Sap flow, leaf-level gas exchange and spectral responses to drought in Pinus sylvestris, Pinus pinea and Pinus halepensis

Aleppo pine (Pinus halepensis Mill.) is widespread in most countries of the Mediterranean area. In Greece, Aleppo pine forms natural stands of high economic and ecological importance. Understanding the species’ ecophysiological traits is important in our efforts to predict its responses to ongoing climate variability and change. Therefore, the aim of this study was to assess the seasonal dynamic in Aleppo pine gas exchange and water balance on the leaf and canopy levels in response to the intra-annual variability in the abiotic environment. Specifically, we assessed needle gas exchange, water potential and δ13C ratio, as well as tree sap flow and canopy conductance in adult trees of a mature near-coastal semi-arid Aleppo pine ecosystem, over two consecutive years differing in climatic conditions, the latter being less xerothermic. Maximum photosynthesis (Amax), stomatal conductance (gs), sap flow per unit leaf area (Ql), and canopy conductance (Gs) peaked in early spring, before the start of the summer season. During summer drought, the investigated parameters were negatively affected by the increasing potential evapotranspiration (PET) rate and vapor pressure deficit (VPD). Aleppo pine displayed a water-saving, drought avoidance (isohydric) strategy via stomatal control in response to drought. The species benefited from periods of high available soil water, during the autumn and winter months, when other environmental factors were not limiting. Then, on the leaf level, air temperature had a significant effect on Amax, while on the canopy level, VPD and net radiation affected Ql. Our study demonstrates the plasticity of adult Aleppo pine in this forest ecosystem in response to the concurrent environmental conditions. These findings are important in our efforts to predict and forecast responses of the species to projected climate variability and change in the region.

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Heatwave frequency and seedling death alter stress-specific emissions of volatile organic compounds in Aleppo pine

Oecologia ◽

10.1007/s00442-021-04905-y ◽

2021 ◽

Author(s):

Benjamin Birami ◽

Ines Bamberger ◽

Andrea Ghirardo ◽

Rüdiger Grote ◽

Almut Arneth ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Gas Exchange ◽

Organic Compounds ◽

Stress Responses ◽

Methyl Salicylate ◽

Environmental Changes ◽

Pinus Halepensis ◽

Dark Respiration ◽

Seedling Mortality ◽

Volatile Organic

AbstractBiogenic volatile organic compounds (BVOC) play important roles in plant stress responses and can serve as stress indicators. While the impacts of gradual environmental changes on BVOCs have been studied extensively, insights in emission responses to repeated stress and recovery are widely absent. Therefore, we studied the dynamics of shoot gas exchange and BVOC emissions in Pinus halepensis seedlings during an induced moderate drought, two four-day-long heatwaves, and the combination of drought and heatwaves. We found clear stress-specific responses of BVOC emissions. Reductions in acetone emissions with declining soil water content and transpiration stood out as a clear drought indicator. All other measured BVOC emissions responded exponentially to rising temperatures during heat stress (maximum of 43 °C), but monoterpenes and methyl salicylate showed a reduced temperature sensitivity during the second heatwave. We found that these decreases in monoterpene emissions between heatwaves were not reflected by similar declines in their internal storage pools. Because stress intensity was extremely severe, most of the seedlings in the heat-drought treatment died at the end of the second heatwave (dark respiration ceased). Interestingly, BVOC emissions (methanol, monoterpenes, methyl salicylate, and acetaldehyde) differed between dying and surviving seedlings, already well before indications of a reduced vitality became visible in gas exchange dynamics. In summary, we could clearly show that the dynamics of BVOC emissions are sensitive to stress type, stress frequency, and stress severity. Moreover, we found indications that stress-induced seedling mortality was preceded by altered methanol, monoterpene, and acetaldehyde emission dynamics.

