Capacidade de combinação e seleção de clones de batata visando resistência à podridão mole

Abstract

Several diseases negatively affects potato yield in Brazil. Soft rot, caused by Pectobacterium spp., is one of the most important disease in potato crop causing tuber rot at field and storage conditions. Its control is difficult once there are no efficient chemical products. Cultural practices such as adequate plant nutrition and water management are somehow effective in reducing soft rot in the field but genetic resistance has a major role in soft rot control by identifying clones with considerable genetic resistance and good agronomic traits. In this context, six clones from the potato-breeding program (PROBATATA) at Federal University of Lavras (UFLA) were crossed in order to find clones with high resistance levels to Pectobacterium carotovorum subsp. carotovorum. In 2017, a field experiment was conducted for evaluating clone’s agronomic performance, in augmented block design with 356 clones and five check treatments. After harvesting, we evaluated yield and specific gravity. Later, a laboratory experiment was conducted to evaluate the clone’s reaction to soft rot. This experiment was set in the Bacteriology Laboratory at Phytopathology Department at UFLA. Genotype effect was significant for total yield and specific gravity, besides the diameter and depth of lesions caused by the pathogen. The diallel analysis showed significance for the general combining ability (GCA) for the injury depth and the specific combining ability (SCA) for the diameter, considering 5% of probability. The parents RVS 06-37, PRM 348 and CBM 09-10 contributed effectively for the resistance enhancement according to their GCA and the families 3, 5 and 7 showed the best estimates for SCA. Clone’s classification was based on the diameter means of the control treatments, discriminating clones into four categories. MOF 03-18, 12-22 and 13-27 clones were classified as resistant and showed high means for yield and tuber dry matter.