scholarly journals Drought-influenced mortality of tree species with different predawn leaf water dynamics in a decade-long study of a central US forest

2015 ◽  
Vol 12 (10) ◽  
pp. 2831-2845 ◽  
Author(s):  
L. Gu ◽  
S. G. Pallardy ◽  
K. P. Hosman ◽  
Y. Sun
Keyword(s):  
Water Potential ◽  
Tree Species ◽  
Tree Mortality ◽  
Leaf Water ◽  
Water Dynamics ◽  
Annual Variations ◽  
Rooting Zone ◽  
Risk Of Death ◽  
Drought Tolerant ◽  
Precipitation Regimes

Abstract. Using decade-long continuous observations of tree mortality and predawn leaf water potential (ψpd) at the Missouri Ozark AmeriFlux (MOFLUX) site, we studied how the mortality of important tree species varied and how such variations may be predicted. Water stress determined inter-annual variations in tree mortality with a time delay of 1 year or more, which was correlated fairly tightly with a number of quantitative predictors formulated based on ψpd and precipitation regimes. Predictors based on temperature and vapor pressure deficit anomalies worked reasonably well, particularly for moderate droughts. The exceptional drought of the year 2012 drastically increased the mortality of all species, including drought-tolerant oaks, in the subsequent year. The drought-influenced tree mortality was related to the species position along the spectrum of ψpd regulation capacity with those in either ends of the spectrum being associated with elevated risk of death. Regardless of species and drought intensity, the ψpd of all species recovered rapidly after sufficiently intense rain events in all droughts. This result, together with a lack of immediate leaf and branch desiccation, suggests an absence of catastrophic hydraulic disconnection in the xylem and that tree death was caused by significant but indirect effects. Species differences in the capacity of regulating ψpd and its temporal integral were magnified under moderate drought intensities but diminished towards wet and dry extremes. Severe droughts may overwhelm the capacity of even drought-tolerant species to maintain differential levels of water potential as the soil becomes exhausted of available water in the rooting zone, thus rendering them more susceptible to death if predisposed by other factors such as age.

scholarly journals Predictors and mechanisms of the drought-influenced mortality of tree species along the isohydric to anisohydic continuum in a decade-long study of a central US temperate forest

2015 ◽  
Vol 12 (2) ◽  
pp. 1285-1325 ◽  
Author(s):  
L. Gu ◽  
S. G. Pallardy ◽  
K. P. Hosman ◽  
Y. Sun
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Tree Species ◽  
Tree Mortality ◽  
Leaf Water ◽  
Extreme Drought ◽  
Positive Temperature ◽  
Drought Intensity ◽  
Predawn Leaf Water Potential ◽  
Annual Variations

Abstract. Using decade-long continuous observations of tree mortality and predawn leaf water potential (ψpd) at the Missouri Ozark AmeriFlux (MOFLUX) site, we studied how the mortality of important tree species varied along the isohydric to anisohydric continuum and how such variations may be predicted. Water stress determined inter-annual variations in tree mortality with a time delay of one year or more, which was predicted by predawn leaf water potential integral (PLWPI), mean effective precipitation interval (a time period with no daily precipitation rates exceeding a threshold) with a daily threshold precipitation at 5 mm day−1 (MEPI5), and precipitation variability index (PVI). Positive temperature anomaly integral (PTAI) and vapor pressure deficit integral (VPDI) also worked reasonably well, particularly for moderate droughts. The extreme drought of the year 2012 drastically increased the mortality of all species in the subsequent year. Regardless of the degree of isohydry and drought intensity, the ψpd of all species recovered rapidly after sufficiently intense rain events. This, together with a lack of immediate leaf and branch desiccation, suggests that hydraulic disconnection in the xylem was absent even during extreme drought and tree death was caused by significant but indirect effects of drought. We also found that species occupying middle positions along the isohydric to anisohydric continuum suffered less mortality than those at either extremes (i.e. extremely isohydric or extremely anisohydric). Finally, our study suggested that species differences in mortality mechanisms can be overwhelmed and masked in extreme droughts and should be examined in a broad range of drought intensity.

scholarly journals Terrestrial Laser Scanning Intensity Captures Diurnal Variation in Leaf Water Potential

2020 ◽  
Author(s):  
Samuli Junttila ◽  
Teemu Hölttä ◽  
Eetu Puttonen ◽  
Masato Katoh ◽  
Mikko Vastaranta ◽  
...  
Keyword(s):  
Diurnal Variation ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Tree Species ◽  
Laser Scanning ◽  
Terrestrial Laser Scanning ◽  
Leaf Water ◽  
Water Dynamics ◽  
Plant Water ◽  
Plant Mortality

