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Abstract: Rosy apple aphid (RAA), Dysaphis plantaginea Passerini (Homoptera: Aphididae), is a major apple pest that is normally controlled by insecticide sprays. The use of tolerant cultivars to reduce damage of this aphid would contribute to a non-chemical crop protection. This study evaluated the susceptibility of nine scab-resistant apple cultivars (‘Dayton’, ‘Freedom’, ‘Galarina’, ‘GoldRush’, ‘Jonafree’, ‘Liberty’, ‘Priscilla’, ‘Redfree’ and ‘Williams’ Pride’) to RAA. Greenhouse trials and field observations were conducted for 2 years. Significant differences were observed among cultivars in aphid abundance and damage level 21 days after an infestation in the greenhouse. ‘GoldRush’ and ‘Galarina’ did not show typical leaf-rolls induced by RAA and were considered tolerant to this aphid species. Some cultivars showed low susceptibility while the cultivars ‘Jonafree’ and ‘Redfree’ turned out to be highly susceptible. Aphid abundance and damage levels were positively correlated. Field surveys confirmed greenhouse results. Growing cultivars resistant to scab and tolerant or only slightly susceptible to RAA would reduce pesticide use and increase opportunities for sustainable apple production. [Copyright &y& Elsevier]

[Display omitted] • Chill requirements (CR) of apple cultivars ranged from 59 to 90 Chill Portions (CP). • Decreasing winter chill is projected in northwestern Spain under all scenarios. • Chill-related problems are likely to arise on farms growing high-chill cultivars. • Cultivars with low CR are expected to be viable under pessimistic climate scenarios. • Adaptation strategies are feasible since 72 CP are expected for the worst scenario. Winter chill is expected to decrease in many mild-winter regions under future climatic conditions. Reliable estimates of the chill requirements (CR) of fruit trees are essential for assessing the current suitability of cultivars and potential climate change impacts on fruit production. We determined chill and heat requirements of ten apple cultivars in northwestern Spain using a bud-forcing method. CR ranged from 59 ('Granny Smith') to 90 ('Regona') Chill Portions (CP) according to the Dynamic Model. These results indicate that international dessert apple cultivars such as 'Elstar' and 'Granny Smith' have clearly lower CR than the studied local cultivars. The agro-climatic needs of the traditional apple cultivars are aligned with the historical climate conditions in the region. To assess future apple cultivation in northwestern Spain, we evaluated winter chill availability over the course of the twenty-first century by applying an ensemble of future climate scenarios. Relative to the past, projected winter chill might decline by between 9 and 12 CP under an intermediate global warming scenario and by between 9 and 24 CP under a pessimistic scenario. Despite relatively minor changes, the viability of some local apple cultivars may be jeopardized by their high CR. Results suggest that even a moderate decline in future winter chill, relative to fairly high levels observed in the past, can threaten the economic sustainability of fruit tree orchards composed of high-chill genotypes. Strategies such as growing low- to moderate-chill cultivars may be critical for sustaining future apple production in the region. Our findings can help guide new breeding strategies aiming to develop climate-resilient cultivars adapted to future environmental conditions. [ABSTRACT FROM AUTHOR]

The phenolic profiles of apple cultivars from the SERIDA Asturian cider apple breeding program, including parents and progenies, were determined by ultrahigh-performance liquid chromatography-diode array detector-electrospray ionization-quadrupole time of flight/mass spectrometer in order to study the relationship between phenols and the resistance of apple tree cultivars to rosy apple aphid (RAA). A pattern recognition technique named partial least square discriminant analysis (PLS-DA) was used to classify apple cultivars based on resistance to RAA, resistant and susceptible, reaching scores with accuracy higher than 97% and 91% respectively. Hydroxycinnamic acids, particularly 4-caffeoylquinic acid (4-CQA) and 4- p -coumaroylquinic acid (4-pCoQA), were identified as the major player in RAA resistance by the PLS-DA model. Indeed, the isomerisation 5-CQA → 4-CQA is favoured in resistant cultivars, whereas the isomerisation 5-pCoQA → 4-pCoQA is favoured in susceptible cultivars. As a result, resistant cultivars accumulate higher amounts of 4-CQA than susceptible ones, and the opposite occurs for 4-pCoQA. Also, minor isomerisations of 5-CQA to 1-CQA or 3-CQA show opposite behaviour for resistant and susceptible cultivars. Cultivar resistance to RAA is concluded to be related with the phenylpropanoid pathway, the isomerisation reactions being the key metabolic reaction for a cultivar to be resistant or susceptible to RAA. [ABSTRACT FROM AUTHOR]

