Fruit pit hardening: physical measurement during olive fruit growth

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 4 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.

Cell and tissue dynamics of olive endocarp sclerification vary according to water availability

“…By t 2 or pit hardening, that area represented 75–80% of the endocarp, but beyond that time histological observations could no longer be carried out with the methods we used. Increased physical pressure required to break the pit (Rapoport et al ) and observation of completely woody pits in mature fruits confirm the continuation of sclerification after t 2 .…”

“…Biochemical analyses of endocarp lignification in peach indicate two phases: first gradual and later exponential (Ryugo , Hayama et al , Hu et al ). When pit hardening is measured physically, a sudden incremental change occurs in the pressure required to crush the nectarine (King et al ) and olive pits (Rapoport et al ). Quantitative analysis of sclereid cell distribution revealed the overall intensification of sclerification as a dramatic increment in area of the sclerified clusters.…”

Changes in the physiological response between leaves and fruits during a moderate water stress in table olive trees

“…The beginning of the pit hardening was estimated according to Rapoport et al (2013) around day of the year (DOY) 173. From this date until DOY 233 irrigation was withdrawn in a Stressed treatment (Phase II).…”

Umbrales Sostenibles De Estrés Hídrico Durante El Endurecimiento Del Hueso en La Producción De Aceituna De Mesa

“…Esta fase engloba la plena floración (que suele tener lugar para el año medio a mediados de Abril) y es considerada la más sensible al estrés hídrico (Moriana et al, 2003).. El inicio de brotación habitualmente ocurre desde final de Febrero y el comienzo del endurecimiento masivo del hueso en la última semana de Junio. La determinación del comienzo del endurecimiento masivo se realizó según Rapoport et al (2013) que brevemente consiste en medir la longitud de la aceituna, cuando hay un cambio en la tasa de crecimiento se considera que ha comenzado este proceso. En el año medio durante este periodo las necesidades de riego suelen ser pequeñas por el régimen pluviométrico de la zona.…”