Olive is an andromonoecious species—that is, each olive tree forms perfect hermaphrodite flowers and staminate flowers, a result of pistil abortion. Olive also exhibits strong alternate bearing, with a high flowering season (“on year”) followed by a year of light flowering and yield (“off years”) due to inhibition of flower induction caused by excessive previous crop load. Olive orchards in Spain and other Mediterranean countries are commonly monovarietal, despite the partial self-incompatibility of most olive varieties. This is possible because open, wind pollination is often sufficient to obtain adequate yield, given the extraordinary varietal richness found in most traditional olive regions, where a mixture of varieties growing nearby is common (Pinillos and Cuevas, 2009). The situation is quite different in North America. In Mexico and the United States, olive orchards often are planted in isolated areas where the amount of cross-pollen available is limited (Shemer et al., 2014). This pollination deficit frequently reduces fruit set and yield in olives (Ayerza and Coates, 2004; Navarro-Ainza and López-Carvajal, 2013; Sibbett et al., 1992). Therefore, to ensure a high yield, orchard designs including pollinizers in the correct proportion and position are required in these nontraditional olive countries. Artificial pollination is also an alternative (Sibbett et al., 1992).
If a pollination design is required, the chosen pollinizer must meet certain requirements. It must be intercompatible with the main variety, bloom at the same time, and be regular (i.e., not an alternate bearer). On a secondary level, given its main function as pollen donor, it is also convenient to select high-yielding pollinizers of high commercial value and the same purpose (table or oil) with similar crop requirements and vigor (Cuevas et al., 2001).
‘Manzanillo’ is the most important table olive in the world (Rejano et al., 2010). Unfortunately, ‘Manzanillo’ yields are not always optimal. Contradictory results regarding its degree of compatibility can be found in the literature. Some authors have reported ‘Manzanillo’ to be highly self-incompatible (SI) (Androulakis and Loupassaki, 1990; Cuevas and Polito, 1997; Griggs et al., 1975), whereas other authors label it as only partially SI, not expressing complete rejection of self-pollen but preferring cross-pollen for fertilization and hence increasing fruit set and yield under cross pollination (Dimassi et al., 1999; Lavee et al., 2002; Wu et al., 2002).
To check ‘Manzanillo’ behavior and its pollination requirements in a nontraditional olive country, such as Mexico, we designed different pollination experiments with three main aims. First, to determine whether a pollination deficit exists in monovarietal Manzanillo orchards, establishing the level of self-incompatibility exhibited. Second, to compare ‘Manzanillo’ response to open-pollination in monovarietal vs. multivarietal orchards of this genotype. The third objective was to select a good pollinizer for ʻManzanilloʼ, comparing the performance of ‘Sevillano’ and ‘Barouni’ as pollen donors because these varieties are commonly used in Mexico and the United States for this purpose.