Drought-induced plant mortality has increased globally during the last decades and is forecasted to influence global vegetation dynamics. Timely information on plant water dynamics is essential for understanding and anticipating drought-induced plant mortality. The most common metric that has been used for decades for measuring water stress is leaf water potential (ΨL), which is measured destructively. To obtain information on water dynamics from trees and forested landscapes, remote sensing methods have been developed. However, the spatial and temporal resolution of the existing methods have limited our understanding of water dynamics and diurnal variation of ΨL within single trees. Thus, we investigated the capability of terrestrial laser scanning (TLS) intensity in observing diurnal variation in ΨL during a 50 hour monitoring period and aimed to improve understanding on how large part of the diurnal variation in ΨL can be captured using intensity observations. We found that TLS intensity at 905 nm wavelength was able to explain 78% of the variation in ΨL for three trees of two tree species with a root-mean square error of 0.137 MPa. Based on our experiment with three trees, time-series of TLS intensity measurements can be used in detecting changes in ΨL, and thus it is worthwhile to expand the investigations to cover a wider range of tree species and forests and further increase our understanding of plant water dynamics at wider spatial and temporal scales.

scholarly journals Superoxide Dismutase and Stress Tolerance of Four Tomato Cultivars

HortScience ◽  
2004 ◽  
Vol 39 (5) ◽  
pp. 983-986 ◽  
Author(s):  
S.M. Lutfor Rahman ◽  
Wayne A. Mackay ◽  
Eiji Nawata ◽  
Tetsuo Sakuratani ◽  
A.S.M. Mesbah Uddin ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Water Stress ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Protein Concentration ◽  
Leaf Water ◽  
Drought Tolerant ◽  
Fundamental Information ◽  
Initial Reduction ◽  
Tomato Cultivars

Effects of water stress on superoxide dismutase (SOD) activities, changes in protein content, leaf water potential (Ψl) and growth were studied in drought-sensitive Kyokko (KK) and Ratan (RT), and drought-tolerant TM 0126 (TM) and VF-134-1-2 (VF) cultivars of tomato (Lycopersicon esculentum Mill.) in order to obtain fundamental information for breeding drought tolerant cultivars that may be adapted to water stress in many parts of the world. Growth of drought-tolerant TM and VF was greater than that of drought-sensitive KK and RT under water stress conditions. Leaf water potential (Ψl) decreased by water stress treatments in all the cultivars, but the reduction was much more rapid and pronounced in KK and RT than VF and TM. Ψl of stressed cultivars decreased by 30% to 40% compared to the untreated control cultivars. The initial reduction in the range of 20% to 35% was more rapid in KK and RT than TM and VF. SOD activities were increased by water stress in all cultivars. Increase of SOD activities by water stress was much more rapid and pronounced in TM and VF than in KK and RT. Leaf protein concentration was decreased by the water stress treatments in all cultivars evaluated. In KK and RT, much more rapid reductions in protein concentration were observed than in TM and VF. The regression analysis of Ψl and SOD suggest the possibility to using SOD activities as an additional screening criterion for tomato drought tolerance improvement.

scholarly journals Changes in Transpiration and Leaf Water Potential in Douglas-Fir Trees following Douglas-Fir Beetle Attack and Mechanical Girdling

Forests ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1722
Author(s):  
Javier E. Mercado ◽  
Robert T. Walker ◽  
Scott Franklin ◽  
Shannon L. Kay ◽  
Susana Karen Gomez ◽  
...  
Keyword(s):  
Water Potential ◽  
Bark Beetle ◽  
Leaf Water Potential ◽  
Bark Beetles ◽  
Tree Mortality ◽  
Douglas Fir ◽  
Leaf Water ◽  
Lodgepole Pines ◽  
And Control ◽  
Phloem Feeding

Bark beetles and their associated fungi kill trees readily, but we often ignore which organism is the leading cause of tree mortality. While phloem feeding beetles inhibit photosynthate transport, their associated fungi block the tracheids disrupting transpiration. Within the family Pinaceae, knowledge of tree physiological decline following bark beetle and associated fungi colonization is limited to the genus Pinus. Here we investigate the physiological response of Pseudotsuga (P. menziesii) to bark beetles or its fungi. We hypothesized that fungi block water transport in Douglas-fir causing faster mortality than by bark beetle activity alone. We successfully lured Douglas-fir beetle to attack a subset of trees in our experimental area using pheromones and compared Beetle-Killed trees with mechanically Girdled, and Control trees. During spring snowmelt, nine months after treatments were applied, Control, Girdled, and five trees that Survived beetle attack had higher transpiration rates and less negative pre-dawn water potential than five Beetle-Killed trees. Declines in transpiration and leaf water potential in our Beetle-Killed trees occurred much earlier than those in studies of beetle-attacked lodgepole pines, suggesting stronger defensive traits in Douglas-fir. Our data suggest that, as in pines, bark beetle-associated fungi are the leading cause of mortality in Douglas-fir beetle-attacked trees.

