scholarly journals Distinct xylem responses to acute vs prolonged drought in pine trees

2020 ◽  
Vol 40 (5) ◽  
pp. 605-620 ◽  
Author(s):  
Marceau Guérin ◽  
Georg von Arx ◽  
Dario Martin-Benito ◽  
Laia Andreu-Hayles ◽  
Kevin L Griffin ◽  
...  
Keyword(s):  
Water Stress ◽  
Soil Drought ◽  
Hydraulic Efficiency ◽  
Atmospheric Moisture ◽  
Water Addition ◽  
Trade Off ◽  
Xylem Structure ◽  
Plant Hydraulics ◽  
Growing Seasons ◽  
Prolonged Drought

Abstract Increasing dryness challenges trees’ ability to maintain water transport to the leaves. Most plant hydraulics models use a static xylem response to water stress. Yet, in reality, lower soil moisture and warmer temperatures during growing seasons feed back onto xylem development. In turn, adjustments to water stress in the newly built xylem influence future physiological responses to droughts. In this study, we investigate the annual variation of anatomical traits in branch xylem in response to different soil and atmospheric moisture conditions and tree stress levels, as indicated by seasonal predawn leaf water potential (ΨL,pd). We used a 6-year field experiment in southwestern USA with three soil water treatments applied to Pinus edulis Engelm trees—ambient, drought (45% rain reduction) and irrigation (15–35% annual water addition). All trees were also subject to a natural 1-year acute drought (soil and atmospheric) that occurred during the experiment. The irrigated trees showed only moderate changes in anatomy-derived hydraulic traits compared with the ambient trees, suggesting a generally stable, well-balanced xylem structure under unstressed conditions. The artificial prolonged soil drought increased hydraulic efficiency but lowered xylem construction costs and decreased tracheid implosion safety ((t/b)2), suggesting that annual adjustments of xylem structure follow a safety–efficiency trade-off. The acute drought plunged hydraulic efficiency across all treatments. The combination of acute and prolonged drought resulted in vulnerable and inefficient new xylem, disrupting the stability of the anatomical trade-off observed in the rest of the years. The xylem hydraulic traits showed no consistent direct link to ΨL,pd. In the future, changes in seasonality of soil and atmospheric moisture are likely to have a critical impact on the ability of P. edulis to acclimate its xylem to warmer climate. Furthermore, the increasing frequency of acute droughts might reduce hydraulic resilience of P. edulis by repeatedly creating vulnerable and less efficient anatomical structure.

A clear trade‐off between leaf hydraulic efficiency and safety in an aridland shrub during regrowth

2021 ◽  
Author(s):  
Guang‐Qian Yao ◽  
Zheng‐Fei Nie ◽  
Yuan‐Yuan Zeng ◽  
Muhammad Waseem ◽  
Md. Mahadi Hasan ◽  
...  
Keyword(s):  
Hydraulic Efficiency ◽  
Trade Off

Red spruce seedling gas exchange in response to elevated CO2, water stress, and soil fertility treatments

1994 ◽  
Vol 24 (5) ◽  
pp. 954-959 ◽  
Author(s):  
L.J. Samuelson ◽  
J.R. Seiler
Keyword(s):  
Water Stress ◽  
Gas Exchange ◽  
Soil Fertility ◽  
Net Photosynthesis ◽  
Growing Season ◽  
Red Spruce ◽  
Fertility Treatment ◽  
Sink Strength ◽  
Growth Enhancement ◽  
Growing Seasons

The interactive influences of ambient (374 μL•L−1) or elevated (713 μL•L−1) CO2, low or high soil fertility, well-watered or water-stressed treatment, and rooting volume on gas exchange and growth were examined in red spruce (Picearubens Sarg.) grown from seed through two growing seasons. Leaf gas exchange throughout two growing seasons and growth after two growing seasons in response to elevated CO2 were independent of soil fertility and water-stress treatments, and rooting volume. During the first growing season, no reduction in leaf photosynthesis of seedlings grown in elevated CO2 compared with seedlings grown in ambient CO2 was observed when measured at the same CO2 concentration. During the second growing season, net photosynthesis was up to 21% lower for elevated CO2-grown seedlings than for ambient CO2-grown seedlings when measured at 358 μL•L−1. Thus, photosynthetic acclimation to growth in elevated CO2 occurred gradually and was not a function of root-sink strength or soil-fertility treatment. However, net photosynthesis of seedlings grown and measured at an elevated CO2 concentration was still over 2 times greater than the photosynthesis of seedlings grown and measured at an ambient CO2 concentration. Growth enhancement by CO2 was maintained, since seedlings grown in elevated CO2 were 40% larger in both size and weight after two growing seasons.

