Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-10-31T21:23:21Z No. of bitstreams: 1 Disserta??o UEFS Gl?yce de Oliveira.pdf: 2259088 bytes, checksum: 5da18e0a3c0cbe95bc5ed310b3a4d0b0 (MD5) / Made available in DSpace on 2016-10-31T21:23:21Z (GMT). No. of bitstreams: 1 Disserta??o UEFS Gl?yce de Oliveira.pdf: 2259088 bytes, checksum: 5da18e0a3c0cbe95bc5ed310b3a4d0b0 (MD5) Previous issue date: 2016-03-29 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / The Brazilian onion cultivation has significant commercial importance and strong social connotation, because it involves small farmers, most of them belonging to the family nucleus. In the Northeast of Brazil, its cultivation is carried out during the entire year, generating around 60 thousand direct and indirect jobs. Onion crops are vulnerable to diseases and pests, such as Thrips tabaci, major pest affecting these crops, causing damages above 50%. The species Allium cepa presents wide phenotypic variability, allowing the creation of new cultivars for various conditions and requirements. This study aimed to evaluate onion accessions regarding its resistance to T. tabaci, in order to enable the development of cultivars that are resistent to this pest. The experiments were conducted in randomized block design with three replications on the experimental fields at Embrapa Semi?rido, situated in the municipalities of Petrolina/PE and Juazeiro/BA. The results achieved concerning the degree of infestation (DI) in percentage for nymphs and adults were transformed into arc sine of the square root for statistical analysis. Plant architecture traits, bulb productivity and estimated simple correlations among all variables were also evaluated. Five evaluations of thrips populations were carried out after transplanting, each one after seven days. Statistical differences were observed for a number of adults to different evaluations, while the number of nymphs showed no statistical differences. The largest average productions of commercial bulbs were observed for the TX08, IPA 11, Alfa SF C-IX, IPA 10 and Sirius F1 acessions while the Red Creole, Creole Mercosur and Conquest acessions had the lowest productions. The commercial productivity of bulbs had simple negative correlations with nymph DIs in the five phases of evaluations and adult GIs within 22 (n22a) days. Negative correlations between productivity of commercial bulbs x central angle of the plant were observed, indicating that plants with higher bulb production have lower angle on the central leaves. The results of the study show that the resistance mechanism is antixenosis associated with the tolerance mechanism. / A cebolicultura brasileira tem grande import?ncia comercial e tem forte conota??o social, por envolver pequenos produtores rurais, a maioria de n?cleo familiar. No Nordeste brasileiro o cultivo ? realizado durante todo o ano, gerando cerca de 60 mil empregos diretos e indiretos. A cultura da cebola ? vulner?vel a doen?as e pragas, sendo o Thrips tabaci a principal praga da cebola, podendo provocar preju?zos superiores a 50%. A esp?cie Allium cepa apresenta ampla variabilidade fenot?pica, o qual possibilita a cria??o de novas cultivares para diversas condi??es e necessidades. Esse trabalho teve como objetivo avaliar acessos de cebola quanto a resist?ncia ao T. tabaci para possibilitar o desenvolvimento de cultivares resistentes a essa praga. Os experimentos foram conduzidos em blocos casualizados, com tr?s repeti??es, nos campos experimentais da Embrapa Semi?rido, situados nos munic?pios de Petrolina/PE e Juazeiro/BA. Os resultados obtidos do grau de infesta??o (GI) em porcentagem (%) para ninfas e adultos foram transformados para arco seno da raiz quadrada para an?lise estat?stica. Foram ainda avaliados caracteres da arquitetura da planta e sua produtividade de bulbos e estimadas correla??es simples entre todas vari?veis. Foram realizadas cinco avalia??es para popula??es de tripes ap?s o transplantio, a cada sete dias. Foram observadas diferen?as estat?sticas para o n?mero de adultos do tripes para as diferentes avalia??es, enquanto o numero de ninfas do tripes n?o apresentou diferen?as estat?sticas. As maiores produtividades m?dias de bulbos comerciais foram observadas para os acessos TX08, IPA 11, Alfa SF C-IX, IPA 10 e Sirius F1, enquanto os acessos Red Creole, Crioula Mercosul e Conquista apresentaram as menores produ??es de bulbos. A produtividade comercial de bulbos apresentou correla??es simples negativas com GIs de ninfas nas cinco fases das avalia??es e com GIs de adultos aos 22 (n22a) dias. Foram observadas correla??es negativas entre produtividade de bulbos comerciais x ?ngulo central da planta indicando que plantas com maior produ??o de bulbos apresentam menor ?ngulo nas folhas centrais. Os resultados do presente estudo indicam que o mecanismo de resist?ncia ? a antixenose, associado com o mecanismo da toler?ncia.