‘Rafel’ and ‘Belgida’ are mid- to early-ripening apricot cultivars (Prunus armeniaca L.) with good yield, excellent fruit quality, self-compatibility, and resistance to Sharka, a disease caused by the Plum pox virus, a serious limiting factor for apricot production in Europe. Their fruits have excellent organoleptic characteristics and are larger than the traditional Valencian cultivars. ‘Rafel’ and ‘Belgida’ are very well adapted to the climatic conditions of the Valencia and Murcia areas.
Origin
‘Rafel’ and ‘Belgida’ both resulted from a cross made in 1993 at Valencia, Spain, between the North American cultivar Goldrich and the Spanish cultivar of unknown origin, Ginesta (Fig. 1). This cross was made with the objective of obtaining cultivars resistant to Sharka, early- to midripening and self-compatible with good fruit quality and better size than traditional Valencian cultivars. ‘Goldrich’ was selected as the female parent as a result of its resistance to Sharka, its large fruit size, and its adaptability to mild winters. ‘Ginesta’ was used as the male parent because it ripens early in the season, has excellent fruit quality, and is self-compatible.
Pedigree of ‘Rafel’ and ‘Belgida’ apricots.
Citation: HortScience horts 45, 12; 10.21273/HORTSCI.45.12.1904
Description
Tree characteristics
Tree description.
‘Rafel’ and ‘Belgida’ were selected as seedlings in 1996. They were subsequently grafted on apricot rootstock and located in experimental plots in different climatic zones in the Valencia and Murcia regions (four trees per variety). They were planted according to commercial distances (5 × 4 m) and received standard cultural practices. Data presented in Table 1 were collected during four growing seasons on trees 4 years old at the IVIA (Valencia, Spain) experimental plot (lat. 39°34′ N, long. 0°24′ W, altitude 55 m). Trees of ‘Rafel’ were vigorous, have a spreading habit, and vegetative bud break occurs in mid-March. Mean yield from 4 cropping years was 67 kg/tree. ‘Belgida’ trees were also vigorous, have a spreading habit, and vegetative bud break occurs the third week of March. Mean yield from 4 cropping years was 98 kg/tree (Table 1).
Comparative analysis of tree and fruit characteristics of ‘Rafel’, ‘Belgida’, ‘Ginesta’, and ‘Goldrich’ under experimental conditions in IVIA, Valencia, Spain.
Plum pox virus resistance.
Sharka disease, caused by the Plum pox virus (PPV), is a serious limiting factor for temperate fruit production in those areas where the virus has spread (Kölber, 2001). During the 1980s and 1990s, apricot production was seriously affected by PPV in Spain, France, and Italy (Roy and Smith, 1994). All native apricot cultivars are susceptible to PPV and removal of infected trees was ineffective in eradicating the disease (Llácer and Cambra, 1998), whereas several cultivars from North America such as ‘Goldrich’, ‘Sunglo’, ‘Orange Red’, and ‘Stark Early Orange’ show resistance to PPV and are used as parents in breeding programs aimed at introducing resistance to PPV (Egea et al., 1999). In the case of ‘Rafel’ and ‘Belgida’, ‘Goldrich’ was used as the donor of resistance looking for better adaptability to warm winters. Evaluation of PPV resistance was performed in controlled greenhouse conditions following the methodology described by Moustafa et al. (2001). Seedlings grafted on peach GF-305 infected with PPV went through two cycles of cold treatment after inoculation to mimic two normal season cycles to speed up the selection followed by enzyme-linked immunosorbent analysis and polymerase chain reaction analysis. No symptoms were observed on either cultivar and presence of the virus was not detected by either analysis method. Additionally, three trees per accession were planted in a production area heavily infected with PPV. These trees were surrounded by infected, susceptible cultivars and inoculated by chip budding in the open field with the Dideron-type PPV isolate (López-Moya et al., 2000). No symptoms were observed 3 years after inoculation. PPV symptoms were observed in the neighboring susceptible trees. Results showed that ‘Rafel’ and ‘Belgida’ are resistant to Dideron-type PPV isolates.
Time of bloom and floral compatibility.
