Suchergebnisse

10 páginas.- 5 figuras.- 2 tablas.- 71 referencias.- Supplementary material related to this article can be found, in the online version, at doi: https://doi.org/10.1016/j.agrformet.2019.04.006 ; Effective study and management of crops and forests would benefit greatly from useful plant-based indicators of the biological controls on evapotranspiration, and particularly stomatal conductance (g s ). Given the strong influence of g s on bulk leaf water potential and turgor pressure (P), in vivo measurement of P may provide useful information about diurnal or seasonal dynamics of g s . Moderate plant water stress affects the diurnal dynamics of P as leaf-to-air vapour pressure deficit (D) varies, and these dynamics correlate to g s . Here, we explored relative changes in P in response to changes in D under mild drought conditions, and how these changes are linked to stomatal behaviour, and specifically to diurnal maximum g s (g s,max ), one of the best indicators of plant water stress. We monitored ecophysiological and environmental variables, as well as a relative proxy for P, during three consecutive seasons in a hedgerow olive orchard where trees were supplied with different irrigation treatments to create well-watered and moderately water-stressed conditions. Our results demonstrated that the sensitivity of P to D correlated well with g s,max reached by the trees within a range in which variations in g s are the main diffusional limitation to photosynthesis. We further showed that this correlation held under a wide range of meteorological conditions and soil water availability. This turgor proxy measurement, which is much easier to measure than g s , can facilitate the use of g s,max as an indicator of plant water stress and evapotranspiration in agriculture and plant science research. © 2019 The Authors ; This work was funded by the Spanish Ministry of Science and Innovation (research project AGL2009-11310/AGR ) and co-funded by FEDER programme . C. M. R-D benefited from a FPDI research fellowship from the Junta de Andalucía during the data gathering and from an Individual Fellowship from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No. 751918-AgroPHYS during the writing process of the manuscript. TNB was supported by the National Science Foundation (Award 1557906) and by the USDA National Institute of Food and Agriculture, Hatch project 1016439. We are grateful to the members of the Irrigation and Crop Ecophysiology group from IRNAS-CSIC for assistance in the field, especially to Antonio Montero and Alfonso Perez-Martin, and to Alfonso de Cires for helping on osmotic pressure measurements. We also thank the owners of Internacional Olivarera, S.A.U. (Interoliva) for allowing us to conduct the experiments in the Sanabria orchard, and Tim J. Brodribb for constructive inputs. ; Peer reviewed

13 páginas.- 7 figuras.- 92 referencias.- ; The mechanisms by which woody plants recover xylem hydraulic capacity after drought stress are not well understood, particularly with regard to the role of embolism refilling. We evaluated the recovery of xylem hydraulic capacity in young Eucalyptus saligna plants exposed to cycles of drought stress and rewatering. Plants were exposed to moderate and severe drought stress treatments, with recovery monitored at time intervals from 24 h to 6 months after rewatering. The percentage loss of xylem vessels due to embolism (PLV) was quantified at each time point using microcomputed tomography with stem water potential (Ψx) and canopy transpiration (Ec) measured before scans. Plants exposed to severe drought stress suffered high levels of embolism (47.38% ± 10.97% PLV) and almost complete canopy loss. No evidence of embolism refilling was observed at 24 h, 1 week, or 3 weeks after rewatering despite rapid recovery in Ψx. Recovery of hydraulic capacity was achieved over a 6-month period by growth of new xylem tissue, with canopy leaf area and Ec recovering over the same period. These findings indicate that E. saligna recovers slowly from severe drought stress, with potential for embolism to persist in the xylem for many months after rainfall events. © 2022 John Wiley & Sons Ltd. ; This study was supported by an ARC Discovery Project (DP170100761) to BC and TJB and an ARC Future Fellowship (FT130101115) to BC. BM acknowledges support from the ARC Laureate Fellowship FL190100003. CMR‐D was supported by an Individual Fellowship from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska‐Curie grant agreement no. 751918‐AgroPHYS. JMRP was supported by the ORNL, managed by UT‐Battelle, LLC, for the DOE under contract DE‐AC05‐1008 00OR22725. ; Peer reviewed

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

25 páginas.- 8 figuras.- 2 tablas.- 66 referencias.- Additional supporting information can be found online in the Supporting Information section at the end of this article. ; eaf water potential (psi(leaf)), typically measured using the pressure chamber, is the most important metric of plant water status, providing high theoretical value and information content for multiple applications in quantifying critical physiological processes including drought responses. Pressure chamber measurements of psi(leaf) (psi(leafPC)) are most typical, yet, the practical complexity of the technique and of the underlying theory has led to ambiguous understanding of the conditions to optimize measurements. Consequently, specific techniques and precautions diversified across the global research community, raising questions of reliability and repeatability. Here, we surveyed specific methods of psi(leafPC) from multiple laboratories, and synthesized experiments testing common assumptions and practices in psi(leafPC) for diverse species: (i) the need for equilibration of previously transpiring leaves; (ii) leaf storage before measurement; (iii) the equilibration of psi(leaf) for leaves on bagged branches of a range of dehydration; (iv) the equilibration of psi(leaf) across the lamina for bagged leaves, and the accuracy of measuring leaves with artificially 'elongated petioles'; (v) the need in psi(leaf) measurements for bagging leaves and high humidity within the chamber; (vi) the need to avoid liquid water on leaf surfaces; (vii) the use of 'pulse' pressurization versus gradual pressurization; and (viii) variation among experimenters in psi(leafPC) determination. Based on our findings we provide a best practice protocol to maximise accuracy, and provide recommendations for ongoing species-specific tests of important assumptions in future studies. ; European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No. 751918-AgroPHYS; Marie Curie Fellowship (FP7-PEOPLE-2013-IOF-624473); ...