scholarly journals Quantitative studies on the wetting of leaves by water

1947 ◽  
Vol 134 (877) ◽  
pp. 503-522 ◽  
Keyword(s):  
Contact Angle ◽  
Water Content ◽  
Leaf Surface ◽  
Diurnal Fluctuation ◽  
Leaf Water Content ◽  
Triticum Vulgare ◽  
Quantitative Studies ◽  
Stomatal Behaviour ◽  
Detached Leaves ◽  
Advancing Contact Angle

Quantitative studies on the wetting by water of the exterior surfaces of leaves of Sinapis arvensis, Triticum vulgare , and other plants, have been made, using advancing contact angle as a measure of the extent to which wetting takes place. The magnitude of the contact angle of water on a leaf surface has been found to vary regularly with the position of the leaf on the plant and to show also a characteristic diurnal fluctuation through a range which may be as much as 30°. The diurnal variations in contact angle are shown to be correlated with changes in leaf water content. On detached leaves contact angle varies markedly as wilting proceeds, this change being reversible on recovery of turgor. Evidence is presented to show that these variations in the behaviour of water on leaves are caused by changes in the degree of corrugation of the leaf surface produced by changes in the water content of the tissues. The events in the diurnal cycle are explained on this basis. The significance of the observed phenomena in connexion with the retention of water by leaves, the exchange of water and dissolved substances between leaf and water, and stomatal behaviour, is discussed.

scholarly journals Leaf surface structures enable the endemic Namib desert grass Stipagrostis sabulicola to irrigate itself with fog water

2012 ◽  
Vol 9 (73) ◽  
pp. 1965-1974 ◽  
Author(s):  
A. Roth-Nebelsick ◽  
M. Ebner ◽  
T. Miranda ◽  
V. Gottschalk ◽  
D. Voigt ◽  
...  
Keyword(s):  
Contact Angle ◽  
Leaf Surface ◽  
Contact Angle Hysteresis ◽  
Maximum Size ◽  
Large Degree ◽  
Namib Desert ◽  
Fog Water ◽  
Water Conduction ◽  
Key Factor ◽  
Advancing Contact Angle

The Namib grass Stipagrostis sabulicola relies, to a large degree, upon fog for its water supply and is able to guide collected water towards the plant base. This directed irrigation of the plant base allows an efficient and rapid uptake of the fog water by the shallow roots. In this contribution, the mechanisms for this directed water flow are analysed. Stipagrostis sabulicola has a highly irregular surface. Advancing contact angle is 98° ± 5° and the receding angle is 56° ± 9°, with a mean of both values of approximately 77°. The surface is thus not hydrophobic, shows a substantial contact angle hysteresis and therefore, allows the development of pinned drops of a substantial size. The key factor for the water conduction is the presence of grooves within the leaf surface that run parallel to the long axis of the plant. These grooves provide a guided downslide of drops that have exceeded the maximum size for attachment. It also leads to a minimum of inefficient drop scattering around the plant. The combination of these surface traits together with the tall and upright stature of S. sabulicola contributes to a highly efficient natural fog-collecting system that enables this species to thrive in a hyperarid environment.

Influence of leaf surface wax and leaf area to water content ratio on cuticular transpiration in western conifers, U.S.A.

1990 ◽  
Vol 20 (9) ◽  
pp. 1306-1311 ◽  
Author(s):  
Julian L. Hadley ◽  
William K. Smith
Keyword(s):  
Water Content ◽  
Leaf Surface ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Forest Trees ◽  
Cuticular Transpiration ◽  
Saturated Water ◽  
Surface Wax ◽  
Saturated Water Content ◽  
Leaf Surface Wax