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Impact of Altitudinal Variation on the Phytochemical Profile, Anthelmintic and Antimicrobial Activity of Two Pinus Species

Molecules ◽

10.3390/molecules26113170 ◽

2021 ◽

Vol 26 (11) ◽

pp. 3170

Author(s):

Wafaa M. Elkady ◽

Mariam H. Gonaid ◽

Miriam F. Yousif ◽

Mahmoud El-Sayed ◽

Hind A. N. Omar

Keyword(s):

Antimicrobial Activity ◽

Essential Oils ◽

Pinus Halepensis ◽

Biological Activities ◽

Anthelmintic Activity ◽

Antimicrobial Activities ◽

Pinus Pinea ◽

Active Components ◽

Pinus Species ◽

Bacteria And Fungi

Active components from natural sources are the current focus in most pharmacological research to provide new therapeutic agents for clinical use. Essential oils from the Pinus species have been traditionally used in medicine. This study aimed to investigate the chemical profile of two Pinus species, Pinus halepensis L. and Pinus pinea Mill, from different altitudes in Libya and study the effect of environmental conditions on the biological activities of essential oils. A clevenger apparatus was used to prepare the essential oils by hydrodistillation. Analyses were done using GC/MS. Anthelmintic and antimicrobial activities were tested against the earthworm Allolobophora caliginosa, gram-positive bacteria, gram-negative bacteria, and fungi. Different chemical profiles were observed among all tested essential oils, and terpenes were the most dominant class. All studied essential oils from the Pinus species exhibited a remarkable anthelmintic activity compared to the standard piperazine citrate drug. Pinus halepensis from both altitudes showed broad-spectrum antimicrobial activity against all tested microorganisms, while Pinus pinea was effective against only Escherichia coli. From these findings, one can conclude that there are variations between studied species. The essential oil compositions are affected by environmental factors, which consequently affect the anthelmintic and antimicrobial activity.

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A reporting format for leaf-level gas exchange data and metadata

Ecological Informatics ◽

10.1016/j.ecoinf.2021.101232 ◽

2021 ◽

Vol 61 ◽

pp. 101232

Author(s):

Kim S. Ely ◽

Alistair Rogers ◽

Deborah A. Agarwal ◽

Elizabeth A. Ainsworth ◽

Loren P. Albert ◽

...

Keyword(s):

Gas Exchange ◽

Leaf Level ◽

Exchange Data

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Water Deficit Modulates the CO2 Fertilization Effect on Plant Gas Exchange and Leaf-Level Water Use Efficiency: A Meta-Analysis

Frontiers in Plant Science ◽

10.3389/fpls.2021.775477 ◽

2021 ◽

Vol 12 ◽

Author(s):

Fei Li ◽

Dagang Guo ◽

Xiaodong Gao ◽

Xining Zhao

Keyword(s):

Gas Exchange ◽

Water Use Efficiency ◽

Soil Water ◽

Water Deficit ◽

Water Use ◽

Future Climate Change ◽

Leaf Level ◽

Fertilization Effect ◽

Use Efficiency ◽

Stimulation Of

Elevated atmospheric CO2 concentrations ([eCO2]) and soil water deficits significantly influence gas exchange in plant leaves, affecting the carbon-water cycle in terrestrial ecosystems. However, it remains unclear how the soil water deficit modulates the plant CO2 fertilization effect, especially for gas exchange and leaf-level water use efficiency (WUE). Here, we synthesized a comprehensive dataset including 554 observations from 54 individual studies and quantified the responses for leaf gas exchange induced by e[CO2] under water deficit. Moreover, we investigated the contribution of plant net photosynthesis rate (Pn) and transpiration rates (Tr) toward WUE in water deficit conditions and e[CO2] using graphical vector analysis (GVA). In summary, e[CO2] significantly increased Pn and WUE by 11.9 and 29.3% under well-watered conditions, respectively, whereas the interaction of water deficit and e[CO2] slightly decreased Pn by 8.3%. Plants grown under light in an open environment were stimulated to a greater degree compared with plants grown under a lamp in a closed environment. Meanwhile, water deficit reduced Pn by 40.5 and 37.8%, while increasing WUE by 24.5 and 21.5% under ambient CO2 concentration (a[CO2]) and e[CO2], respectively. The e[CO2]-induced stimulation of WUE was attributed to the common effect of Pn and Tr, whereas a water deficit induced increase in WUE was linked to the decrease in Tr. These results suggested that water deficit lowered the stimulation of e[CO2] induced in plants. Therefore, fumigation conditions that closely mimic field conditions and multi-factorial experiments such as water availability are needed to predict the response of plants to future climate change.

