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Resistance of Brazilian sugarcane cultivars to Ceratocystis paradoxa, the causal agent of pineapple sett rot.

Juliana Uzan: Federal University of São Carlos

<div>Sugarcane is a versatile and renewable crop used in Brazil to produce sugar, ethanol, and bioelectricity. The high demand for its raw materials has forced all year-round planting. Pineapple sett rot has become a major problem of sugarcane seed pieces during winter when low soil temperature and moisture delay germination and setts decay before bud germinates. Resistant cultivars is the ideal method to control this disease, and reports from other countries indicated a wide range of susceptibility among cultivars. Therefore, this study aimed to examine the reaction of four of the most important Brazilian sugarcane cultivars to pineapple sett rot. Ten buds of each cultivar (RB855156, RB867515, RB92579, RB966928) were planted in a plastic tray of 2,700 cm<sup>3</sup> of substrate and contaminated with 0.04, 0.4, 4, 40<sup>-3</sup> and compared to uninoculated control. The experiment was kept at 25°C, photoperiod of 12h, and 25% of soil humidity in a completely randomized design with four replications for 28 days, when germination failure due to the disease was evaluated. Percentage of germinated buds was submitted to analysis of variance and to the Tukey test using software ASSISTAT. RB92579 was the most susceptible cultivar, being the first to have bud germination significantly affected as pathogen level increased (4<sup>-3</sup>). On the other hand, RB867515 showed the highest resistance, with no significant difference to uninoculated control in all pathogen levels.</div>