plantations designed to be mechanically Breeding Oil and Table Olives for Mechanical harvested. Therefore, only a few tradi- Harvesting in Spain tional cultivars are currently planted in the new orchards. The need for new specific cultivars for these new planta- Luis Rallo1 tions has stimulated the development of breeding programs in various countries. This review summarizes the develop- ADDITIONAL KEY WORDS. mechanization, Olea europaea, olive breeding, ‘Sikitita’ ment of the current olive breeding pro- SUMMARY. The olive (Olea europaea) and table olive industries worldwide are almost grams in Spain. entirely supported by low-density rain-fed orchards planted with local cultivars empirically selected by farmers for centuries. New early and high-bearing plantation Genetic resources systems adapted to mechanical harvesting have been designed and developed during Exploration, conservation, evalua- the past 50 years. Only certain traditional cultivars are well suited for these new olive tion, and sustainable use of genetic plantations. The new orchards therefore require new cultivars. A long-term effort on the exploration, conservation, and sustainable use of olive genetic resources resources represent a first step in breed- starting in Spain in 1970 has been followed by breeding programs developed since ing. Systematic exploration of cultivars the early 1990s by the University of Cordoba, the University of Seville, and the and centennial olives (i.e., wild and Andalusia Institute for Agricultural, Food and Fisheries Research. We are trying to cultivated olives over 100 years old) use crossbreeding to obtain new early bearing cultivars adapted to mechanically has been developed in Spain since 1970 harvested orchards. Objectives related to shortening the juvenile period (JP) and (Dı´ez et al., 2011). More than 300 developing early tests of selection, early bearing, high cropping, resistance to chief different cultivars (Barranco et al., diseases (particularly verticillium wilt caused by Verticillium dahliae), industrial 2005; Mun˜oz-Diez, 2008) have been suitability, high oil content, diversity of olive oil composition for oil cultivars, and found and have been progressively in- fruit size and quality for table olive are being pursued. Specific criteria for the cluded in the Olive World Germplasm adaptation of oil olive and table olive cultivars to mechanical harvesting, such as low-vigor trees with a compact growth habit, the force needed for fruit removal, Bank (OWGB) in Cordoba, Spain. natural fruit abscission, resistance to bruising, and extending the harvest time in In 1994, the International Olive cultivars showing homogeneous ripening are evaluated in the progenies. To date, Oil Council promoted a network of more than 19,000 seedlings have been initially evaluated, 481 preselections are on national banks of germplasm. This net- intermediate field trials, and 31 advanced selections are being established in work currently includes 968 accessions a network of field trials. A new protected cultivar Sikitita (Chiquitita in the United of supposed autochthonous cultivars States), selected for very-high-density narrow hedgerows, was released in 2008. from 17 countries. It also includes two Recently, a first project on olive genomics is heralding the use of marker-assisted international repositories, the OWGB selection in the midterm phase of development. Cultivars adapted to the new in Cordoba, Spain and another in Mar- mechanical harvest systems will be progressively released in the future. rakech, Morocco. A third is projected in Turkey (Essid, 2010). The joint use of raditionally, olives have been and mechanical harvesting became different molecular DNA markers, cultivated in rain-fed farms with compulsory. Since then, these planta- diversity array technology and simple Tdensities of 17–300 trees/ha tions have begun to be replaced by sequence repeated, and morphologi- depending on rainfall. Locally selected high-density mechanically harvested or- cal descriptors (Atienza et al., 2013; cultivars were propagated and planted chards. Rain-fed intensive (150–200 Trujillo et al., 2014) confirmed most by farmers, and trees were trained and trees/ha) and irrigated orchards (250– of the previously identified cultivars by pruned according to many diverse em- 400 trees/ha), high-density irrigated morphological markers (Barranco et al., pirical methods to enhance harvesting orchards with wide hedgerows (400– 2005) and have shown a high capacity by hand or by poling. These plantations 800 trees/ha), and superintensive or- to identify cultivars and determine syn- were low yielding, late bearing, and chards [i.e., very-high-density rain-fed onyms, homonyms, and erroneous cul- long lasting. Certain traditional planta- orchards with narrow hedgerows (800– tivar names in the OWGB in Cordoba. tions were irrigated, resulting in marked 1000 trees/ha) and very-high-density These problems commonly arise in increases in yield. These irrigated or- irrigated orchards with narrow hedge- relationship to the accessions in most chards have been planted with 70–100 rows (>1500 trees/ha)] are increasingly olive germplasm collections (Bartolini trees/ha. After World War II, rural planted for harvest by various mechan- et al., 2005). migration increased production costs, ical systems (Rallo et al., 2013). Pre- The evaluation of agronomic and viously, these new orchards have oleotechnic traits in two germplasm Departamento de Agronomı´a, Campus de Rabanales, depended