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Modification of a gas exchange system to measure active and passive chlorophyll fluorescence simultaneously under field conditions

AoB Plants ◽

10.1093/aobpla/plaa066 ◽

2020 ◽

Author(s):

Eliot W Meeker ◽

Troy S Magney ◽

Nicolas Bambach ◽

Mina Momayyezi ◽

Andrew J McElrone

Keyword(s):

Chlorophyll Fluorescence ◽

Steady State ◽

Gas Exchange ◽

Near Infrared ◽

Pulse Amplitude ◽

Bottom Plate ◽

Pam Fluorometer ◽

Promising Tool ◽

Leaf Level ◽

Gas Exchange System

Abstract Solar-induced fluorescence (SIF) is a promising tool to estimate photosynthesis across scales; however, there has been limited research done at the leaf-level to investigate the relationship between SIF and photosynthesis. To help bridge this gap, a LI-COR LI-6800 gas exchange instrument was modified with a visible-near-infrared (VIS-NIR) spectrometer to measure active and passive fluorescence simultaneously. The system was adapted by drilling a hole into the bottom plate of the leaf chamber and inserting a fiber-optic to measure passive steady-state fluorescence (Ft,λ, analogous to SIF) from the abaxial surface of a leaf. This new modification can concurrently measure gas exchange, passive fluorescence, and active fluorescence over the same leaf area and will allow researchers to measure leaf-level Ft,λ in the field to validate tower-based and satellite measurements. To test the modified instrument, measurements were performed on leaves of well-watered and water stressed walnut plants at three light-levels and a constant air temperature. Measurements on these same plants were also conducted using a similarly modified Walz GFS-3000 gas exchange instrument to compare results. We found a positive linear correlation between Ft,λ measurements from the modified LI-6800 and GFS-3000 instruments. We also report a positive linear relationship between Ft,λ and normalized steady-state chlorophyll fluorescence (Ft/Fo) from the pulse-amplitude modulation (PAM) fluorometer of the LI-6800 system. Accordingly, this modification will inform the link between spectrally resolved Ft,λ and gas-exchange – leading to improved interpretation of how remotely sensed SIF tracks changes in the light reactions of photosynthesis.

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Partial rootzone drying improves almond tree leaf-level water use efficiency and afternoon water status compared with regulated deficit irrigation

Functional Plant Biology ◽

10.1071/fp10247 ◽

2011 ◽

Vol 38 (5) ◽

pp. 372 ◽

Cited By ~ 24

Author(s):

