Fontes de resistência à murcha de Fusarium raça 1 e Sigatoka-negra entre híbridos de bananeira

Abstract

Bananas are among the most consumed fruits worldwide. In Brazil bananas belonging to the Prata subgroup are most representative occupying almost 60% of the cultivated area due to its good acceptability in the internal market. One of the main challenges to banana production is the attack of pathogens such as virus, bacteria and fungi. The main threatening fungi diseases are fusarium wilt, caused by Fusarium oxysporum f. sp. cubense and black Sigatoka, with Pseudocercospora fijiensis as its main pathogen. The objectives of this work were to challenge new diploid and tetraploid hybrids of banana in terms of resistance to wilt of Fusarium race 1 (FOC) and Pseudocercospora fijiensis,under field conditions aiming to select resistant hybrids for use in crosses or recommendation to banana growers. The scores for external and internal symptoms were transformed into incidence index for fusarium wilt. In addition, the hybrids were characterized agronomically to be used in the indexes by selection gain. Four selection criteria were considered for evaluation of Black Sigatoka: during the total period of the experiment; only in the summer period; only in the winter period; and in the emission and harvest of the clusters, using their estimated average ID's and AACPD's. Three improved diploids were selected for presenting resistance to Foc race 1 and agronomic characteristics of interest. A Prata-type and a Pacovan hybrid were resistant to Foc race 1 and presenting agronomic characteristics of interest. A new Silk-type hybrid presented resistance to Foc race 1 and agronomic characteristics superior to the BRS Princesa cultivar. The selection of the hybrids was more effective when concentrated in the winter and evaluation of symptoms in four number three leaves. Three improved diploids presented qualitative resistance and two quantitative resistance. A Prata-type tetraploid hybrid had quantitative resistance and potential for use by banana growers.The identification of the best season for Black Sigatoka evaluations together with the use of early selection criteria, in order to accelerate the development of cultivars to make them available to the farmers, helps to gain time for the evaluation of cultivars and the availability of these materials to the consumer market, thus classifying as novel and innovative, in addition to contributing to the advancement of studies of these diseases and the genetic improvement of banana