Gilat Research Centre, Agricultural Research Organization, Ministry of Agriculture, Mobile Post Negev 85280, Israel.
Tree Physiol. 2011 May;31(5):519-30. doi: 10.1093/treephys/tpr036. Epub 2011 May 12.
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.
油橄榄（Olea europaea）具有很强的年度产量波动（隔年结果）倾向，这对橄榄油产业有负面影响。在隔年结果的可能原因中，通常提到在高产年（On-year）储存的碳水化合物（CHO）被耗尽。本研究的目的是验证 CHO 储备作为隔年结果的原因或结果的作用。在 2005 年 11 月至 2006 年 10 月的一个完整生殖周期中，对 On-和 Off-树（品种 Barnea）的叶片、树枝、树皮和根系中的可溶性糖和淀粉浓度进行了每月调查。1 月还测定了心材中的碳水化合物浓度，并估计了整树的生物量。树干和树枝拥有最大部分的 CHO 储备。还研究了减少果实负载对 CHO 储备的影响。在所有组织中，淀粉、甘露醇和蔗糖浓度从 12 月到 3 月增加，然后随着果实发育而下降。叶片、树枝和树皮在 CHO 储存中具有重要作用，而根系积累的 CHO 浓度最低。然而，储备含量的波动表明根系在 CHO 预算中具有相当大的作用。尽管如此，在 On-和 Off-树之间，CHO 浓度的年度模式没有明显差异。即使果实数量减少 75-100%，CHO 含量也只是略有缓慢增加，尽管在根部更为明显。即使在对果实和油产量的最大需求下，碳水化合物储备也没有耗尽。因此，在橄榄中，CHO 储备的状况不是产量的决定因素。然而，它们可能在橄榄的生存策略中发挥重要作用，确保树木在不可预测的半干旱地中海环境中恢复。这表明橄榄中的 CHO 储备像一个活跃的库，挑战了关于植物中 CHO 储备调节的常见概念。