Root water gates and not changes in root structure provide new insights into plant physiological responses to drought, flooding and salinity

2021 ◽  
Author(s):  
Jean-Christophe Domec ◽  
John S King ◽  
Mary J Carmichael ◽  
Anna Treado Overby ◽  
Remi R Wortemann ◽  
...  
Keyword(s):  
Pinus Taeda ◽  
Vapor Pressure Deficit ◽  
Water Movement ◽  
Root Structure ◽  
Transport Capacity ◽  
Transport Efficiency ◽  
Xylem Structure ◽  
Plant Hydraulics ◽  
Whole Plant ◽  
The Impact

Abstract The influence of aquaporin (AQP) activity on plant water movement remains unclear, especially in plants subject to unfavorable conditions. We applied a multitiered approach at a range of plant scales to (i) characterize the resistances controlling water transport under drought, flooding and flooding plus salinity conditions; (ii) quantify the respective effects of AQP activity and xylem structure on root (Kroot), stem (Kstem) and leaf (Kleaf) conductances, and (iii) evaluate the impact of AQP-regulated transport capacity on gas exchange. We found that drought, flooding and flooding-salinity reduced Kroot and root AQP activity in Pinus taeda, whereas Kroot of the flood-tolerant Taxodium distichum did not decline under flooding. The extent of the AQP-control of transport efficiency varied among organs and species, ranging from 35%-55% in Kroot to 10%-30% in Kstem and Kleaf. In response to treatments, AQP-mediated inhibition of Kroot rather than changes in xylem acclimation controlled the fluctuations in Kroot. The reduction in stomatal conductance and its sensitivity to vapor pressure deficit were direct responses to decreased whole-plant conductance triggered by lower Kroot and larger resistance belowground. Our results provide new mechanistic and functional insights on plant hydraulics that are essential to quantifying the influences of future stress on ecosystem function.

Spatial and temporal patterns of lodging in grain sorghum (Sorghum bicolor) in Australia

2020 ◽  
Vol 71 (4) ◽  
pp. 379
Author(s):  
Xuemin Wang ◽  
Emma Mace ◽  
Colleen Hunt ◽  
Alan Cruickshank ◽  
Graeme Hammer ◽  
...  
Keyword(s):  
Water Stress ◽  
Sorghum Bicolor ◽  
Southern Oscillation ◽  
Grain Sorghum ◽  
Spatial And Temporal Patterns ◽  
Lodging Resistance ◽  
Growing Seasons ◽  
Production Environments ◽  
Central Highlands ◽  
Sorghum Production

Grown in water-limited environments, sorghum (Sorghum bicolor (L.) Moench) is often exposed to water deficits of varying extent and timing. One of the impacts of water stress on sorghum production is lodging; however, there has been no published study quantifying the temporal and spatial frequency and severity of lodging in grain sorghum in Australia. In this study, we investigated the frequency and severity of lodging, using a dataset of 83 advanced yield-testing trials of the sorghum pre-breeding program grown in the seven major sorghum-production environments in Australia over 14 summer growing seasons. Lodging occurred in most production regions but with varying frequency and severity. Lodging was significantly greater in regions that were more prone to water stress (e.g. Central Highlands in Queensland) and significantly lower in regions that were less likely to suffer from water stress (e.g. Liverpool Plains in northern New South Wale) compared with the overall average across regions. The severity of lodging also varied across regions, with the most severe lodging (>20%) occurring in Central Highlands and Western Downs in Queensland. In addition, seasonal patterns of lodging frequency and severity were also observed. Over the 14 growing seasons, the frequency of lodging varied from 0% to 100%, with the most severe lodging (>20%) observed in 2005, 2016 and 2017. The Southern Oscillation Index explained 29% of the seasonal variation in lodging frequency. The findings of this study clearly support a link between lodging incidence and water stress across regions and seasons. Our data also showed that although there was a substantial turnover of commercial hybrids during the period of this study, the level of resistance to lodging appeared not to have improved. It is possible that this is due to plant breeders trading off improvements in lodging resistance to increase grain yield.

