Role of carbohydrate reserves in yield production of intensively cultivated oil olive (Olea europaea L.) trees

Abstract

Olive (Olea europaea) has a very high tendency for year-to-year deviation in yield (alternate bearing), which has a negative economic impact on the olive oil industry. Among possible reasons for alternate bearing, depletion of stored carbohydrates (CHO) during the On-year (high yield) has often been mentioned. The objective of the present study was to verify the role of CHO reserves, as a cause or effect, in the alternate bearing of intensively cultivated olives. A monthly survey of soluble sugar and starch concentrations in the leaves, branches, bark and roots of On- and Off-trees (cv. Barnea) was carried out during a complete reproductive cycle from November 2005 to October 2006. Carbohydrate concentration in the sapwood was determined in January, as well as an estimate of whole-tree biomass. The trunk and limbs possess the largest portion of CHO reserves. The influence of reduced fruit load on CHO reserves was also investigated. Starch, mannitol and sucrose concentrations increased from December to March in all tissues, and then declined along with fruit development. Leaves, branches and bark have a significant role in CHO storage, whereas roots accumulated the lowest CHO concentrations. However, fluctuations in reserve content suggested considerable involvement of roots in the CHO budget. Nevertheless, there were no meaningful differences in the annual pattern of CHO concentration between On- and Off-trees. Even a 75-100% reduction in fruit number brought about only a minor, sluggish increase in CHO content, though this was more pronounced in the roots. Carbohydrate reserves were not depleted, even under maximum demands for fruit and oil production. It is concluded that in olives, the status of CHO reserves is not a yield determinant. However, they may play a significant role in the olive's survival strategy, ensuring tree recovery in the unpredictable semiarid Mediterranean environment. This suggests that CHO reserves in olive act like an active sink, challenging the common concept regarding the regulation of CHO reserves in plants.

Improvement in yield and fruit size and quality of the main Italian table olive cultivar 'Nocellara del Belice'

“…Proietti (2000) reported no clear correlation between heavy fruit load and photosynthesis effi ciency, concluding that the depletion of carbohydrate reserves during an "on" year could negatively infl uence new leaves and thus fl ower bud formation. However, Bustan et al (2011) recently showed that carbohydrate surplus or defi ciency cannot be considered the cause of olive alternate bearing, thus, this phenomenon is probably regulated by hormonal factors (Stutte and Martin 1986;Ulger et al, 2004;Dag et al, 2009Dag et al, , 2010. On the whole, carbohydrate resources fl uctuate in response to sharp changes in source-sink relationships in the tree throughout the season playing a role in olive survival strategy (Bustan et al, 2011).…”

“…However, Bustan et al (2011) recently showed that carbohydrate surplus or defi ciency cannot be considered the cause of olive alternate bearing, thus, this phenomenon is probably regulated by hormonal factors (Stutte and Martin 1986;Ulger et al, 2004;Dag et al, 2009Dag et al, , 2010. On the whole, carbohydrate resources fl uctuate in response to sharp changes in source-sink relationships in the tree throughout the season playing a role in olive survival strategy (Bustan et al, 2011). Our results suggest that the carbohydrate reserve level may limit mesocarp growth, while pit weight seems to be infl uenced only by the current year's photo-assimilate availability.…”

“…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). Rather than carbohydrate reserves, it is likely that the main factor responsible for the alternate bearing phenomenon is constituted by inhibitor signals produced by the developing embryos (Lavee, 2007).…”

Economics of Oil Production from Pongamia (Millettia pinnata) for Biofuel in Australia

“…Yield estimates from India are often sourced from individual trees rather than being based on the average of a plantation over several seasons [30,34]. For comparison purposes, it is worth noting that the seed yield of commercial orchards of macadamia and almonds tends to range between 5 and 20 kg of nuts in shells per tree per annum, equivalent to about 1 to 6 t per hectare at planting densities of 200 to 320 trees per hectare [13,22,35,41,47]. The lower yield estimates are for non-irrigated groves.…”

Papel do metabolismo de carboidratos nas respostas ecofisiológicas da árvore amazônica Senna reticulata cultivada sob diferentes estresses abióticos

“…A proeminente redução da respiração foliar parece ter sido peça fundamental nessa regulação, direcionando carboidratos para aumento de reserva e de crescimento, reforçando a partição equilibrada entre esses dois processos. Esses resultados adicionam elementos no entendimento de como ocorreu o efeito de tamponamento observado por quando a mesma espécie foi submetida à elevada concentração de CO 2 acoplada ao alagamento, reforçando a ideia de que a plasticidade presente no sistema de armazenamento da planta (partição entre crescimento e armazenamento equilibrado), bem como a possibilidade de uso destas reservas (disponibilidade) são fatores relevantes a manutenção do crescimento (Bustan et al, 2011;Sala et al, 2012).…”