Fruit load governs transpiration of olive trees

Abstract

We tested the hypothesis that whole-tree water consumption of olives (Olea europaea L.) is fruit load-dependent and investigated the driving physiological mechanisms. Fruit load was manipulated in mature olives grown in weighing-drainage lysimeters. Fruit was thinned or entirely removed from trees at three separate stages of growth: early, mid and late in the season. Tree-scale transpiration, calculated from lysimeter water balance, was found to be a function of fruit load, canopy size and weather conditions. Fruit removal caused an immediate decline in water consumption, measured as whole-plant transpiration normalized to tree size, which persisted until the end of the season. The later the execution of fruit removal, the greater was the response. The amount of water transpired by a fruit-loaded tree was found to be roughly 30% greater than that of an equivalent low- or nonyielding tree. The tree-scale response to fruit was reflected in stem water potential but was not mirrored in leaf-scale physiological measurements of stomatal conductance or photosynthesis. Trees with low or no fruit load had higher vegetative growth rates. However, no significant difference was observed in the overall aboveground dry biomass among groups, when fruit was included. This case, where carbon sources and sinks were both not limiting, suggests that the role of fruit on water consumption involves signaling and alterations in hydraulic properties of vascular tissues and tree organs.

Root Development of Bell Pepper (Capsicum annuum L.) as Affected by Water Salinity and Sink Strength

“…While Nielsen and Veierskov [11] did not find an effect of fruit load on root to shoot ratio of bell pepper, our results indicate that fruit removal changed the root/shoot balance in favor of the shoot. Several reports indicated that high sink strength led to an increase in stomatal conductance and transpiration [37,38]. The reported increase in stomatal conductance in the presence of strong sink might compensate for the substantial decrease in shoot (leaves and branches) growth compared with root growth.…”

A possible role for flowering locus T‐encoding genes in interpreting environmental and internal cues affecting olive (Olea europaea L.) flower induction

“…There is a clear trade‐off between fruit and vegetative growth in olive (Bustan et al . ). Here we provide evidence that the few lateral meristems formed during an ‘on’ year do not produce inflorescences.…”

“…As already noted, this is partially due to a severe reduction in growth, leading to much fewer new lateral buds formed on the branch. There is a clear trade-off between fruit and vegetative growth in olive (Bustan et al 2016). Here we provide evidence that the few lateral meristems formed during an 'on' year do not produce inflorescences.…”

Carbon Isotope Discrimination (δ13 C) of Grape Musts Is a Reliable Tool for Zoning and the Physiological Ground-Truthing of Sensor Maps in Precision Viticulture

“…Therefore, in these regions, commercial grapevine production relies on supplemental irrigation. The sustainability of grapevine production is there under threat due to growing water scarcity, rising global temperatures, and suboptimal irrigation strategies (White et al, 2006;Diffenbaugh and Scherer, 2013;Bustan et al, 2016;Bonfante et al, 2018). This problem is especially meaningful considering that grapevine is economically viable in soils with reduced fertility not well suited to other crops and that Mediterranean ecosystems adapted to grapevine are global biodiversity hotspots (Myers et al, 2000).…”