on traditional cultivars that banks in Spain [Cordoba and Reus Universidad de Co´rdoba, 14014 Co´rdoba, Spain were locally selected. However, most (Rallo et al., 2005)] has shown high This paper was part of the colloquium ‘‘Strategy for of these cultivars display traits that phenotypic variability for all traits eval- Developing Mechanical Harvesting of Horticultural would be undesirable for high-density uated and provides useful information Crops: Simultaneous Short-, Medium-, and Long- term Strategies’’ held 24 July 2013 at the ASHS Annual Conference, Palm Desert, California, and sponsored by the Production and Harvest Mechani- zation (MECH) Working Group. Units The author is in debt with Diego Cabello, Pilar Rallo, To convert U.S. to SI, To convert SI to U.S., and Carlos Trapero for their support in preparing and multiply by U.S. unit SI unit multiply by editing this article. 0.4047 acre(s) ha 2.4711 1Corresponding author. E-mail: [email protected]. 0.3048 ft m 3.2808
• June 2014 24(3) 295 COLLOQUIUM for identifying parents for use in the diameter of the seedlings during their selected seedlings (preselections) for breeding programs. first period of growth are good in- a preliminary evaluation of major ag- dicators of their potential for early ronomic traits such as crop production Crossbreeding programs flowering (De la Rosa et al., 2006). and vigor that require replication of in Spain The use of these indicators allowed the preselections. The best ones (ad- a 40% reduction of the smaller plants, vanced selections) are finally included There are few olive breeding which had a very low potential for in a network of field trials for eval- programs worldwide. In Spain, the first flowering, by the end of their growing uating the genotype-by-environment breeding program was initiated by period in the greenhouse (P. Rallo interaction in the expected areas of 1990. Most of the programs were et al., 2008a). The relationship among distribution for these potential new designed to obtain cultivars for oil and the vigor of the plants in the year cultivars. a few for table olives by crossbreeding. previous to the first flowering, the A first tentative protocol for the To date, programs from only three percentage of flowered plants, and evaluation of olive progenies in our countries, Israel, Italy, and Spain, have the amount of inflorescences and fruit program is presented in Fig. 1. yielded 14 new releases (De la Rosa and in the seedlings during the first year of EARLYANDHIGHCROPYIELD. Leo´n, 2009). flowering appears to represent a gen- New mechanized olive plantations eral pattern (Moral et al., 2013). imply high investment, particularly Shortening the JP in irrigated orchards. Therefore, they The length of the JP has been the Agronomic evaluation and should be able to ensure early bearing principal obstacle hampering the im- objectives and high cropping over the whole life provement of fruit trees by cross- THE PROCESS OF EVALUATION. of the orchard, as early and continu- breeding. Fruit evaluation in the There are three main stages for the ous return becomes necessary for the progeny is initiated when the JP ends. evaluation of the individuals from any investment to be profitable. Forcing the growth of the seedlings cross progeny. Many nonreplicated Records of the number of flow- and the identification of early criteria seedlings per cross are initially evalu- ering trees and inflorescences per tree for selecting early bearing seedlings ated according to the main objectives from the second to the fourth year are known. Early research efforts of the program. The second stage after planting the seedlings in the resulted in very consistent methods includes field trials with the above open field has proven to be a useful for fast, uniform, and high seed ger- mination. Procedures to force growth of seedlings under continuous light- ing and fertigation in the greenhouse were also beneficial (Santos-Antunes et al., 2005). This protocol allowed the trees to flower in the following proportions over time: 4% to 22% at 26 to 28 months after the sowing of the seeds, 47% to 65% at 38 to 40 months after sowing, and 58 to 85% at 50 to 52 months after sowing. Flowering precocity varied among the progenies corresponding to the parents (‘Arbequina’ > ‘Picual’ > ‘Frantoio’). More recent results have indi- cated that this protocol can be further improved. Moreno-Alias et al., (2010) have shown that training the canopy between 1.00 and 1.30 m high does not delay the time of the first flowering relative to that obtained with the canopy height of 1.60 m used in the first protocol. These results represent an opportunity for improving the forcing protocol, advancing the first flowering, and simplifying the field management of the progeny, as both the trunk and the canopy are easily Fig. 1. Breeding scheme for olive programs in Spain. Initial individual seedlings were evaluated according to the main criteria of selection. The seedlings selected, managed. preselections, were then evaluated for main agronomic and oleotechnic traits in Early selection tests have success- intermediate field trials with few replications. Advanced selections were evaluated fully shortened the JP and eliminated for many agronomic and oleotechnic traits in comparative field trials in one or more late-flowering seedlings early in their locations. In the later case, the interaction genotype by environment (G · E) was development. The height and the evaluated (Rallo et al., 2011a).
