment, where a balanced diallel of half table were realized, and fifteen F1 s hybrids were obtained. The six accessions of S. lycopersicum, BGH- 2102, BGH-2117, BGH-2127, BGH-2130, BGH-2332 and BGH-2343 together with the fifteen F1 s hybrid were evaluated in a randomized block design with three replications. For the evaluation of the resistance, the plants were inoculated with a mixture of sporangia of P. infestans, in the concentration of 5x103 sporangia mL-1 collected in different regions of the Zona da Mata Mineira. The percentage of plant tissue affected by the disease, or the percentage of severity, presented in the form of area under the disease progress curve (AUDPC) were evaluated. The diallelic analysis was carried out according to the model of GRIFFING (1956). Observed existence of additive genetic variability between the genitors and the predominance of additive gene effects involved in determining the AUDPC, besides the existence of bidirectional dominance deviations in the control of the character. The diallel analysis was efficient in selecting genitors aimed at a pre-breeding of resistance to late blight, highlighting the accessions BGH- 2117, BGH-2127 and BGH-2343 with the greatest frequency of favorable alleles and divergent, thus they can be included in crossings aiming the pre-breeding for resistance to late blight.