Xylem cavitation, leaf growth and leaf water potential in Eucalyptusglobulus clones under well-watered and drought conditions

2003 ◽  
Vol 30 (8) ◽  
pp. 891 ◽  
Author(s):  
Pilar Pita ◽  
Antonio Gascó ◽  
José A. Pardos
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Growth ◽  
Field Trials ◽  
Leaf Water ◽  
Xylem Cavitation ◽  
Predawn Leaf Water Potential ◽  
Drought Conditions ◽  
Leaf Shedding ◽  
Maximum Permeability

Leaf growth, predawn leaf water potential (Ψpd), evapotranspiration, stem maximum permeability, and its percentage loss of hydraulic conductivity (PLC) were measured in rooted cuttings of selected clones of Eucalyptus globulus Labill. subjected to well-watered and drought conditions. Drought significantly reduced evapotranspiration, leaf growth and maximum permeability. E. globulus clones lost up to 70% of conductivity at values of Ψpd less negative than –1 MPa. PLC values higher than 85% could not be measured without causing leaf shedding. The coefficient related to the slope of the vulnerability curves ranged from 1.52–2.23. The lowest value was measured in the most drought-resistant clone, as estimated from field trials. Plants from this clone displayed higher drought-induced reductions in maximum permeability than plants from other clones, had significantly smaller leaves and maintained higher values of predawn leaf water potential as soil water content (SWC) declined.

Photosynthesis Response of Sunlit and Shade Pepper (Capsicum annuum) Leaves at Different Positions in the Canopy Under Two Water Regimes

1994 ◽  
Vol 21 (3) ◽  
pp. 377 ◽  
Author(s):  
A Alvino ◽  
M Centritto ◽  
FD Lorenzi
Keyword(s):  
Water Potential ◽  
Capsicum Annuum ◽  
Leaf Water Potential ◽  
Co2 Exchange ◽  
Leaf Water ◽  
Predawn Leaf Water Potential ◽  
Water Regimes ◽  
Water Potentials ◽  
Sun And Shade ◽  
Shade Leaves

Pepper (Capsicum annuum L.) plants were grown in 1 m2 lysimeters under two different water regimes in order to investigate differences in the spatial arrangements of the leaves and to relate this to daily assimilation rates of leaves of the canopy. The control regime (well-watered (W) treatment) was irrigated whenever the accumulated 'A' pan evaporation reached 4 cm, whereas the water-stressed (S) treatment was watered whenever the predawn leaf water potential fell below -1 MPa. During the growing cycle, equal numbers of sun and shade leaves were chosen from the apical, middle and basal parts of the canopy, corresponding to groups of leaves of increasing age. The CO2 exchange rate (CER) was measured at 0830, 1230 and 1530 hours on 8 days along the crop cycle, on leaves in their natural inclination and orientation. Leaf water potentials were measured on apical leaves before dawn and concurrently with gas exchange measurements. Control plants maintained predawn leaf water potential at -0.3 MPa, but S plants reached values lower than -1.2 MPa. Midday leaf water potentials were about twice as low in the S plants as in the controls. Water stress reduced LA1 during the period of crop growth, and dry matter production at harvest. Stressed apical leaves appeared to reduce stress by changing their inclination. They were paraheliotropic around midday and diaheliotropic at 0830 and 1530 hours. The CER values of the S treatment were significantly lower than those of the W treatment in apical and middle leaves, whereas the CER of basal leaves did not differ in either treatments. In the S treatment, reduction in the CER values of sunlit apical leaves was more evident in the afternoon than at midday or early in the morning, whereas basal leaves were less affected by water than basal stress leaves if sunlit, and negligibly in shaded conditions.

Predicting Predawn Leaf Water Potential up to Seven Days Using Machine Learning

2021 ◽  
pp. 39-50
Author(s):  
Ahmed A. Fares ◽  
Fabio Vasconcelos ◽  
Joao Mendes-Moreira ◽  
Carlos Ferreira
Keyword(s):  
Machine Learning ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Predawn Leaf Water Potential

The validity of predawn leaf water potential as an irrigation-timing indicator for field-grown wheat in northern Syria

2006 ◽  
Vol 82 (1-2) ◽  
pp. 223-236 ◽  
Author(s):  
Takahiro Sato ◽  
Osman S. Abdalla ◽  
Theib Y. Oweis ◽  
Tetsuo Sakuratani
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Leaf Water ◽  
Predawn Leaf Water Potential

scholarly journals Environmental and physiological control of water flux through Pinuscontorta

1980 ◽  
Vol 10 (1) ◽  
pp. 82-91 ◽  
Author(s):  
Steven W. Running
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Potential Temperature ◽  
Water Flux ◽  
Soil Water Potential ◽  
Leaf Conductance ◽  
Leaf Water ◽  
Physiological Control ◽  
Indirect Measure ◽  
Predawn Leaf Water Potential

This study reports measurements of leaf conductance, leaf water potential, temperature, humidity, and radiation collected on a stand of Pinuscontorta Dougl. ex Loud, lodgepole pine throughout a growing season at the Fraser Experimental Forest in central Colorado, U.S.A. The daily range of leaf conductances decreased 10-fold from June through August. A high correlation (R2 = 0.75) was found between predawn leaf water potential and morning maximum leaf conductance. Low atmospheric humidity significantly decreased midday leaf conductance. A comparison with humidity responses published for other conifers showed good agreement with this study. Seasonal change in total soil–plant resistance to water flux was nonlinearly correlated (R2 = 0.99) with change in predawn leaf water potential, an indirect measure of soil water potential.