Applicability of abscisic acid and (or) proline accumulation as selection criteria for drought tolerance in Nicotiana tabacum

1994 ◽  
Vol 72 (10) ◽  
pp. 1535-1540 ◽  
Author(s):  
L. van Rensburg ◽  
G. H. J. Krüger
Keyword(s):  
Abscisic Acid ◽  
Drought Tolerance ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Proline Accumulation ◽  
Leaf Water ◽  
Cell Wall Elasticity ◽  
Drought Tolerant ◽  
Acid Accumulation ◽  
Selection Parameters

The efficacy of various aspects of abscisic acid and proline accumulation as potential selection parameters for drought tolerance in tobacco was evaluated under controlled conditions. The results indicated that both abscisic acid (though being less pronounced) and proline accumulate rapidly after a distinct threshold leaf water potential value has been reached and that probably because of their higher cell wall elasticity (0.23 and 0.28 MPa for the drought-tolerant cultivars GS46 and Elsoma, respectively, compared with 0.39 and 0.31 MPa for the drought-sensitive cultivars TL33 and CDL28, respectively) these threshold leaf water potential values are reached sooner in drought-tolerant cultivars. However, abscisic acid accumulation precedes proline accumulation in both the drought-tolerant and drought-sensitive cultivars. Proline concentrations increased sharply at a leaf water potential of ca. −1.27 MPa in the drought-tolerant cultivars and at a leaf water potential of ca. −1.50 MPa in the drought-sensitive cultivars. At a leaf water potential of −0.77 MPa the abscisic acid concentrations of all four cultivars were already significantly higher than those of their respective controls and were greater in the drought-tolerant cultivars. The leaf water potential value at which abscisic acid and proline start accumulating rapidly and the accumulated proline end concentrations are recommended as selection parameters for drought tolerance in tobacco. Key words: abscisic acid accumulation, cell-wall elasticity, drought stress, Nicotiana tabacum L., proline accumulation, selection parameters.

RELATIONS BETWEEN RELATIVE TRANSPIRATION AND PREDAWN LEAF WATER POTENTIAL IN DIFFERENT FRUIT TREE SPECIES

1997 ◽  
pp. 423-430 ◽  
Author(s):  
C. Valancogne ◽  
S. Dayau ◽  
M.I. Ferreira Gama ◽  
T. Ameglio ◽  
P. Archer ◽  
...  
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Tree Species ◽  
Fruit Tree ◽  
Leaf Water ◽  
Predawn Leaf Water Potential

DROUGHT RESISTANCE OF Sorghum bicolor. 4. HORMAL CHANGES IN RELATION TO DROUGHT STRESS IN FIELD-GROWN PLANTS

1982 ◽  
Vol 62 (2) ◽  
pp. 317-330 ◽  
Author(s):  
T. KANNANGARA ◽  
R. C. DURLEY ◽  
G. M. SIMPSON ◽  
D. G. STOUT
Keyword(s):  
Drought Stress ◽  
Sorghum Bicolor ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Senescence ◽  
Water Status ◽  
Leaf Water ◽  
Vegetative Stage ◽  
Leaf Water Status ◽  
Drought Tolerant

This study was undertaken to investigate the nature of hormonal changes in relation to drought stress in two cultivars of Sorghum bicolor L. Moench. Two cultivars, M–35 and NK300, were grown in a field plot protected by a rain shelter. Plants in one soil compartment were stressed by withholding water while those in another (controls) were irrigated frequently. Levels of the plant hormones abscisic acid (ABA), phaseic acid (PA) and indole-3-acetic acid (IAA) measured by high-performance liquid chromatography (HPLC) were determined in the youngest leaves of control and stressed plants at intervals throughout the growth cycle. Plant height, senescence, and leaf water status were also determined. Leaf water potential (ψw) and solute potential (ψs) were reduced in both cultivars by drought stress; values for M–35 plants were lower than NK300. Leaf senescence was higher in M–35 plants and was promoted by stress in both cultivars. Cultivar M–35 behaved as a drought-tolerant plant whereas cultivar NK300 behaved more like a drought avoider. ABA levels were higher in M–35 control plants than in corresponding NK300 plants and levels in both cultivars followed seasonal changes in leaf water potential. Under drought stress, ABA levels increased between 1.5 and 2 times in both cultivars with the largest increases occurring during the vegetative stage in M–35 and during the flowering stage for NK300. PA levels in both cultivars were higher in stressed than in control plants. PA levels in M–35 plants were relatively low and constant throughout the life cycle, whereas in NK300, levels were high until shortly before flowering. IAA levels were higher in NK300 than in M–35 plants, particularly during the vegetative stage. Under drought stress, IAA levels were reduced in both cultivars with a more pronounced reduction in NK300. The high level of ABA in the more drought-tolerant cultivar M–35 was associated with low leaf ψw and ψs and high leaf senescence. On the other hand, in the drought avoider, NK300, high levels of IAA and PA were associated with high leaf ψw and ψs. It is concluded that these cultivars, which differ in their response to drought stress, can be distinguished by their leaf hormone levels.

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