New plant hydraulic architecture reproduces impacts of droughts in the Amazon rainforest

The Amazon rainforest has been hit by extreme drought events in recent decades. Thereby, plant hydraulics are essential to better understand the impacts of droughts on single plants and whole forest ecosystems. Plant hydraulic mechanisms such as stomatal closure and leaf water potential are very complex, still posing challenges for current vegetation model development and parameterization. Here, we present the new hydraulic architecture of the Dynamic Global Vegetation Model LPJ-GUESS, accounting for leaf stomatal responses to plant water status and subsequent drought-induced mortality. We show that when applying the model to the Amazon rainforest we can reproduce the observed increasing trend in carbon losses and the decreasing trend in net carbon sink from plot observations over the past two decades. Our model simulations suggest that the increasing historical trend in carbon losses from mortality can be explained by hydraulic failure and associated mortality.The high biodiversity of the Amazon tropical rainforest poses further challenges for process-based models. Here we present an approach to include the diversity of plant responses to drought by simulating 37 individual Plant Functional Types (PFTs) differing in their leaf water potential regulation- and resistance to soil water stress, and provide a simple solution how to cover a wide range of species and species-specific parameters. Future modelling studies should also take species interaction and competition of different hydraulic strategies into account.

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Effect of leaf Water potential on cold tolerance of Coffea arabica L.

Brazilian Archives of Biology and Technology ◽

10.1590/s1516-89132002000600006 ◽

2002 ◽

Vol 45 (4) ◽

pp. 439-443 ◽

Cited By ~ 4

Author(s):

Lázara Pereira Campos Caramori ◽

Paulo Henrique Caramori ◽

João Manetti Filho

Keyword(s):

Water Potential ◽

Leaf Water Potential ◽

Coffea Arabica ◽

Experimental Period ◽

Leaf Water ◽

Regional Variability ◽

Wide Range ◽

Coffee Plants ◽

Coffea Arabica L ◽

Severe Leaf

Young coffee plants from cultivar Mundo Novo of Coffea arabica were grown without irrigation for 32 consecutive days, to evaluate the effect of leaf water potential on damage caused by low temperatures, under controlled conditions. A wide range of leaf water potentials were evaluated, from - 0.45MPa (wet soil) at the beginning of the experimental period, to - 4.8MPa (severe leaf wilting) at the end. Results showed that under moderate water stress, there was a higher frequency of undamaged plants and lower frequency of severely damaged plants. These results help explain part of the regional variability observed after a frost and stress the importance of new studies associating cold and drought tolerance in coffee.

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Evaluation of the hydraulic press for measurement of leaf water potentials in cassava

The Journal of Agricultural Science ◽

10.1017/s0021859600037734 ◽

1983 ◽

Vol 101 (2) ◽

pp. 407-410 ◽

Cited By ~ 1

Author(s):

J. A. Palta

Keyword(s):

Water Potential ◽

Leaf Water Potential ◽

Hydraulic Press ◽

Pressure Chamber ◽

Leaf Water ◽

Moisture Loss ◽

Total Leaf Area ◽

Water Potentials ◽

Wide Range ◽

Poor Relationship

SUMMARYIn the application of the Scholander pressure chamber technique to cassava water relations studies, the leaf water potential measured on central lobules was initially compared with that measured on entire leaves (including petiole). Measurements made using both a Campbell-Brewster hydraulic press and a pressure chamber of the leaf water potential in six different cassava clones were also compared. Although the central lobules showed a greater sensitivity to moisture loss after sampling than entire leaves, their leaf water potential was in close agreement with those measured on the entire leaves (r3 = 0·96). Therefore, for routine and field estimates in cassava, measurements made on the central lobules may be used to avoid the large reduction in total leaf area. The Campbell-Brewster hydraulic press satisfactorily estimated leaf water potential in M.Col. 1684 clone, which had the longest and narrowest lobules, but in other clones the leaf water potential was overestimated at high leaf potential (> -12·5) and underestimated at low water potentials (< -12·5). Over a wide range of leaf water potentials, a poor relationship between leaf water potentials estimated with hydraulic press and with the pressure chamber was observed for cassava because press estimates are influenced by lobule length and lobule width.

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Plant hydraulics accentuates the effects of atmospheric moisture stress on transpiration

10.5194/egusphere-egu2020-8472 ◽

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

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.