CuevasJ.Díaz-HermosoA.J.GaliánD.HuesoJ.J.PinillosV.PrietoM.SolaD.PolitoV.S.2001Response to cross-pollination and choice of pollinisers for the olive cultivars (Olea europaea L.) ‘Manzanilla de Sevilla’, ‘Hojiblanca’ and ‘Picual’Olivae852632
DimassiK.TheriosI.BalatsosA.1999The blooming period and self-fruitfulness in twelve Greek and three foreign olive cultivarsActa Hort.474275278
FarinelliD.PierantozziP.PaleseA.M.2012Pollenizer and cultivar influence seed number and fruit characteristics in Olea europaea LHortScience4714301437
Fernández-EscobarR.RalloL.1981Influencia de la polinización cruzada en el cuajado de frutos de cultivares de olivo (Olea europaea L.)Inf. Téc. Econ. Agrar.455158
FichtnerE.J.2012Olive bloom and pollination. Olive Notes. Univ. California Agr. Natural Resources Bul. 9(2). 25 Oct. 2018. <https://ucanr.edu/datastoreFiles/832-33.pdf>
GriggsW.HartmannH.BradleyM.V.IwakiriB.T.WhislerJ.1975Olive pollination in California. Univ. California California Agr. Expt. Sta. Bul. 869
GuerinJ.SedgleyM.2007Cross-pollination in olive cultivars. Rural Ind. Res. Dev. Corp. Austral. Austral. Govt. Barton Canberra Austral. p. 1–43
Heslop-HarrisonJ.Heslop-HarrisonY.1970Evaluation of pollen viability by enzymatically induced fluorescence intracellular hydrolysis of fluorescein diacetateStain Technol.451520
LaveeS.TaryanJ.LevinJ.HaskalA.2002The significance of cross-pollination for various olive cultivars under irrigated intensive growing conditionsOlivae912536
Navarro-AinzaJ.A.C.Fimbres-FontesA.López-CarbajalA.Robles-ContrerasF.2010Demonstration plots yield established with pollination and irrigation in commercial olive orchards (Olea europaea L.)Rev. Chapingo Ser. Zonas Áridas96166
Navarro-AinzaJ.A.C.López-CarvajalA.2013Cuajado de frutos y partenocarpia en olivo ‘Manzanilloʼ con polinización cruzadaAgron. Mesoam.24393400
PinillosV.CuevasJ.2009Open-pollination provides sufficient levels of cross-pollen in Spanish monovarietal olive orchardsHortScience44499502
RejanoL.MontañoA.CasadoF.J.SánchezA.H.de CastroA.2010Table olives: Varieties and variations p. 5–15. In: V.R. Preedy and R.R. Watson (eds.). Olives and olive oil in health and disease prevention. Elsevier Amsterdam The Netherlands
Ruíz-CorralJ.A.Medina-GarcíaG.Grajeda-GrajedaJ.Silva-SernaM.M.Díaz-PadillaG.2005Estadísticas climatológicas básicas del Estado de Sonora (periodo 1961–2003). Libro Técnico No. 1. Instituto Nacional Investigaciones Forestales Agrarias y Pecuarias—Campo Investigación Regional Noroeste—Secretaría Agricultura Ganadería Desarrollo Rural Pesca y Alimentación. Cd. Obregón Sonora México
SeifiE.GuerinJ.KaiserB.SedgleyM.2012Sexual compatibility of the olive cultivar ‘Kalamataʼ assessed by paternity analysisSpan. J. Agr. Res.10731740
ShemerA.BitonI.ManyY.VakninY.LaveeS.AvidanB.Ben-AriG.2014The olive cultivar ʻPicualʼ is on optimal donor for ‘BarneaʼScientia Hort.172278284
SibbettG.S.FergusonL.MartinG.C.1994Olive production manual. Univ. California Agr. Natural Resources Oakland
SibbettG.S.FreemanM.FergusonL.PolitoV.S.1992Effect of topically applied ‘Sevillano’ pollen on normal-seeded and parthenocarpic “shotberry” fruit set of ‘Manzanilloʼ oliveHortTechnology2228230
Vuletin-SelakG.PericaS.Goreta BanS.PoljakM.2014The effect of temperature and genotype on pollen performance in olive (Olea europaea L.)Scientia Hort.1563846
Pollen tube growth dynamic in the style of self-, open- and cross-pollinated flowers of ‘Manzanilloʼ olive trees in 2016.
Pollen tube growth dynamic in the style of self-, open-, and cross-pollinated flowers of ‘Manzanilloʼ olive trees in 2017.
Chi-square distribution table of number of fertilized flowers on each day sampled of self-, open-, and cross-pollinated flowers of ‘Manzanilloʼ olive trees in 2016. Values are of the observed flowers, between parenthesis expected values.
Chi-square distribution table of number of fertilized flowers of self-, open-, and cross-pollinated flowers of ‘Manzanilloʼ olive trees in 2017. Values are of the observed flowers, and those in parentheses are expected values.