296 • June 2014 24(3) measure for selecting seedlings prog- term ’’blistering defect’’ refers to the cultivars, Picual and Arbequina, were enies and evaluating progenitors for breakage of the olive skin that eventu- also moderately resistant (Moral early bearing (Leo´n et al., 2007; ally occurs during treatment with lye. et al., 2005). Moral et al., 2013; Santos-Antunes Resistance/susceptibility to fruit bruis- For anthracnose, most of the et al., 2005). ing and the suitability for specific pro- major Spanish cultivars evaluated High oil content of olives is also cessing methods need to be determined were susceptible or highly suscepti- critical for oil cultivars. A higher oil (Jime´nez, 2009; Jime´nez et al., 2011). ble. Only ‘Empeltre’ and ‘Picual’ content than that of standard high Over-the-row harvesters have showed a degree of resistance, with oil-yielding cultivars such as Picual, ensured full fruit removal and olive ‘Arbequina’ highly susceptible and Frantoio, or Arbequina has proven to oil quality (Lavee, 2010; Rallo et al., ‘Frantoio’ resistant (Moral and Trapero, be an efficient criterion for selection 2013). However, olive bruising and 2009). Several of the preselections based on analytical data provided by blistering are reduced, not elimi- for early bearing and high oil content magnetic nuclear resonance or near- nated, in green table olives (Jime´nez, from the crosses among ‘Arbequina’, infrared spectroscopy and on samples 2012). Resistance to these forms of ‘Frantoio’, and ‘Picual’ were signifi- representing only 2 years (Leo´n et al., damage continues to be an objective cantly more resistant than ‘Arbequina’, 2004).The extractability of oil (i.e., in the breeding of table olives. particularly in the case of genotypes the relationship between the percent- Although reductions in tree size from the cross between ‘Frantoio’ age of oil extracted by a standard in- has been proposed to increase harvest and ‘Picual’ (Moral et al., 2006). dustrial process and the analyzed oil efficiency in trunk shaker systems, None of the preselections from content) is later evaluated in field which implies a tendency to shorten the crosses among Arbequina’, ‘Fran- trials with advanced selections. orchard lifespan (Ferguson, 2006), toio’, and ‘Picual’ were resistant to ADAPTATION TO MECHANICAL a small and compact growth habit cercosporiose. This lack of resistance HARVEST. New high-density olive becomes a critical objective in the is most likely due to the susceptibility plantation systems are mechanically use of modified grape (Vitis sp.) of the three genitors to the pathogen harvested with various types of equip- straddle harvesters for collection in (Moral et al., 2005). New resistant ment (Rallo et al., 2013). These pro- narrow hedgerow plantation. In this genitors, such as ‘Koroneiki’, are be- cedures require specific cultivar traits context, preliminary results have ing used in new crosses and the re- to ensure harvesting efficiency and shown the influence of the genitors sultant progenies are under evaluation. the quality of either olive oil or table on the vigor and growth habit of the A two-step protocol for evaluating olives. seedlings at the end of the initial step cultivars and seedling genotypes for Inertia trunk shakers combined of evaluation in the field (Rallo et al., resistance to verticillium wilt is currently with complementary catching frames, 2011a). on course in a controlled environ- inverted-umbrella and ‘‘side-by-side’’ A review on the works on genetic mentandinhighlyinfestedfieldplots designs, are generally used in inten- resources and breeding in olive with (Trapero et al., 2011, 2013a). The first sive plantation systems (Rallo et al., reference to quality has been pub- step is the screening of 40-day-old olive 2013). Traits such as fruit weight lished (Rallo et al., 2011b). seedlings via root-dipping inoculation (FW), fruit removal force (FRF), and R ESISTANCE TO FUNGAL with a highly virulent V. dahliae isolate the FRF/FW ratio, natural fruit ab- DISEASES. The new mechanized and (V117) in a controlled environment. scission before harvesting and homo- irrigated