[Display omitted] • Nine mono-varietal industrial apple pomaces from cider production are characterized. • Apple pomaces are rich in essential minerals, polyphenols and fibers (i.e., pectin). • Ultrasound-assisted extraction produces high-purity pectin. • Pectin from Sol variety may have good gelling properties based on GalA levels. • Pectin from Per/Reg varieties may act as biofunctional ingredients (GalA/Rha ratio). Comprehensive chemical characterization of nine mono-varietal apple pomaces obtained from the production of ciders with PDO is described. They were rich in essential minerals, fibers (35–52.9 %), and polyphenols. High levels in GalA (11.8–21.6 %), revealed the suitability of these apple pomaces as efficient sources of pectins. Extracted pectins showed high variability in monomer composition, with degrees of methylesterification, strongly associated with pectins functional properties, ranging from 58 to 88 %. For a subset of apple pomace varieties, pectin extraction was accomplished by conventional acid heat treatment or ultrasound. Despite ultrasound-assisted extraction did not improve pectin yield, it minimized levels of "non-pectin" components as revealed by the low content of Glc/Man, leading to the obtainment of high-purity pectin. Our work highlights the key role played by the selection of the apple variety to streamline the potential food applications (gelling/thickening agents or prebiotics) of the extracted pectins that largely depend on their structural features. [ABSTRACT FROM AUTHOR]

• A temperature rise of 0.30 °C/decade did not imply a reduction in winter chill. • Local apple cultivars showed a weak phenological response to warming. • Resilience to warming winters appears to vary across cultivars. • Partial Least Squares analysis indicated similar chill needs across cultivars. • Temperatures during the chilling and the forcing phases are equally important. In a global warming context, analyses of historic temperature records are essential to understand the potential impacts of climate change on spring phenology. To estimate flowering trends over recent decades, we analyzed long-term temperature and phenology records of eleven local apple cultivars in Asturias (northwestern Spain) in a temperate oceanic climate. Our results show that, over a period of 30 years, bloom dates of the local cultivars have experienced relatively minor changes, considering that temperatures increased strongly since 1978, by 0.30 °C per decade. An explanation for this weak phenological response to warming may be that these temperature changes only had a small effect on overall chill accumulation, but possibly delayed the onset date of endodormancy, which may have counteracted phenology-advancing effects of warming in spring. At present, chill accumulation in this area is high, at an average of 96 Chill Portions from November to March, which indicates that chill is not currently a limiting factor for the quality of flowering and fruiting in the study area. We used Partial Least Squares (PLS) regression to delineate an effective chilling period between November 12th and February 9th and effective heat accumulation between March 15th and May 4th. While these periods appear plausible, we noticed that this approach was unable to identify well-known differences in chilling requirements among many of the cultivars, with similar chill needs determined for many of them. This observation may be explained by inaccurate expectations about cultivars' climatic needs, by inaccuracy of the chill (and possibly heat) model or, most concerning, by inability of the PLS approach to correctly identify the chilling periods of apple cultivars in this region. Bloom dates were similarly responsive to mean temperature during the chill and the heat accumulation phases, indicating that both processes need to be considered when predicting future phenology. [ABSTRACT FROM AUTHOR]