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.
Ayerza, R. & Coates, W. 2004 Supplemental pollination – increasing olive (Olea europaea) yields in hot, arid environments Expt. Agr. 40 481 491
Cuevas, J., Díaz-Hermoso, A.J., Galián, D., Hueso, J.J., Pinillos, V., Prieto, M., Sola, D. & Polito, V.S. 2001 Response to cross-pollination and choice of pollinisers for the olive cultivars (Olea europaea L.) ‘Manzanilla de Sevilla’, ‘Hojiblanca’ and ‘Picual’ Olivae 85 26 32
Dimassi, K., Therios, I. & Balatsos, A. 1999 The blooming period and self-fruitfulness in twelve Greek and three foreign olive cultivars Acta Hort. 474 275 278
Farinelli, D., Pierantozzi, P. & Palese, A.M. 2012 Pollenizer and cultivar influence seed number and fruit characteristics in Olea europaea L HortScience 47 1430 1437
Fernández-Escobar, R. & Rallo, L. 1981 Influencia de la polinización cruzada en el cuajado de frutos de cultivares de olivo (Olea europaea L.) Inf. Téc. Econ. Agrar. 45 51 58
Fichtner, E.J. 2012 Olive bloom and pollination. Olive Notes. Univ. California Agr. Natural Resources Bul. 9(2). 25 Oct. 2018. <https://ucanr.edu/datastoreFiles/832-33.pdf>
Griggs, W., Hartmann, H., Bradley, M.V., Iwakiri, B.T. & Whisler, J. 1975 Olive pollination in California. Univ. California, California Agr. Expt. Sta. Bul. 869
Guerin, J. & Sedgley, M. 2007 Cross-pollination in olive cultivars. Rural Ind. Res. Dev. Corp. Austral. Austral. Govt. Barton, Canberra, Austral. p. 1–43
Heslop-Harrison, J. & Heslop-Harrison, Y. 1970 Evaluation of pollen viability by enzymatically induced fluorescence intracellular hydrolysis of fluorescein diacetate Stain Technol. 45 15 20
Lavee, S., Taryan, J., Levin, J. & Haskal, A. 2002 The significance of cross-pollination for various olive cultivars under irrigated intensive growing conditions Olivae 91 25 36
Navarro-Ainza, J.A.C., Fimbres-Fontes, A., López-Carbajal, A. & Robles-Contreras, F. 2010 Demonstration plots yield established with pollination and irrigation in commercial olive orchards (Olea europaea L.) Rev. Chapingo Ser. Zonas Áridas 9 61 66
Navarro-Ainza, J.A.C. & López-Carvajal, A. 2013 Cuajado de frutos y partenocarpia en olivo ‘Manzanilloʼ con polinización cruzada Agron. Mesoam. 24 393 400
Pinillos, V. & Cuevas, J. 2009 Open-pollination provides sufficient levels of cross-pollen in Spanish monovarietal olive orchards HortScience 44 499 502
Rejano, L., Montaño, A., Casado, F.J., Sánchez, A.H. & de Castro, A. 2010 Table 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-Corral, J.A., Medina-García, G., Grajeda-Grajeda, J., Silva-Serna, M.M. & Díaz-Padilla, G. 2005 Estadísticas 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
Seifi, E., Guerin, J., Kaiser, B. & Sedgley, M. 2011 Sexual compatibility and floral biology of some olive cultivars N. Z. J. Crop Hort. Sci. 39 141 151
Seifi, E., Guerin, J., Kaiser, B. & Sedgley, M. 2012 Sexual compatibility of the olive cultivar ‘Kalamataʼ assessed by paternity analysis Span. J. Agr. Res. 10 731 740
Shemer, A., Biton, I., Many, Y., Vaknin, Y., Lavee, S., Avidan, B. & Ben-Ari, G. 2014 The olive cultivar ʻPicualʼ is on optimal donor for ‘Barneaʼ Scientia Hort. 172 278 284
Sibbett, G.S., Ferguson, L. & Martin, G.C. 1994 Olive production manual. Univ. California, Agr. Natural Resources, Oakland
Sibbett, G.S., Freeman, M., Ferguson, L. & Polito, V.S. 1992 Effect of topically applied ‘Sevillano’ pollen on normal-seeded and parthenocarpic “shotberry” fruit set of ‘Manzanilloʼ olive HortTechnology 2 228 230
Vuletin-Selak, G., Perica, S., Goreta Ban, S. & Poljak, M. 2014 The effect of temperature and genotype on pollen performance in olive (Olea europaea L.) Scientia Hort. 156 38 46
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.