Full bloom of ‘Rafel’ occurred at a similar time as ‘Ginesta’, in the last week of February, ≈1 month ahead of ‘Goldrich’ (Table 1). ‘Rafel’ had high flowering intensity, mainly localized (85%) on fruiting spurs of 2- or more year-old branches. Flower bud drop was low and the flowers were self-compatible. On the other hand, full bloom of ‘Belgida’ occurred in the second week of March, which is an average flowering date compared with its parents (Table 1). ‘Belgida’ also had high flowering intensity, mainly localized (90%) on fruiting spurs of 2 or more year-old branches. Bud drop was medium–low and flowers were self-compatible. Self-compatibility was demonstrated in the field by enclosing whole trees in insect-proof screening and in the laboratory using molecular markers from RNAs developed by Vilanova et al. (2005).
Fruit characteristics
Maturation time.
‘Rafel’ and ‘Belgida’ are mid- to early-ripening cultivars in comparison with traditional Spanish apricot cultivars. In our experimental conditions, the ripening date average for ‘Rafel’ and ‘Belgida’ was the last week of May for ‘Rafel’ and 5 d later for ‘Belgida’ (Table 1). ‘Rafel’ and ‘Belgida’ fruits mature moderately staggered within the tree canopy and uniformly within individual fruit. Fruit cracking was low in both cultivars. Fruits of ‘Rafel’ are produced on fruiting spurs (100%) and mainly (85%) on fruiting spurs for ‘Belgida’.
Fruit size, firmness, and color.
Fruit characterizations of ‘Rafel’ and ‘Belgida’ were measured from a sample of 25 fruit from each cultivar at the stage of physiological maturity. Fruits of ‘Rafel’ were round with a slight asymmetry, a slightly sunken suture, and a smooth pubescent surface (Fig. 2). The fruit surface ground color was yellow with a solid red blush of medium intensity covering ≈35% of the surface. The flesh was yellow to light orange. The pit was free. ‘Rafel’ fruits averaged 48 mm in diameter (cheek to cheek), 58 g weight, with a firmness of 1.8 kg·cm−2. Fruits of ‘Belgida’ were rounded–ovalate with a slight asymmetry, a medium sunken of suture, and a smooth pubescent surface. The surface of the fruit had a light orange ground color with solid red blush covering ≈20% of the surface. The flesh was orange and clingstone. ‘Belgida’ fruits averaged 48.5 mm in diameter, 69 g weight, with a firmness of 4.6 kg·cm−2.
‘Rafel’ (left) and ‘Belgida’ (right) apricot fruits. Bar in centimeters.
Citation: HortScience horts 45, 12; 10.21273/HORTSCI.45.12.1904
Organoleptic characteristics.
At the physiological maturity stage, ‘Rafel’ and ‘Belgida’ fruits showed soluble solids concentration of 14.5 and 14%, respectively, and titratable acidity of 29.0 and 27.0 g·L−1 malic acid, respectively (Table 1). ‘Rafel’ and ‘Belgida’ fruits had an excellent taste, juiciness, and typical apricot aroma.
Availability
The Rafel and Belgida cultivars are protected by the Spanish Office for Varietal Protection with the registration numbers 2001/4347 and 2007/4737, respectively. Virus-tested plants are available from authorized nurseries in Spain registered at http://www.agroalimed.es. The plants are tested and free of the following viruses: PPV, Prune dwarf ilarvirus, Prunus necrotic ringspot ilarvirus, Apple chlorotic leafspot closterovirus, and Apple mosaic ilarvirus.
Literature Cited
Egea, J., Burgos, L., Martínez-Gómez, P. & Dicenta, F. 1999 Apricot breeding for sharka resistance at CEBAS-CESIC, Murcia (Spain) Acta Hort. 121 207 210
Kölber, M. 2001 Workshop on Plum pox Acta Hort. 550 249 255
Llácer, G. & Cambra, M. 1998 Thirteen years of sharka disease in Valencia, Spain Acta Hort. 472 379 384
López-Moya, J.J., Fernández-Férnandez, M.R., Cambra, M. & García, J.A. 2000 Biotechnological aspects of Plum pox virus J. Biotechnol. 76 121 136
Moustafa, T.A., Badenes, M.L., Martínez-Calvo, J. & Llácer, G. 2001 Determination of resístanse to sharka (Plum pox) in apricot Sci. Hort. 91 59 70
Roy, A.S. & Smith, I.M. 1994 Plum pox situation in Europe EPPO Bulletin 24 515 524
Vilanova, S., Romero, C., Burgos, L., Llácer, G. & Badenes, M.L. 2005 Identification of self-(in)compatibility alleles in apricot by PCR and sequence analysis J. Amer. Soc. Hort. Sci. 130 893 898