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Changes in Diffusive Conductance and Water Potential of Wheat Plants Before and After Anthesis

Functional Plant Biology ◽

10.1071/pp9770075 ◽

1977 ◽

Vol 4 (1) ◽

pp. 75 ◽

Cited By ~ 14

Author(s):

JM Morgan

Keyword(s):

Water Potential ◽

Water Deficit ◽

Leaf Water Potential ◽

Leaf Water ◽

Wide Range ◽

Before And After ◽

Relative Water ◽

Complete Failure ◽

Two Phases ◽

The Relationship

The relationships between stomatal conductance and leaf water potential, ΨL, of wheat plants during drying under controlled conditions showed three phases: (1) no apparent effect until ΨL reached about - 1.8 J g-1; (2) increasing closure as ΨL decreased to about - 3 J g-1; and (3) complete failure to open at lower ΨL values. At any given water potential in the first two phases, the stomata were always more open during the post-anthesis stage than during the pre-anthesis stage. Although the relationship between leaf water potential and relative water content differed with growth stage, this was not important in the overall plant response to a water deficit. Over a wide range of ΨL, the conductance of the adaxial surface was less variable and more sensitive than that of the abaxial surface. The ratio of these conductances was very variable and followed no discernible pattern. The water potential of spikelets was appreciably higher than that of flag leaves, especially at low values of the latter. Both organs died at about the same water potential (about -4 J g-1); hence, spikelets survived longer periods of water deficit than leaves. These responses are discussed in respect of sensitivity of grain yield to the stage of growth at which a water deficit is experienced and to the phenomenon of spikelet death. Differences between three cultivars examined were small.

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Comparisons between Press and Pressure Chamber Techniques for Measuring Leaf Water Potential

Experimental Agriculture ◽

10.1017/s001447970001125x ◽

1981 ◽

Vol 17 (1) ◽

pp. 75-84 ◽

Cited By ~ 9

Author(s):

T. M. Yegappan ◽

B. J. Mainstone

Keyword(s):

Water Potential ◽

Leaf Water Potential ◽

Elaeis Guineensis ◽

Water Status ◽

High Water ◽

Hydraulic Press ◽

Pressure Chamber ◽

Leaf Water ◽

Wide Range ◽

The Press

SUMMARYA hydraulic press (the J-14) was compared with a Scholander pressure chamber to measure leaf water potential in Theobroma cacao, Gliricidia maculata, Cajanus cajan and Elaeis guineensis. Although the press satisfactorily estimated water status in soft, unhardened leaves of T. cacao, G. maculata and C. cajan at high water potential, it underestimated water status in hardened leaves of T. cacao. Satisfactory estimates were obtained at low water potential for hardened leaves of T. cacao but not for the others. There was a poor relation between readings of the two instruments for E. guineensis over a wide range of water potentials because press readings appeared to be influenced by leaf structure.

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327 LEAF WATER POTENTIAL, RELATIVE WATER CONTENT AND GAS EXCHANGE OF STRAWBERRY LEAVES IN RESPONSE TO WATE.R STRESS

HortScience ◽

10.21273/hortsci.29.5.477d ◽

1994 ◽

Vol 29 (5) ◽

pp. 477d-477

Author(s):

Chuhe Chen ◽

J. Scott Cameron ◽

Ann Marie VanDerZanden

Keyword(s):

Gas Exchange ◽

Water Potential ◽

Water Content ◽

Leaf Water Potential ◽

Relative Water Content ◽

Leaf Age ◽

Leaf Water ◽

Derivative Spectra ◽

Wide Range ◽

Relative Water

Leaf water potential (LWP). relative water content (RWC), gas exchange rates and 4th-derivative spectra were measured in water-stressed and normally Irrigated plank of Totem' strawberry (Fragaria × ananassa) grown in a growth chamber. CO2 assimilation rate (A) dropped sharply when LWP decreased from -0.5 to -1.2 MPa and almost ceased as LWP fell below -1.5 MPa. There was a significant but more gradual decline of A as RWC decreased form 90% to 55%. An exponential relationship with A was observed across a wide range of LWP and RWC (Rz= 0.64, 0.86, respectively). LWP was more closely related with transpiration and leaf and stomatal conductances than with A and water use efficiency. RWC was highly correlated with all gas exchange parameters. Under moderate water stress, younger leaves maintain higher RWC and A than older leaves. There was no relationship between LWP and leaf age. RWC and A were both negatively correlated with peak amplitudes of Ca 684 and Ca 697 and positively correlated with Ca 693 in their 4th-derivative spectra of chlorophyll. LWP had a negative correlation with Cb 640.

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