Persistent drought monitoring using a microfluidic-printed electro-mechanical sensor of stomata in planta

This work reports on experimental evidence for the role of ion-mediated changes of xylem hydraulic conductivity in the functional response of Solanum lycopersicum L. cv. Naomi to moderate salinity levels. Measurements were performed in fully developed 12-week-old plants grown in half-strength Hoagland solution (control, C-plants) or in the same solution added with 35 mM NaCl (NaCl-plants). NaCl-plants produced a significantly less but heavier leaves and fruits but had similar gas-exchange rates as control plants. Moreover, NaCl-plants showed higher vessel multiple fraction (FVM) than control plants. Xylem sap potassium and sodium concentrations were significantly higher in NaCl-plants than in control plants. When stems were perfused with 10 mM NaCl or KCl, the hydraulic conductance of NaCl plants was nearly 1.5 times higher than in control plants. Accordingly, stem hydraulic conductance measured in planta was higher in NaCl- than in control plants. Our data suggest that tomato plants grown under moderate salinity upregulate xylem sap [Na+] and [K+], as well as sensitivity of xylem hydraulics to sap ionic content, thus, increasing water transport capacity.

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The interplay between irrigation and fruiting on branch growth and mortality, gas exchange and water relations of coffee trees

Tree Physiology ◽

10.1093/treephys/tpaa116 ◽

2020 ◽

Author(s):

Wellington L Almeida ◽

Rodrigo T Ávila ◽

Junior P Pérez-Molina ◽

Marcela L Barbosa ◽

Dinorah M S Marçal ◽

...

Keyword(s):

Stomatal Conductance ◽

Gas Exchange ◽

Stomatal Density ◽

Leaf Gas Exchange ◽

Water Status ◽

Co2 Concentration ◽

Plant Hydraulics ◽

Branch Growth ◽

Source To Sink ◽

Leaf Transpiration

Abstract The overall coordination between gas exchanges and plant hydraulics may be affected by soil water availability and source-to-sink relationships. Here we evaluated how branch growth and mortality, leaf gas exchange and metabolism are affected in coffee (Coffea arabica L.) trees by drought and fruiting. Field-grown plants were irrigated or not, and maintained with full or no fruit load. Under mild water deficit, irrigation per se did not significantly impact growth but markedly reduced branch mortality in fruiting trees, despite similar leaf assimilate pools and water status. Fruiting increased net photosynthetic rate in parallel with an enhanced stomatal conductance, particularly in irrigated plants. Mesophyll conductance and maximum RuBisCO carboxylation rate remained unchanged across treatments. The increased stomatal conductance in fruiting trees over nonfruiting ones was unrelated to internal CO2 concentration, foliar abscisic acid (ABA) levels or differential ABA sensitivity. However, stomatal conductance was associated with higher stomatal density, lower stomatal sensitivity to vapor pressure deficit, and higher leaf hydraulic conductance and capacitance. Increased leaf transpiration rate in fruiting trees was supported by coordinated alterations in plant hydraulics, which explained the maintenance of plant water status. Finally, by preventing branch mortality, irrigation can mitigate biennial production fluctuations and improve the sustainability of coffee plantations.

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The influence of water stress on plant hydraulics, gas exchange, berry composition and quality of Pinot Noir wines in Switzerland

OENO One ◽

10.20870/oeno-one.2017.51.1.1314 ◽

2017 ◽

Vol 51 (1) ◽

Cited By ~ 10

Author(s):

Vivian Zufferey ◽

Jean-Laurent Spring ◽

Thibaut Verdenal ◽

Agnès Dienes ◽

Sandrine Belcher ◽

...

Keyword(s):

