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

Gilat Research Centre, Agricultural Research Organization, Ministry of Agriculture, Mobile Post Negev 85280, Israel; 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 01/2010; DOI: 10.1016/j.scienta.2009.11.014

ABSTRACT 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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    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.
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    ABSTRACT: In drupe-type fruits, pit hardening, resulting from sclerification of the fruit endocarp, is widely used as a phenological marker for both physiological studies and orchard management. In spite of the importance of pit hardening for understanding fruit development processes and for agricultural practices, however, its quantification has remained obscure and precision has been lost with time and lax usage. In this study we used a mechanical device to measure the physical pressure required to break the olive pit in order to define the timing of pit hardening more precisely and to permit closer observation of its relationship to fruit and endocarp growth and development. Over four years we found that pit-hardening pressure increased following a sigmoid pattern, at first gradually but then with a large and rapid increment of change in a relatively short period of time. The rapid acceleration of hardening began at the time when pit longitudinal and transverse diameters attained their maximum size. That timing is consistent with the anatomical differentiation of the sclerified endocarp cells which can no longer expand nor divide. The results improve our knowledge of pit hardening and provide a more precise context for evaluating the metabolic costs, physiological interactions and genetic controls of stone fruit endocarp development. On a practical level, the association of the intensification of pit-breaking pressure with the cessation of pit expansion indicates that pit diameters can be useful morphological markers to identify the onset of this period.
    Annals of Applied Biology 01/2013; 163:200-208. · 2.15 Impact Factor
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Oct 5, 2014