Abstract
ABSTRACT: The growing of peach in mild winter regions is made viable through the use of genotypes that have low need for cold conditions, and this is one of the main aims of breeding for these regions. Thus, the aims of this study were to estimate genetic parameters, evaluate genetic variability, and select families adapted to mild winter regions in the S1 generation of peach through mixed model methodology (REML/BLUP). For that purpose, 22 populations, 84 families, and 2090 individuals were evaluated for the following traits: bud burst rate (BR), node density (ND), plant height (PH), and trunk diameter (TD). Genetic variability was found for all the traits. Individual heritability in the broad sense was of low and medium magnitudes. The PH trait had positive genotypic correlation of high magnitude with TD. The ND trait had moderate negative genotypic correlation with PH and TD. Clustering by the Tocher method resulted in the formation of six mutually exclusive groups. Considering selection intensity of 25%, simultaneous selection for BR, ND, and TD led to predicted gains of 11.3% for BR, 9.7% for ND, -14.2% for PH, and -14.3% for TD, showing the great potential of the germplasm evaluated.
Highlights
Peach (Prunus persica (L.) Batsch) is an autogamous species, originally adapted to temperate and subtropical zones, that needs a certain accumulation of winter cold after entering in dormancy to have normal flowering and budding
Flowering time is generally used to evaluate the need for cold of the genotypes, and those least demanding in terms of cold are considered; i.e., those most adapted to regions of mild winter are those that achieve a determined flowering rate at an earlier time (PEDRO JÚNIOR, 2007)
Among the parent plants are cultivars with low and medium need for cold released by the Instituto Agronômico de Campinas (IAC) and the Centro de Pesquisa Agropecuária de Clima Temperado (CPACT/EMBRAPA) and selections obtained by the Peach Breeding Program of the Universidade Federal de Viçosa (UFV)
Summary
Peach (Prunus persica (L.) Batsch) is an autogamous species, originally adapted to temperate and subtropical zones, that needs a certain accumulation of winter cold after entering in dormancy to have normal flowering and budding. Flowering time is generally used to evaluate the need for cold of the genotypes, and those least demanding in terms of cold are considered; i.e., those most adapted to regions of mild winter are those that achieve a determined flowering rate (generally 50% open flowers) at an earlier time (PEDRO JÚNIOR, 2007). As the vegetative buds have the need for cold to break dormancy, determination of the budburst rate can likewise be used for the purpose of identifying more adapted genotypes (WAGNER JÚNIOR et al, 2010). That author observed that greater trunk diameter is associated with lower need for cold to break dormancy
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