Reação de clones de batata tolerantes ao calor à pinta preta (Alternaria spp.), podridão mole (Pectobacterium carotovorum), PVY e PVX

Abstract

The potato crop (Solanum tuberosum L.) in Brazil is affected by several biotic and abiotic stresses that limit the productive potential of cultivars used by the producers. Among these factors tolerance to high temperatures deserves to be highlighted, since most cultivars used in the country were improved in temperate regions. In addition to high temperatures another limiting factor is the increased inoculum pressure that occur in Brazil when compared to temperate countries. Among the diseases that affect the potato crop the most important are early blight (Alternaria grandis), soft rot (Pectobacterium carotovorum) and PVY and PVX viruses. This work aimed to evaluate the resistance of clones previously selected for tolerance to high temperatures, to the diseases: early blight, soft rot, PVY and PVX. In addition, clones were evaluated in the field for their agronomic performance. A total of 57 clones of the UFLA potato breeding program were used. Early blight resistance was evaluated in vitro by inoculating mycelial discs onto plantlets obtained from tuber buds. Resistance to soft rot was evaluated by inoculating bacterial suspension in the concentration of 10 7 UFC’s in holes of 6 mm in diameter and 1.5 cm deep made directly into the tubers. Resistance to PVY and PVX viruses were evaluated using molecular markers for the Ryadg and Rx1 alleles, respectively. Genotypes resistant or susceptible to each disease were used as controls. The experimental clones were evaluated in two growing seasons in the field for agronomic traits, in the winter of 2015 and in the dry season of 2016, in a randomized complete block design. More productive and responsive clones than the cultivars were found in the field experiments, demonstrating the greater tolerance to heat stress and responsiveness to mild temperatures. We identified clones that showed good agronomic performance and presented resistance to one or more diseases, and the most outstanding were GRO 01-24, GMR 15-38, GMR 03-54, GMR 11-60. We suggest their use in future breeding programs to increase heat tolerance and resistance levels to the diseases evaluated.