high-density plantation sys- This screening program discriminates geneous fruit ripening for the selected tems have been related to a higher between resistant and susceptible seed- seedlings once the fruit have reached incidence of certain diseases than that lings in a short period of time (Trapero their oil content threshold are desir- occurring in standard rain-fed or- et al., 2013a). This method has allowed ableforcultivarsuitabilityinor- chards. These included airborne defo- the screening of more than 8000 seed- chards harvested with trunk shakers liating fungal diseases and verticillium lings, of which 600 were resistant. (Humanes-Guille´n, 1976). A high level wilt of olives (Rallo et al., 2013). The second step is a field evaluation in of variability of these traits among Tests for evaluating resistance to pea- plots infested with the highly virulent cultivars has been reported in Spain cock spot (Fusicladium oleaginum), V. dahliae isolate. Eleven cultivars, in- (Kouraba et al., 2004) and among cercosporiosis (Pseudocercospora cla- cluding resistant and susceptible ones seedlings from breeding progenies that dosporioides), and anthracnose (Colle- (Trapero et al., 2013b), have been further increase the variability of the totrichum sp.), the three principal tested in these field trials with several parents (De la Rosa et al., 2008). airborne defoliating diseases, in culti- replications. Almost all trees of ‘Bodo- Damage to the skin, flesh of the vars of the OWGB in Cordoba and in quera’, ‘Cornicabra’, ‘Manzanilla de olive fruit, or both are determining progenies and preselections of our Sevilla’, and ‘Picual’ were killed. In factors that reduce the quality of the program have shown high variability contrast, ‘Empeltre’, ‘Changlot Real’, processed fruit in table olives. Several among descendants from the same and‘Frantoio’showedahighlevel types of damage have been described cross. For peacock spot, with resistant of disease resistance (Trapero et al., according to the origin of the damage cultivars such as Frantoio and Lechı´n 2013b) after 20 to 22 months of (e.g., mussel-scale, hail-damage, wrin- de Sevilla used as parents, the proge- planting. Currently, this protocol of kled olive).Fruitbruising andblistering nies showed a high percentage of field evaluation is in progress for the are of special relevance. Bruises appear highly resistant or resistant seedlings, seedlings selected in the previous dip in the fruit as a result of physical impacts although several preselections for inoculation test (C. Trapero, personal during harvesting and subsequent early bearing and high oil content communication). In summary, this postharvest manipulation, whereas the from crosses between two susceptible protocol may, after a short time (2 to
• June 2014 24(3) 297 COLLOQUIUM
3 years), yield preselections resistant to (Medina et al., 2012; P. Rallo et al., released in 2008 (L. Rallo et al., verticillium wilt and produce advances 2008b). Finally, protocols to evaluate 2008). The first commercial orchards in their agronomic preliminary evalu- several other interesting traits, such of this cultivar were planted in 2009. ation, thus reducing the time required as resistance/susceptibility to fruit They produced their first full crop in for the initial and the intermediate bruising or suitability for specific pro- 2012–13 (Fig. 2). The traits of this evaluation stages (Fig. 1). cessing methods, are being established new cultivar are presented on an QUALITY OF OIL AND TABLE (Jime´nez, 2009, 2012; Jime´nez et al., updated web page (Pomologı´a OLIVES. Fatty acids (Leo´n et al., 2011). Sociedad Limitada, 2013) with avail- 2004, 2008) and phenolic profiles able and useful information for the (El Riachy et al., 2012a, 2012b) have New materials scientific community and for the been evaluated in progenies and ad- Current state olive industry. vanced selections from various crosses The current state of the seedlings among ‘Arbequina’, ‘Frantoio’, and evaluated and in evaluation (Table 1) The future ‘Picual’. The composition of both summarizes the advances achieved by The changes occurring in