Heritability and segregation of resistance to brown rot in peach fruits

Brown rot caused by the fungus Monilinia fructicola is the most important disease in peach production areas of Brazil. The increased concern with the environment, consumers and workers' health, emphasizes control strategies other than fungicide applications. Among them genetic resistance is the most efficient. However, availability of resistant genotypes is still limited. Thus the main objective of this work was to seek sources of brown rot resistance, as well as to study the segregation, estimate the heritability and verify the possible existence of maternal effects. Heritability of brown rot resistance was investigated in peach fruits of several genotypes from the Embrapa peach breeding program. Sixteen progenies and 20 parents were evaluated. Disinfested fruits were wounded with a microsyringe and inoculated by deposition of a 10 μL drop of a 2.5×10⁴ spores mL^‑1 of M. fructicola. The fungus inoculum was obtained from a culture originated from peach mummies from four different sites. After inoculation, the fruits were incubated under controlled conditions for 72 h, before evaluation of lesion size and sporulation. High phenotypic variability and transgressive segregation were observed for brown rot resistance in fruits. Several genotypes showed similar resistance as 'Bolinha', the standard Brazilian cultivar for resistance. The heritability of brown rot resistance in fruits (diameter of the lesion and sporulation), was medium. Parental selection based on phenotype, enables a medium genetic advance for brown rot resistance. The selections Conserva 947 and Conserva 1600 were the parents with higher brown rot resistance (similar to 'Bolinha'), with the potential of passing this trait to their offspring.