Timing of fruit removal affects concurrent vegetative growth and subsequent return bloom and yield in olive (Olea europaea L.). Sci Hortic

The Kennedy-Leigh Centre for Horticultural Research, The Robert H. Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem, Rehovot 76100, Israel
Scientia Horticulturae (Impact Factor: 1.37). 02/2010; 123(4):469-472. DOI: 10.1016/j.scienta.2009.11.014


Olive (Olea europaea) demonstrates a high tendency toward alternate fruit production, with significant negative consequences on the industry. Fruit load is one of the main cause-and-effect factors in the phenomenon of biennial bearing, often disrupting the balance between reproductive and vegetative processes. The objectives of the present study were to identify the time range during which heavy fruit load reversibly interrupts the reproductive processes of the following year. The linkage between timing of fruit removal, vegetative growth, return bloom, and fruit yield was studied. Complete fruit removal in cv. Coratina until about 120 days after full bloom (August 15) caused an immediate resumption of vegetative growth. The new shoots grew to twice the length of those on trees that underwent later fruit removal. Moreover, a full return bloom, corresponding with high subsequent yields, was obtained by early fruit removal, while poor or no bloom developed on late-defruited or control trees. Thus, the critical time to affect flowering and subsequent fruiting in the following year by fruit thinning occurs in olive trees even weeks after pit hardening—much later than previously suggested. Furthermore, the data indicate that flowering-site limitation, due to insufficient or immature vegetative growth during the On-year, is a primary factor inducing alternate bearing in olive.

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Available from: Arnon Dag, Oct 05, 2014
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    • "When partial fruit thinning is practiced, shoot length is also most often greater at the end of the season (Proietti and Tombesi, 1996). Shoot elongation has been found to have the capacity to increase even when fruit are removed up to 120 days after full bloom (i.e., mid-summer) (Dag et al., 2010). In terms of reproductive growth, both individual fruit weight and pulp-to-pit ratio are consistently greater in olive when crop load is low (Barone et al., 1994; Proietti et al., 2006; Gucci et al., 2007; Trentacoste et al., 2010). "
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    ABSTRACT: The need to understand how the balance between vegetative and reproductive growth in olive trees is modified by different crop loads has become more important over the last 20 years due to increasing planting densities and the greater use of irrigation. The objectives of this study conducted in a well-irrigated olive orchard were to: (1) evaluate shoot and fruit growth dynamics following fruit thinning during the same growing season in which thinning was applied and during the next growing season; and to (2) determine crop load effects on bloom, fruit set, and fruit yield over three growing seasons. Hand-thinning of fruit 35 days after full bloom on 9-year-old cv. ‘Arauco’ trees in an “on” year led to thinning treatments of 24, 48, and 87% with respect to an unthinned control. Apical and lateral shoot elongation were measured every two weeks throughout the growing season, and fruit were sampled to determine fruit weight at the same interval. Apical shoot elongation occurred only early in the season when crop load was medium or high, while apical elongation continued for most of the season when crop load was low. Elongation of laterals contributed significantly to total shoot elongation on fruit-bearing branches in trees with low crop loads after thinning the first season. Individual fruit dry weight was reduced about 40% by high crop loads in both seasons. Differences in relative growth rates of both the shoots and the fruit due to crop load suggest fruit growth was limited by photoassimilate availability early in the season, but shoot growth was limited most of the season under medium and high crop loads. Inflorescence number per shoot was reduced by crop load in the two seasons following the thinning event. Fresh fruit yield was only reduced in one of the two biennia (i.e., periods of 2 years) in the trees that were heavily thinned (87%) the first season. The trees in which about one-half (48%) of the fruit were thinned the first season did not show biennia yield reductions and maintained a low alternate bearing index over three seasons. Thus, chemical thinning could be applied in growing seasons with high flowering. Further studies are needed to better assess competition for resources between shoots and fruit with the ultimate goal of reducing alternate bearing.
    Scientia Horticulturae 08/2015; 192. DOI:10.1016/j.scienta.2015.06.028 · 1.37 Impact Factor
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    • "A pattern of alternate bearing has been documented for many species (see, e.g., Monselise and Goldschmidt 1982; Crawley and Long 1995; Stevenson and Shackel 1998). Many fruit trees, such as apples (Jonkers 1979), pistachio (Stevenson et al. 2000; Roussos et al. 2004), olive (Dag et al. 2010) etc., have an intrinsic tendency to exhibit alternation of large and small crop years independent of environmental variables such as weather conditions. For oak species, Q. crispula (Q. "
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    ABSTRACT: Many masting species switch resources between vegetative growth and reproduction in mast and non-mast years. Although masting of oak species is well known, there have been few investigations of the relationship between vegetative growth and reproduction based on long-term monitoring data, especially in evergreen oaks of subgenus Cyclobalanopsis. We investigated annual variations over 13 years in acorn and leaf production of three evergreen oak species in subgenus Cyclobalanopsis, genus Quercus (Fagaceae)—Q. acuta, Q. salicina and Q. sessilifolia—in western Japan. In these species, the maturation of acorns occurs in the second autumn after flowering, which is known as a biennial-fruiting habit. We found a pattern of acorn production and masting in alternate years that was synchronized in all three species. Masting was not correlated with temperature and precipitation. Annual leaf-fall also showed 2-year cycle in the three oak species; peak years were synchronized between species and peak leaf-fall alternated with acorn production in all three species. Furthermore, there was a significant negative correlation between acorn and leaf production in all three species. Data showing 2-year cycles of acorn and leaf production and the negative correlation between them supports the hypothesis of resource switching between vegetative growth and reproduction. The 2-year cycle might be the basic, intrinsic rhythm of resource allocation in biennial-fruiting Cyclobalanopsis species.
    Ecological Research 10/2014; 27(6). DOI:10.1007/s11284-012-0986-9 · 1.30 Impact Factor
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    • "Severe or complete removal of the fruits brings considerable vegetative growth, bloom and fruit yield in the following year (Dag et al., 2010), although it does not seem to intensely alter the carbohydrate reserves at the end of the olive reproductive cycle (Bustan et al., 2011). "
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    ABSTRACT: Olive (Olea europaea L.) shows alternate bearing, with unreliable cropping patterns and inconsistent fruit size and quality every year. In many countries, thinning with naphthaleneacetic acid (NAA) is used to minimise alternate bearing behavior in olives. However, in Italy, growers are reluctant to employ this practice and no detailed knowledge is available for specific cultivars. We evaluated the effects of spraying NAA on various dates on the productive and vegetative characteristics of the main Italian table olive cultivar'Nocellara del Belice'. Trunk cross-sectional area, fruit set, fruit drop, fruit size, pit size, yield per tree, crop density and flesh to pit ratio were analysed. The NAA treatment applied on the earliest of the dates selected increased fruit weight and flesh to pit ratio, by reducing crop density and enhancing the leaf to fruit ratio, without reducing yield. Two distinct negative relationships were found between fruit weight and crop density during "on" and "off" years, but a unique relationship between pit weight vs. crop density in both years, suggested that the pit is the strongest sink. Fruit size and quality of'Nocellara del Belice' can be enhanced by NAA application, thereby increasing economic returns in the "on" year.
    Scientia Agricola 01/2014; 71(1-1):52-57. DOI:10.1590/S0103-90162014000100007 · 0.81 Impact Factor
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