Diurnal gross photosynthetic patterns and potential seasonal CO2 assimilation in Cladonia stellaris and Cladonia rangiferina

1983 ◽  
Vol 61 (3) ◽  
pp. 642-655 ◽  
Author(s):  
Thomas J. Moser ◽  
Thomas H. Nash III ◽  
Steven O. Link
Keyword(s):  
Photosynthetic Activity ◽  
Growing Season ◽  
Early Morning ◽  
Co2 Assimilation ◽  
Atmospheric Moisture ◽  
Growing Seasons ◽  
Late Evening ◽  
Summer Rain ◽  
Cladonia Rangiferina

The daily, in situ gross photosynthetic patterns of Cladonia stellaris (Opiz.) Pouz. & Vězda. and Cladonia rangiferina (L.) Wigg. were monitored during portions of the 1977, 1978, and 1979 growing seasons at Anaktuvuk Pass, Alaska. Photosynthetic activity in both species closely paralleled atmospheric moisture status, where peak photosynthetic rates were attained during or following sporadic summer rain. In addition, thallus absorption of moisture during extended periods of high atmospheric water vapor content gave rise to short periods of minimal photosynthetic activity. During late evening and early morning hours moistened thalli exhibited minimal or no photosynthetic activity, coinciding with consistent attenuation in solar radiation during these periods. Photosynthetic activity was not homogeneous throughout the thallus. The greatest activity occurred in the apical regions and decreased progressively into the basal regions. The apical 10-mm regions of C. stellaris and C. rangiferina thalli accounted for approximately 50% of their photosynthetic capabilities. The potential gross CO2 assimilation of the apical 10-mm regions over 72 days of the 1978 growing season was estimated at approximately 35 g CO2∙m−2 and 16 g CO2∙m−2 for C. stellaris and C. rangiferina, respectively.

scholarly journals The roles of conduit redundancy and connectivity in xylem hydraulic functions

2020 ◽  
Author(s):  
Assaad Mrad ◽  
Daniel M Johnson ◽  
David M Love ◽  
Jean-Christophe Domec
Keyword(s):  
Graph Theory ◽  
Water Potential ◽  
Percolation Theory ◽  
Water Movement ◽  
Xylem Sap ◽  
Woody Species ◽  
Flowering Plants ◽  
Hydraulic Efficiency ◽  
Trade Off ◽  
Network Characteristics

Wood anatomical traits shape a xylem segment's hydraulic efficiency and embolism spread resistance due to declining water potential. Because xylem sap is in a metastable state, gas embolisms might spread within the sapwood conduits as water potential declines, inhibiting water movement. It has been known for decades that variations in conduit connectivity play a role in altering xylem hydraulics. However, evaluating the precise effect of conduit connectivity on hydraulic efficiency and embolism spread resistance has been elusive. Using graph theory, percolation theory, and computational modeling, we show that increases in conduit connectivity improves resistance to embolism spread in certain flowering plants without compromising hydraulic efficiency. The influence of conduit connectivity might explain in part why the hypothesis of the 'safety-efficiency' trade-off is weak among woody species with different xylem network characteristics. Overall, knowing how xylem network measures influence segment hydraulics is necessary to generalize trends linking anatomy and hydraulic function among woody species.

scholarly journals Water relation features of prunus laurocerasus l. under progressive soil drought stress of soutern coast of the Crimea

2019 ◽  
pp. 28-33
Author(s):  
O. A. Ilnitsky ◽  
A. V. Pashtetsky ◽  
Yu. V. Plugatar ◽  
S. P. Korsakova
Keyword(s):  
Soil Moisture ◽  
Water Stress ◽  
Dark Respiration ◽  
Sharp Decrease ◽  
Stress Factors ◽  
Soil Drought ◽  
Central Vein ◽  
Evergreen Species ◽  
Photosynthetic Gas Exchange ◽  
Prunus Laurocerasus