olive fatty acid and phenolic compounds the breeding programs. All breeding plantations over the past 50 years will differs among these progenies and programs share common objectives certainly continue in the future. The selections. The following common (high and early crops, high-density best-suited cultivars for these new conclusions have been obtained for plantations, and mechanical harvest- orchards, including cultivars from both oil components: 1) any cross ing). Oil content is essential for oil Spain and several from abroad, had yields a higher range of variability cultivars, and the fruit size and shape been planted by the mid-1980s as the for any compound than the parents, and the quality of the processed olives nursery industry developed. either in progenies or advanced selec- are essential for table cultivars. Resis- The continuous efforts con- tions and 2) there is a highly signifi- tance to V. dahliae is the first criterion ducted in Spain since the 1970s have cant correlation among the values of for selection in a new program. The allowed cultivars to be catalogued and any individual in different stages of current data indicate the potential of to be conserved in germplasm banks, evaluation (initial progeny and ad- these breeding programs. with true-to-type accessions identi- vanced selections). We are currently propagating fied with morphological and molecu- In contrast, the evaluation of eight advanced selections for narrow lar markers. Agronomic evaluation in these compounds has shown the fol- hedgerow orchards to develop an ex- germplasm banks and in field trials lowing differences: 1) selection for perimental network in various coun- had been initiated by the mid-1970s. fatty acid composition can be per- tries according to a public–private The new olive breeding programs led formed efficiently by considering only agreement for collaboration. to a continuous process of phenotyp- a single year of evaluation at the ing in germplasm banks, progenies, seedling stage, 2) there are clear dif- ‘Sikitita’ and new selections. The recent pro- ferences between years in the compo- A new cultivar adapted to high- jects in olive genomics in various sition of the phenolic compounds, density hedgerow orchards has been countries will certainly increase the and 3) sampling at early fruit harvest selected and protected; it was then current knowledge of olive genetics is recommended for better compari- sons of phenolic compounds among seedlings due to the differential changes in the phenolic profile with Table 1. Approximate number of olive initial seedlings, preselections and advanced selections in the olive breeding programs of Spain. the progress of fruit ripening. These results suggest that new olive cultivars Advanced with a composition of fatty acids and Programs and objectivesz Initial (no.) Preselections (no.) selections (no.) phenolics that satisfies consumer and UCO-IFAPA (oil) 10,021 410 31 market demands could be obtained High and early crop through crossbreeding in the future. High-density plantations Similarly, in breeding for table Mechanical harvesting olives, fruit morphological traits such High oil content as fruit size and shape, stone size and US-IFAPA (table) shape, flesh:pit ratio, and flesh texture High and early crop have been evaluated (P. Rallo et al., High-density plantations 2008b, 2012). There is almost no Mechanical harvesting 1,800 80 information available on the compo- Fruit quality sition of the fruit in the progenies in UCO (oil and table) table olive breeding programs. Nev- Resistance to verticillium wilt ertheless, the influence of certain High and early crop compounds, such as polyphenols, tri- High-density plantations terpenic acids, and sugars, on the Mechanical harvesting quality of processed table olives is High oil content making breeders consider the possi- Fruit quality 8,000 600 ble inclusion of these traits in the zUCO = University of Cordoba, Cordoba, Spain; IFAPA = Andalusia Institute for Agricultural, Food and Fisheries evaluation of the progenies’ raw fruit Research, Seville, Spain; US = University of Seville, Seville, Spain.