Gregorio Egea ◽

Ian C. Dodd ◽

María M. González-Real ◽

Rafael Domingo ◽

Alain Baille

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Leaf Gas Exchange ◽

Water Status ◽

Stem Water Potential ◽

Regulated Deficit Irrigation ◽

Leaf Level ◽

Use Efficiency ◽

Stem Water ◽

Partial Rootzone Drying

To determine whether partial rootzone drying (PRD) optimised leaf gas exchange and soil–plant water relations in almond (Prunus dulcis (Mill.) D.A. Webb) compared with regulated deficit irrigation (RDI), a 2 year trial was conducted on field-grown trees in a semiarid climate. Five irrigation treatments were established: full irrigation (FI) where the trees were irrigated at 100% of the standard crop evapotranspiration (ETc); three PRD treatments (PRD70, PRD50 and PRD30) that applied 70, 50 and 30% ETc, respectively; and a commercially practiced RDI treatment that applied 50% ETc during the kernel-filling stage and 100% ETc during the remainder of the growth season. Measurements of volumetric soil moisture content in the soil profile (0–100 cm), predawn leaf water potential (Ψpd), midday stem water potential (Ψms), midday leaf gas exchange and trunk diameter fluctuations (TDF) were made during two growing seasons. The diurnal patterns of leaf gas exchange and stem water potential (Ψs) were appraised during the kernel-filling stage in all irrigation regimes. When tree water relations were assessed at solar noon, PRD did not show differences in either leaf gas exchange or tree water status compared with RDI. At similar average soil moisture status (adjudged by similar Ψpd), PRD50 trees had higher water status than RDI trees in the afternoon, as confirmed by Ψs and TDF. Although irrigation placement showed no effects on diurnal stomatal regulation, diurnal leaf net photosynthesis (Al) was substantially less limited in PRD50 than in RDI trees, indicating that PRD improved leaf-level water use efficiency.

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The Annual Rhythm of Activity of the Lateral Meristems (Cambium and Phellogen) in Pinus Halepensis Mill. and Pinus Pinea L.

IAWA Journal ◽

10.1163/22941932-90000413 ◽

1984 ◽

Vol 5 (4) ◽

pp. 263-274 ◽

Cited By ~ 36

Author(s):

Nili Liphschitz ◽

S. Lev-Yadun ◽

E. Rosen ◽

Y. Waisel

Keyword(s):

Mediterranean Climate ◽

Pinus Halepensis ◽

Rest Period ◽

Pinus Pinea ◽

Winter Dormancy ◽

Natural Conditions ◽

Quiescent Period ◽

Short Period ◽

Climate Patterns ◽

Almost All

The annual rhythms of cambial and phellogen activity in Pinus halepensis and P pinea were investigated. Under natural conditions the cambium of P halepensis begins its activity in autumn, enters a quiescent period during midwinter, resurnes activity towards spring and enters a second rest period in summer. The ring border is formed during summer. Irrigated plants growing outdoors were active almost all the year round.The cambium of P pinea is active between April and November and enters a true winter dormancy.The duration of xylem production exceeded that of the phloem. More xylem than phloem cells were formed. The phellogen was active during a short period only.Pinus halepensis seems to follow the Mediterranean climate patterns whereas P pinea follows the pattern of a colder climate.

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Variability in hydraulic architecture and gas exchange of common bean (Phaseolus vulgaris) cultivars under well-watered conditions: interactions with leaf size

Functional Plant Biology ◽

10.1071/pp98137 ◽

1999 ◽

Vol 26 (2) ◽

pp. 115 ◽

Cited By ~ 17

Author(s):

Maurizio Mencuccini ◽

Jonathan Comstock

Keyword(s):

Gas Exchange ◽

Exchange Rates ◽

Common Bean ◽

Water Loss ◽

Leaf Size ◽

Hydraulic Conductance ◽

Hydraulic Architecture ◽

Greenhouse Study ◽

Whole Plant ◽

Leaf Level

In a greenhouse study, 12 common bean cultivars from a wide geographical range were compared for their morphological, gas exchange and hydraulic architecture characters. Cultivars bred for cultivation in hot and dry regions had significantly smaller leaves and crowns, but higher stomatal conductances and transpiration rates per unit of leaf area. Short-term variability in gas exchange rates was confirmed using leaf carbon isotope discrimination. A literature survey showed that, although previously unnoticed, the strong inverse coupling between leaf size and gas exchange rates was present in three other studies using the same set of cultivars. Several measures of ‘leaf-specific hydraulic conductance’ (i.e. for the whole plant and for different parts of the xylem pathway) were also linearly related to rates of water loss, suggesting that the coupling between leaf size and gas exchange was mediated by a hydraulic mechanism. It is possible that breeding for high production in hot regions has exerted a selection pressure to increase leaf-level gas exchange rates and leaf cooling. The associated reductions in leaf size may be explained by the need to maintain equilibrium between whole-plant water loss and liquid-phase hydraulic conductance.

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