Pollination Strategies to Improve Fruit Set in Orchards of ‘Manzanilloʼ Olive in a Nontraditional Producing Country, Mexico

Abstract

<jats:p>In countries new to producing ‘Manzanillo’ olive trees (<jats:italic>Olea europaea</jats:italic>), free cross-pollination is often insufficient to obtain high levels of fruit set. An appropriate pollination design is therefore essential to ensure a timely, abundant, and compatible pollen supply. With a view to determining whether a pollination deficit exists in a nontraditional olive area such as the northern Mexico, pollination experiments were carried out in two consecutive seasons in both a monovarietal and a multivarietal Manzanillo orchard, where Sevillano, Barouni, Picual, Pendolino, Mission, Nevadillo, and Frantoio trees were growing nearby. The pollination treatments were self-, open, and cross-pollination with ‘Barouni’ and ‘Sevillano’ pollen, the latter only in the multivarietal orchard. The results confirmed the full self-incompatible condition of ‘Manzanillo’. Open-pollination did not improve fruit set in the monovarietal orchard, but it did so significantly in the multivarietal plot, where fruit set levels under open-pollination matched those of cross-pollination. Lower pollen adhesion, as well as occasional decreased germination, and reduced and delayed pollen tube growth were observed under self-pollination, highlighting self-incompatibility reactions. The reduction in fertilization rates led to low fruit set under self-pollination. Positive effects of open- and cross-pollination treatments were also noted on fruit weight (despite higher crop loads) and pulp-to-pit ratios. A strategic plantation design, including appropriate pollinizers in the right number and position, is therefore suggested for increasing ‘Manzanillo’ fruit quality and yield in Mexico. Both ‘Barouni’ and ‘Sevillano’ served as efficient pollinizers for ‘Manzanillo’, although we recommend ‘Barouni’ as a more efficient because the bloom periods of them matched that of ‘Manzanillo’</jats:p>

Profitability of Artificial Pollination in ‘Manzanillo’ Olive Orchards

“…In this season, we found a higher level of initial and final set with an increase in the number of pollinations, matching the results reported by Sibbett et al [14], applying the same number of applications at a rate of 75 g ha −1 of 'Sevillano' undiluted pollen at the same phenological stages. 'Sevillano' pollen induced a fruit set similar to 'Barouni' pollen on 'Manzanillo', as demonstrated in a recent research carried out in the experimental area [9]. Similar results have been obtained in some European countries.…”

“…Olive is an andromonoecious species-that is, it forms male and hermaphrodite flowers, usually within the same panicle. Flowers in the experiment were kept under open pollination conditions, but in an isolated monovarietal orchard, where we previously had demonstrated a strong dependence on cross-pollination to obtain a sizable yield [9].…”

“…Yield (kg tree −1 ) was estimated by taking into account the flowering intensity of each tree, the average flower number per panicle in 'Manzanillo' trees (9.74), recorded in a parallel experiment [9], the percentage of fertile panicles, i.e., possessing at least one hermaphroditic flower (88.7%), and final fruit set and mass (g) at harvest. Finally, the incomes derived from the different pollination treatments were compared based on yield and market price for each fruit size category [38].…”

“…This dependence is clear for 'Manzanillo' [4], the most extensively grown and esteemed table olive cultivar in the world [5]. Monovarietal orchards of 'Manzanillo' in isolated locations, without the benefits of free cross-pollination, suffer from severe pollen deficits [6][7][8][9], significantly reducing their flower fertilization and fruit set [4,10]. The usual measure to overcome pollen deficits in tree crops is to design plantations with the right number of pollinizers (pollen donor trees), with the right distance from the main variety, and in the right patterns.…”

Flowering Behavior of French Olive Cultivar ‘Picholine’ Under Syrian Coast Conditions

“…Pistil abortion (%) = (number of flowers with non-functional pistils/ total number of flowers) ×100. Fertile inflorescences (%) = (number of inflorescences containing at least one hermaphrodite flower/ total number of inflorescences) × 100 (Sanchez-Estrada and Cuevas, 2020).…”