Brazilian peach breeding programs have been established to improve peach [Prunus persica (L.) Batsch] production, yield consistency, quality, and disease resistance. Every year several genotypes are selected and their traits must be assessed. This study aimed to evaluate adaptability and stability of fruit set and production of peach genotypes in a subtropical climate, using the GGE biplot methodology. The experimental design was completely randomized with three replicates (trees) in a factorial arrangement of 29 × 3 for genotype and growing season,

This study aimed to evaluate adaptability and stability for leafing of peach genotypes in a subtropical climate. The design was completely randomized with three replicates (trees) and five branches per replicate in a factorial arrangement of 34 × 4 for genotypes and years, respectively. The beginning of budburst (5%), final budburst (75%) and fruit-bearing shoots formed at 45 days after the end of the budburst were evaluated for four years (2007-2010). The number of hours of temperature below 7.2 • C or 12 • C or above 20 • C from May to August was recorded. Adaptability and stability analyses were performed using GGE biplot methodology.

Nowadays, despite of being a typically temperate fruit crop, peach is found in subtropical and even tropical altitude zones, due to breeding efforts. Genetic knowledge and phenotypic and environmental parameters directly or indirectly influence the characters of economic importance in peach, and they are of great importance for breeding programs orientation. The aim of this study was to estimate heritability of a color shade character of peach flesh, measured by the Hue angle, chroma and lightness to evaluate its distribution in the populations, testing the possible existence of maternal effect. Results showed that parameters related to color shade of peach flesh have a medium heritability. Parents selection based on phenotype allows a medium genetic improvement for the mentioned character. This heritability is predominantly additive, without maternal effect. The Hue angle is the correct parameter to be used to classify and study yellow-flesh peaches and nectarines in relation to their color shade. However, the multivariate analysis of principal components, using the three parameters Hue angle, chroma and lightness, is an alternative of high accuracy.

rEsumo-A embriocultura permite desenvolver embriões de sementes que não germinariam em condições convencionais de semeadura. Esta técnica é útil na obtenção de cultivares de pessegueiro com maturação precoce. o uso de genótipos diferentes faz com que sejam necessários ajustes ao protocolo. o objetivo deste trabalho foi testar quatro tipos de meio de cultura (WPM, sH, Ms e sBH), em duas concentrações de sacarose (1,5 e 3%), a fim de avaliar qual a melhor combinação para o cultivo de embriões de pessegueiro in vitro. os genótipos utilizados como modelo do estudo foram 'Conserva 1129', em 2009, e 'Conserva 844', em 2010. Avaliaram-se a germinação, o desenvolvimento na fase in vitro, o comprimento de caule, número de folhas, sobrevivência das plântulas e formação de rosetas, em casa de vegetação. Considerando as condições em que os experimentos foram conduzidos, pode-se concluir que a estratificação e a germinação de embriões imaturos de pessegueiro in vitro melhoram quando realizadas em meios com maior concentração salina e de sacarose. termos para indexação: Prunus persica, pêssegos de maturação precoce,embriocultura, resgate de embriões.in vitro stratification of pEacH zigotic EmbrYos in diffErEnt culturE mEdia and sucrosE concEntrations abstract -The embryo culture technique allows developing embryos of the seeds that could not germinate in conventional planting conditions. This technique is very useful to improve breeding programmes of earlymaturing peach cultivars. The use of different genotypes makes to be necessary adjustments to the protocol. The objective of this study was to test four culture medium (WPM, sH, Ms and sBH) and two sucrose concentrations (1.5 and 3%) to find the best combination for growing peach embryos in vitro. The genotypes used as a model were 'Conserva 1129', in 2009, and 'Conserva 844', in 2010. There were evaluated the germination (quality of germination and percentage of normal germination) and in vitro development (roots and steam length, and number of leaves and secondary roots); the stem length, leaf number, percentage of embryo survival and formation of rosettes, during greenhouse establishment. Considering the conditions under which the experiments were conducted, it can be concluded that in vitro stratification and germination of immature peach embryos were improved when performed in media with higher salt concentration of sucrose. index terms: Prunus persica, early-maturing peach, embryo culture, embryo rescue. introdução dentre os métodos mais aplicados no melhoramento genético do pessegueiro, destaca-se a hibridação, seguida pelo plantio das sementes originadas deste processo (MonET;BAssi, 2008). Porém, sementes oriundas de frutas de maturação precoce possuem baixa porcentagem de germinação atribuída ao reduzido desenvolvimento do embrião. Cultivares que apresentam maturação inferior a 100 dias têm a maturação da fruta antecedida à do embrião, resultando na redução de germinação. Quando o ciclo da fruta (floração a colheita) estiver compreendido entre 75 e 90 dias, é necess...

Here, we reviewed both endogenous and exogenous factors involved in the processes of flower bud formation and flower development in peach, analyzing how they can be affected by climatic change in temperate zones, explored the expansion of peach to tropical or subtropical zones. The process of flower bud formation in peach differs between low winter chilling and temperate conditions. Although the main steps of flower development are maintained, the timing in which each one occurs is different, and some processes can be altered under low winter chilling conditions, with a great impact on fruit production and crop management. Further studies on flower bud induction and differentiation under warmer conditions are fundamental for addressing the alterations in flower bud development that negatively impact on next season’s harvest. In the future, horticulturalists and scientists will face several challenges, mainly how high temperatures affect the expression of the main genes regulating flower formation and how to improve crop management in these conditions.