Water Stress ◽

Gas Exchange ◽

Leaf Gas Exchange ◽

Water Status ◽

Growing Season ◽

Pinot Noir ◽

Wine Quality ◽

Plant Hydraulics ◽

Berry Composition

Aims : The aims of this study were to investigate the physiological behavior (plant hydraulics, gas exchange) of the cultivar Pinot Noir in the field under progressively increasing conditions of water stress and analyze the effects of drought on grape and wine quality.Methods and results : Grapevines of the variety Vitis vinifera L. cv. Pinot Noir (clone 9-18, grafted onto 5BB) were subjected to different water regimes (irrigation treatments) over the growing season. Physiological indicators were used to monitor plant water status (leaf and stem water potentials and relative carbon isotope composition (d13C) in must sugars). Leaf gas exchange (net photosynthesis A and transpiration E), leaf stomatal conductance (gs), specific hydraulic conductivity in petioles (Kpetiole), yield components, berry composition at harvest, and organoleptic quality of wines were analyzed over a 7-year period, between 2009 and 2015, under relatively dry conditions in the canton of Wallis, Switzerland. A progressively increasing water deficit, observed throughout the season, reduced the leaf gas exchange (A and E) and gs in non-irrigated vines. The intrinsic water use efficiency (WUEi, A/gs) increased during the growing season and was greater in water-stressed vines than in well-watered vines (irrigated vines). This rise in WUEi was correlated with an increase in d13C in must sugars at harvest. Drought led to decreases in Kpetiole, E and sap flow in stems. A decrease in vine plant vigor was observed in vines that had been subjected to water deficits year after year. Moderate water stress during ripening favored sugar accumulation in berries and caused a reduction in total acidic and malic contents in must and available nitrogen content (YAN). Wines produced from water-stressed vines had a deeper color and were richer in anthocyanins and phenol compounds compared with wines from well-watered vines with no water stress. The vine water status greatly influenced the organoleptic quality of the resulting wines. Wines made from non-irrigated vines with a water deficit presented more structure and higher-quality tannins. They were also judged to be more full-bodied and with blended tannins than those made from irrigated vines.Conclusions : Grape ripening and resulting Pinot Noir wines were found to be largely dependent on the water supply conditions of the vines during the growing season, which influenced gas exchange and plant hydraulics.Significance and impact of the study : Plant water status constitutes a key factor in leaf gas exchange, canopy water use efficiency, berry composition and wine quality.

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On which timescale(s) do optimal adjustments to vegetation function confer resilience? A case study in South-Eastern Australia

10.5194/egusphere-egu21-14908 ◽

2021 ◽

Author(s):

Manon Sabot ◽

Martin De Kauwe ◽

Andy Pitman ◽

Belinda Medlyn ◽

Silvia Caldararu ◽

...

Keyword(s):

Water Stress ◽

Gas Exchange ◽

Optimality Theory ◽

Land Surface ◽

Future Climate Change ◽

Leaf Biomass ◽

Plant Hydraulics ◽

South Eastern ◽

Eastern Australia ◽

South Eastern Australia

Droughts have been implicated as the driver behind recent vegetation die-off across a variety of hydroclimates and are projected to drive greater mortality under future climate change. Predicting ecosystem resilience to future drought requires a predictive capacity, which is currently lacking in state-of-the-art land surface models (LSMs) that rely on simplified empirical relationships to represent the impacts of water stress on vegetation. Novel approaches that optimise stomatal conductance with respect to plant photosynthetic and hydraulic functions have been shown to reduce the biases of LSM gas exchange predictions during drought. These approaches also offer a pathway to further develop mechanistic optimality theory, e.g. pertaining to leaf drought deciduousness. But on what timescale(s) does vegetation function adjust to maximise resource investment? We explore the following timescales of optimality within a simple LSM: (i) instantaneous (regulating canopy gas exchange); (ii) monthly (regulating the investment of nitrogen in photosynthetic capacity); and (iii) seasonal to annual (water stress legacies on plant hydraulics). We use observations from a temperate woodland in South-Eastern Australia to test which optimisation timescales and processes are best supported and whether competing timescales can operate together, both under well-watered conditions and during a severe multi-year drought, and from the leaf-scale to the ecosystem-scale. The insights gained help us characterize how adjoined allocation processes, like leaf biomass adjustment, relate to leaf carbon uptake and plant water status through time (e.g. leaves can be shed to mitigate drought stress or built from structural storage pools when water is not limiting), therefore conferring additional resilience.

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Functional Status of Xylem Through Time

Annual Review of Plant Biology ◽

10.1146/annurev-arplant-050718-100455 ◽

2019 ◽

Vol 70 (1) ◽

pp. 407-433 ◽

Cited By ~ 13

Author(s):

Craig R. Brodersen ◽

Adam B. Roddy ◽

Jay W. Wason ◽

Andrew J. McElrone

Keyword(s):

Functional Status ◽

Water Transport ◽

Vascular Plants ◽

Woody Species ◽

In Planta ◽

Long Distance ◽

Plant Hydraulics ◽

Physiological Processes ◽

Plant Water Use ◽

Terrestrial Water

Water transport in vascular plants represents a critical component of terrestrial water cycles and supplies the water needed for the exchange of CO2 in the atmosphere for photosynthesis. Yet, many fundamental principles of water transport are difficult to assess given the scale and location of plant xylem. Here we review the mechanistic principles that underpin long-distance water transport in vascular plants, with a focus on woody species. We also discuss the recent development of noninvasive tools to study the functional status of xylem networks in planta. Limitations of current methods to detect drought-induced xylem blockages (e.g., embolisms) and quantify corresponding declines in sap flow, and the coordination of hydraulic dysfunction with other physiological processes are assessed. Future avenues of research focused on cross-validation of plant hydraulics methods are discussed, as well as a proposed fundamental shift in the theory and methodology used to characterize and measure plant water use.

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