Hydraulic traits emerge as relevant determinants of growth patterns in wild olive genotypes under water stress

15 páginas.-- 5 figuras.-- 3 tablas.-- 81 referencias.--The Supplementary Material for this article can be found online at: https://www.frontiersin.org/articles/10.3389/fpls.2019.00291/full#supplementary-material.-- This Research Topic aims to collect selected contributions to Olivebioteq 2018, the 6th International Conference on Olive Management and Olive Products, held in Seville, Spain, on 15th-19th October 2018.

The hydraulic traits of plants, or the efficiency of water transport throughout the plant hydraulic system, could help to anticipate the impact of climate change and improve crop productivity. However, the mechanisms explaining the role of hydraulic traits on plant photosynthesis and thus, plant growth and yield, are just beginning to emerge. We conducted an experiment to identify differences in growth patterns at leaf, root and whole plant level among four wild olive genotypes and to determine whether hydraulic traits may help to explain such differences through their effect on photosynthesis. We estimated the relative growth rate (RGR), and its components, leaf gas exchange and hydraulic traits both at the leaf and whole-plant level in the olive genotypes over a full year. Photosynthetic capacity parameters were also measured. We observed different responses to water stress in the RGRs of the genotypes studied being best explained by changes in the net CO2 assimilation rate (NAR). Further, net photosynthesis, closely related to NAR, was mainly determined by hydraulic traits, both at leaf and whole-plant levels. This was mediated through the effects of hydraulic traits on stomatal conductance. We observed a decrease in leaf area: sapwood area and leaf area: root area ratios in water-stressed plants, which was more evident in the olive genotype Olea europaea subsp. guanchica (GUA8), whose RGR was less affected by water deficit than the other olive genotypes. In addition, at the leaf level, GUA8 water-stressed plants presented a better photosynthetic capacity due to a higher mesophyll conductance to CO2 and a higher foliar N. We conclude that hydraulic allometry adjustments of whole plant and leaf physiological response were well coordinated, buffering the water stress experienced by GUA8 plants. In turn, this explained their higher relative growth rates compared to the rest of the genotypes under water-stress conditions.

This work was supported by the Spanish Ministry of Science and Innovation through the research project AGL2015-71585-R and PCIN-2017-002. Funding was also received from a “RECUPERA-2020” FEDER-MINECO grant (Ref. 20134R089) and a “Grupos Operativos” FEDER-MAPAMA grant (Ref. 20160020006629). CR-D benefited from an Individual Fellowship from the European Union’s Horizon 2020 Research and Innovation Program under the Marie Skłodowska-Curie grant agreement no. 751918-AgroPHYS during the writing process of the manuscript.

Peer reviewed