Osmotic Adjustment in Expanding and Fully Expanded Leaves of Sunflower in Response to Water Deficits

1980 ◽  
Vol 7 (2) ◽  
pp. 181 ◽  
Author(s):  
MM Jones ◽  
NC Turner
Keyword(s):  
Water Potential ◽  
Leaf Water Potential ◽  
Osmotic Adjustment ◽  
Osmotic Potential ◽  
Leaf Water ◽  
Similar Degree ◽  
Tissue Water ◽  
Predawn Leaf Water Potential ◽  
Leaf Osmotic Potential ◽  
Osmotic Potentials

Sunflower plants were grown in large volumes of soil and slowly water-stressed by withholding water. The tissue water relationships of leaves at various stages of stress and of leaves of equivalent well watered controls were studied by the pressure chamber technique. Plants were stressed either when leaf 17 was expanding or when it was fully expanded. When expanding leaves reached a moderate level of stress (predawn leaf water potential of -0.9 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.1 MPa and 0.2 MPa, respectively. When fully expanded leaves were stressed to a similar degree (predawn leaf water potential of - 1.1 MPa), the osmotic potentials at full turgor and zero turgor were lower than the control values by 0.2 MPa and 0.3 MPa, respectively. The development of more severe stress in the fully expanded leaves was not accompanied by any further osmotic adjustment. However, when the expanding leaves reached a predawn leaf water potential of -2.3 MPa, the values of leaf osmotic potential at full turgor and zero turgor were lower than the values for the well watered plants by 0.4 MPa and 0.6 MPa, respectively. In expanding leaves prestressed to a predawn leaf water potential of -2.3 MPa, the osmotic potential at full turgor was significantly less than the control values for at least 7 days after rewatering. Stress had no effect on the bulk modulus of elasticity. It is concluded that both expanding and fully expanded sunflower leaves show osmotic adjustment.

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 Transpiration and water potential of young Quercus petraea (M.) Liebl. coppice sprouts and seedlings during favourable and drought conditions

2017 ◽  
Vol 63 (No. 7) ◽  
pp. 313-323 ◽  
Author(s):  
Stojanović Marko ◽  
Szatniewska Justyna ◽  
Kyselová Ina ◽  
Pokorný Radek ◽  
Čater Matjaž
Keyword(s):  
Forest Management ◽  
Water Potential ◽  
Leaf Water Potential ◽  
Weather Conditions ◽  
Growing Season ◽  
Adaptive Strategy ◽  
Quercus Petraea ◽  
Leaf Water ◽  
Individual Tree ◽  
Drought Conditions

Increased frequency and intensity of drought events consequently affect oak high forests with the process of further decline, compromised growth and questionable natural regeneration. To overcome such difficulties, new adaptive strategies are required. Coppicing, as the oldest way of forest management, might provide some solutions. In our study two contrasting management systems, sessile oak coppice and high forest, were compared at the initial stages of regeneration and forest development. The transpiration of young oak sprouts and seedlings was monitored using sap flow systems during the 2015 growing season. The study of transpiration also included leaf water potential measurements during three measurement campaigns with contrasting weather conditions. Coppice sprouts transpired significantly more than seedlings on the individual tree and stand level during the entire growing season 2015; particularly large differences were observed during drought conditions. Coppice sprouts experienced lower water limitations due to the voluminous and deeper root system as indicated by leaf water potential results. Presented results attribute young coppices as one of the promising adaptable forest management types with a better adaptive strategy at the extreme sites under water limiting conditions.

scholarly journals Relationships between chlorophyll content of vine leaves, predawn leaf water potential at veraison, and chemical and sensory attributes of wine

2020 ◽  
Vol 100 (14) ◽  
pp. 5251-5259
Author(s):  
Ramón Sánchez ◽  
María Rosa González ◽  
Encarnación Fernández‐Fernández ◽  
José Manuel Rodríguez‐Nogales ◽  
Pedro Martín
Keyword(s):  
Water Potential ◽  
Chlorophyll Content ◽  
Leaf Water Potential ◽  
Sensory Attributes ◽  
Leaf Water ◽  
Predawn Leaf Water Potential
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