Development of peach flower buds under low winter chilling conditions

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

Heritability of peach tree resistance to bacterial leaf spot.

The objective of this work was to evaluate the broad-sense heritability reaction to bacterial leaf spot (Xanthomonas arboricola pv. pruni), in peach tree populations obtained from directed crosses. Disease severity and defoliation of the genotypes were evaluated in field conditions, with posterior measurement of the healthy leaf area duration (HAD). The observed average heritability (0.51) indicates that the use of the evaluated genitors can be effective for the development of cultivars with higher resistance to the disease.Notas Científicas. Título em português: Herdabilidade de resistência de pessegueiro à bacteriose foliar

Physiological and sensorial aspects of peach fruits cv. Chimarrita depending on the season and management of green pruning.

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Performance of clonal rootstocks for "BRS-Kampai" peach and own-rooted trees in a mild-winter region.

Abstract: The worldwide main peach-producing are adopting peach training systems with canopy size-controlling clonal rootstocks. However, most peach seedlings commercialised in Brazil are still on seed-propagated rootstocks, which are vigorous and heterogeneous. This study aimed to select rootstocks which induce desirable characteristics of fruit quality, yield efficiency, size control, adaptability and stability in the ‘BRS-Kampai’ grown in subtropical regions with mild winters. We used adaptability and stability methodology and multivariate selection index to determine yield components and fruit quality. The experiment was conducted in five cycles. The treatments consisted of ‘BRS-Kampai’ grafted onto 17 clonal rootstocks of Prunus spp. and own-rooted trees. The evaluated variables were yield per tree, yield per area, fruit mass, fruit diameter, fruit firmness, soluble solids content, titratable acidity, canopy volume and yield efficiency. The rootstocks ‘Ishtara®’, ‘Genovesa’, ‘Santa Rosa’ and ‘Cadaman’ always induced low yield and low fruit quality when used as clonal rootstocks for the ‘BRS-Kampai’ and showed no potential for use as rootstocks in subtropical humid regions with mild winters. The ‘BRS-Kampai’ own-rooted peach trees or those grafted onto ‘Flordaguard’, ‘Okinawa’ are alternatives for peach cultivation under the edaphoclimatic conditions of Pato Branco-PR, although the training and pruning systems must be adjusted due to high vigour. The clonal rootstocks ‘Tsukuba-3’ and ‘Tsukuba-2’ induced the highest production performance in the canopy cultivar BRS-Kampai, combining fruit quality, yield with higher stability, and yield efficiency making them the most suitable ones among the studied rootstocks. Resumo: Sistemas de condução de pessegueiros com porta-enxertos clonais que reduzem vigor da copa são os mais adotados mundialmente. Entretanto, no Brasil ainda se utiliza porta-enxertos propagados por sementes, que são vigorosos e heterogêneos. Este trabalho teve como objetivo selecionar porta-enxertos que induzam qualidade de frutos, eficiência produtiva, controle de vigor, adaptabilidade e estabilidade em ‘BRS-Kampai’ cultivada em regiões subtropicais com invernos amenos. Foram utilizadas metodologias de adaptabilidade e estabilidade e índice de seleção multivariada para determinar os componentes de produção e qualidade dos frutos. O experimento foi conduzido em cinco ciclos. Os tratamentos consistiram de pessegueiro ‘BRS-Kampai’ autoenraizado ou enxertado em 17 porta-enxertos clonais de Prunus spp. As variáveis avaliadas foram produção por planta, produtividade por área, massa de frutos, diâmetro e firmeza de frutos, teor de sólidos solúveis, acidez titulável, volume de copa e eficiência produtiva. Em regiões subtropicais com invernos ‘Ishtara®’, ‘Genovesa’, ‘Santa Rosa’ e ‘Cadaman’ induziram baixa produtividade e baixa qualidade de frutos na ‘BRS-Kampai’ e não apresentam potencial para uso como porta-enxertos. ‘BRS-Kampai’ autoenraizadas ou enxertadas em ‘Flordaguard’ e ‘Okinawa’ são alternativas para o cultivo do pessegueiro, embora os sistemas de condução e poda devam ser ajustados devido ao alto vigor. Os porta-enxertos clonais ‘Tsukuba-3’ e ‘Tsukuba-2’ induziram o maior desempenho produtivo na ‘BRS-Kampai’, aliando qualidade de frutos, produtividade com maior estabilidade e eficiência produtiva tornando-os os mais indicados entre os porta-enxertos estudados.Título em português: Desempenho de porta-enxertos clonais para pessegueiro 'BRS-Kampai'e autoenraizado em região de inverno ameno

Chilling requirement for seed germination and phenological observations on peach cultivars

In subtropical climate areas, the models and methods proposed to evaluate the chilling requirement of temperate fruit crops often do not provide satisfactory results, thus calling for the development of alternative techniques. The aim of this study was to evaluate the correlations between some phonological traits and chilling requirement for seed germination of 18 peach cultivars and one nectarine cultivar. Two experiments were installed separately for the correlation studies. In experiment 1, the phenological traits were observed in the field, while in experiment 2, the chilling requirement for 50 and 100% seed germination of each cultivar was assessed. The number of days for beginning of bloom (r = 0.70**, 0.61**) and full bloom (r = 0.72**, 0.76**) were both significantly correlated with the number of chilling units for 50% and 100% germination of seeds. The number of days for beginning of budding and dormancy break were both significantly correlated with the number of chilling units for 50% and 100% germination (r = 0.48*, 0.50*, respectively). However, the same significant effect for these phenological traits was not found between chilling units and 50% germination of seeds, as well as between chilling units and harvest dates