Study the Ecophysiological reaction Prunus laurocerasus L. effect of progressive soil drought determined optimum thresholds and zones of soil moisture, temperature and light, photosynthesis and transpiration limiting Prunus laurocerasus L. in summer active vegetation on southern coast. Start of development of the plant water stress and inhibition of photosynthesis - the soil moisture reduction to 30% of FC.; Temperature optimum photosynthesis whose exceeding leads to inhibition of the enzyme activity and reduce the rate of photosynthesis - metal temperature 35 C; Growth inhibition, reduction turgor apical young leaves - soil moisture content decrease to 25-20% FC. and Reduced soil moisture to 18% FC and below results in a sharp decrease transpiration rate - 92.3%, visible photosynthesis rate at 95.1% and stomatal conductance by 94.7%. The proportion of the total dark respiration grossphotosynthetic under strong water stress - 78%, in the absence of stress factors - 25-30%; The beginning of the recovery after watering turgor - 1.5-2 hours, the full restoration of the intensity of photosynthetic gas exchange after watering - after 24 hours. Under strong water stress visually noticeable loss of chlorophyll in leaf: Central vein acquired a yellow-green color to leaf- brownish stains. The culture conditions, this leads to loss of decorative qualities of plants. Disclosure mechanisms of functioning of leaves, depending on the environmental impact, provides the basis for the environmental assessment of the physiology of the evergreen species and the possibility of agricultural technology of choice.

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

OENO One ◽  
2017 ◽  
Vol 51 (1) ◽  
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

<p><strong>Aims : </strong>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.</p><p><strong>Methods and results : </strong>Grapevines of the variety <em>Vitis vinifera</em> 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 (d<sup>13</sup>C) in must sugars). Leaf gas exchange (net photosynthesis A and transpiration E), leaf stomatal conductance (gs), specific hydraulic conductivity in petioles (K<sub>petiole</sub>), 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 (WUE<sub>i</sub>, A/gs) increased during the growing season and was greater in water-stressed vines than in well-watered vines (irrigated vines). This rise in WUE<sub>i</sub> was correlated with an increase in d<sup>13</sup>C in must sugars at harvest. Drought led to decreases in K<sub>petiole</sub>, 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.</p><p><strong>Conclusions : </strong>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.</p><p><strong>Significance and impact of the study : </strong>Plant water status constitutes a key factor in leaf gas exchange, canopy water use efficiency, berry composition and wine quality.</p>

Plant hydraulics accentuates the effects of atmospheric moisture stress on transpiration

2020 ◽  
Author(s):  
Alexandra Konings ◽  
Yanlan Liu ◽  
Mukesh Kumar ◽  
Xue Feng ◽  
Gabriel Katul
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Moisture Stress ◽  
Hydraulic Model ◽  
Leaf Water ◽  
Empirical Approach ◽  
Joint Control ◽  
Atmospheric Moisture ◽  
Plant Hydraulics

&lt;p&gt;Transpiration directly links the water, energy and carbon cycles. It is commonly restricted by soil (through soil moisture) and atmospheric (through vapor pressure deficit, VPD) moisture stresses governed by the movement of water through plants, also known as plant hydraulics. These sources of moisture stress are likely to diverge under climate change, with globally enhanced VPD due to increased air temperatures but more variable and uncertain changes in soil moisture. In most Earth system and land surface models, the ET response to each of the two stresses is evaluated through independent empirical relations, while neglecting plant hydraulics. Comparison of these two models is challenged by the difficulty of ensuring any perceived differences are due to the model structure, not an imperfect parametrization. Here, we use a model-data fusion approach applied to long-term ET records collected at 40 sites across a diverse range of biomes to demonstrate that the widely used empirical approach underestimates ET sensitivity to VPD, but compensates by overestimating the sensitivity to soil moisture stress. The bias originates from the joint control of leaf water potential on plant response to soil moisture and VPD stress. To a lesser degree, it also overestimates from increased sensitivity to VPD under dry (low leaf water potential) conditions in the plant hydraulic model. As a result, a hydraulic model captures ET under high-VPD conditions for wide-ranging soil moisture states better than the empirical approach does. Our findings highlight the central role of plant hydraulics in regulating the increasing importance of atmospheric moisture stress on biosphere-atmosphere interactions under elevated temperatures.&lt;/p&gt;

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