298 • June 2014 24(3) El Riachy, M., F. Priego-Capote, L. Leo´n, Romero. 2012. New genotypes of table M. Dolores Luque-de-Castro, and L. olives: Profile of bioactive compounds. Rallo. 2012a. Virgin olive oil phenolic Intl. J. Food Sci. Technol. 47:2334– profile and variability in progenies from 2341. olive crosses. J. Sci. Food Agr. 92:2524– 2533. Moral, J., M. Alsalimiya, C. Mun˜oz-Diez, L. Leo´n, R. de la Rosa, and A. Trapero. El Riachy, M., F. Priego-Capote, L. Rallo, 2006. Evaluacio´n de preselecciones de M.D. Luque-de-Castro, and L. Leo´n. olivo por su resistencia a repilo y antrac- 2012b. Phenolic composition of virgin nosis. Actas de Horticultura 45:177–178. olive oils from cross breeding segregating ´ ´ populations. Eur. J. Lipid Sci. Technol. Moral, J., A. Avila, L.M. Lopez-Doncel, ´ 114:542–551. M. Alsalimiya, R. Oliveira, F. Gutierrez, N. Navarro, K. Bouhmidi, A. Benali, L.F. Fig. 2. High-density irrigated Essid, H. 2010. Olive genetic resources: A Roca, and A. Trapero. 2005. Resistencia hedgerow orchard of. ‘Sikitita’ olive planted at 4.0 · 1.5 m (13.12 · 4.92 ft) legacy of biodiversity. 28th Intl. Hort. a los repilos de distintas variedades de in Huelva, Spain. Flowering trees 29 Congr. Abstr. 1:307. (abstr.). olivo. Vida Rural 208:34–40. months after plantation. Ferguson, L. 2006. Trends in olive har- Moral, J., C.M. Dı´ez, L. Leo´n, R. de la vesting. Grasas y Aceites 57:9–15. Rosa, F. Santos-Antunes, D. Barranco, and L. Rallo. 2013. Female genitor effect ´ ´ and provide useful tools for breeding Humanes-Guillen, J. 1976. Recoleccion on the juvenile period of olive seedlings. in the midterm. The static picture of mecanizada de la aceituna, p. 293–316. Sci. Hort. 156:99–105. the cultivar map in all traditional In: J.M. Phillippe, J. Humanes-Guille´n, G. Piquer, and R. Te´llez-Molina. (eds.). Moral, J. and A. Trapero. 2009. Assessing olive-growing countries will be pro- Olivicultura moderna. FAO, INIA, and the susceptibility of olive cultivars to gressively replaced by newly bred Editorial Agrı´cola Espan˜ola, Madrid, anthracnose caused by Colletotrichum cultivars adapted to the new growing Spain. acutatum. Plant Dis. 93:1028–1036. areas and plantation systems. Jime´nez, R. 2009. Evaluacio´n de la apti- Moreno-Alias, I., H.F. Rapoport, L. tud de nuevos genotipos de olivo para su Leo´n, and R. De la Rosa. 2010. Olive Literature cited elaboracio´n como aceituna de mesa. Univ. seedling first-flowering position and man- ´ ´ Atienza, S.G., R. De la Rosa, M.C. Cadiz, Cadiz, Spain, MSc Diss. agement. Sci. Hort. 124:74–77. Domı´nguez-Garcı´a, A. Martı´n, A. Kilian, Jime´nez, R. 2012. Puesta a punto de Mun˜oz-Diez, C. 2008. Prospeccio´ n, and A. Belaj. 2013. Use of DArT markers me´todos de evaluacio´n de para´metros de diversidad gene´tica y conservacio´nde as a means of better management of the calidad de aceituna de mesa en un pro- ejemplares monumentales y poblaciones diversity of olive cultivars. Food Res. Intl. grama de mejora gene´tica. Univ. Seville, silvestres de olivo (Olea europaea L.). 54:2045–2053. Seville, Spain, PhD Diss. Univ. Cordoba, Cordoba, Spain, PhD Diss. Barranco, D. and I. Trujillo. 2005. Libro Jime´nez, R., P. Rallo, M.P. Sua´rez, A. I. Elaiografı´a Hispa´nica, p. 45–229. In: L. Morales-Sillero, L. Casanova, and H. Pomologı´a Sociedad Limitada. 2013. Rallo, D. Barranco, J.M. Caballero, C. Rapoport. 2011. Fruit bruising in table Sikitita. 25 Nov. 2013.
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