High cuticular water loss, desiccation, and leaf mortality during winter in conifers at alpine timberline represent especially dramatic examples of the ecophysiological importance of cuticular transpiration. However, little research has been conducted on the winter water relations of forest trees, even though recent evidence suggests a potentially high leaf mortality due, at least in part, to winter desiccation. Two factors that could have important influences on cuticular transpiration, leaf surface wax and the ratio of leaf area (A) to saturated water content (Mw), were compared for six conifer species common to the central Rocky Mountains, United States. Leaves were collected from forest trees at the end of winter (May) to compare the amount of leaf surface wax, cuticular conductance to water vapor (gc), and leaf water content. Decreases in relative leaf water content were much more linearly related to transpiration per unit saturated water content than either gc or A/Mw, separately. Only A/Mw appeared correlated with the rate of cuticular transpiration. Also, linear increases in gc occurred with increasing leaf water content. Estimated desiccation resistance during winter corresponded closely to the degree of drought tolerance characterized previously for each species based only on summer growth conditions. Thus, winter desiccation resistance may be an important, yet under-emphasized, ecological factor influencing conifer distribution patterns.

scholarly journals Extracuticular Wax and Contact Angle Measurements on Wheat (Triticum Vulgare L.)

1967 ◽  
Vol 20 (3) ◽  
pp. 509 ◽  
Author(s):  
JH Troughton ◽  
DM Hall
Keyword(s):  
Contact Angle ◽  
Leaf Surface ◽  
Flag Leaf ◽  
Contact Angles ◽  
Abaxial Surface ◽  
Triticum Vulgare ◽  
Angle Measurements ◽  
Abaxial Leaf Surface ◽  
Contact Angle Measurements ◽  
Plant Grown

Extracuticular wax and contact angles on wheat were studied because of their influence on the retention of chemical sprays and on disease resistance. Wax formed extensive deposits on wheat, irrespective of variety, stage of growth, or part of the plant, and these deposits overlaid or projected from the cuticle as platelets and rodlets. Platelets covered the adaxial and abaxial leaf surfaces of seedlings and some mature plants, while a net of rodlets covered the ear, culm, sheath, and flag leaf abaxial surface. Rods were occasionally present on the abaxial surface of mature vegetative leaves. Wax influenced the advancing contact angle of water droplets on wheat. Contact angles were all high, i.e. greater than 130� and generally about 150�. The contact angle on the adaxial leaf surface was higher than on the abaxial leaf surface, except on glasshouse-grown reproductive plants, where there was no difference between the two sides. Seedlings had higher contact angles than mature plants, but there was no trend in contact angle with tissue age within a leaf or within a mature plant. The contact angle on the flag leaf of glasshouse-grown reproductive Aotea plants was 24� higher than on a similar plant grown in the field.

Salinity Damage to Norfolk Island Pines Caused by Surfactants. III. Evidence for Stomatal Penetration as the Pathway of Salt Entry to Leaves

1978 ◽  
Vol 5 (3) ◽  
pp. 397 ◽  
Author(s):  
AM Grieve ◽  
MG Pitman
Keyword(s):  
Surface Tension ◽  
Contact Angle ◽  
Leaf Surface ◽  
Sea Water ◽  
Sea Spray ◽  
Water Spray ◽  
Araucaria Heterophylla ◽  
Norfolk Island ◽  
Advancing Contact Angle ◽  
Sea Coast

The paper describes the effect of varied surfactant concentrations on penetration of NaCl into leaves of Norfolk Island Pine, Araucaria heterophylla (Salisb.) Franco. It confirms that the damage observed along the sea-coast in Sydney is similar to that produced by high NaCl levels in the foliage. The effect of surfactant in increasing NaCl uptake from sea-water spray is related to the reduction in surface tension and to the advancing contact angle of the spray on the leaf surface. It is suggested that sea-spray enters A. heterophylla needles through the stomata, and that the cuticle is particularly resistant to NaCI, compared with other plant species. Similar penetration and damage was found with sprays of CaCl2, MgCl2 and KCl showing that the damage was not due specifically to NaCI.

scholarly journals THz Water Transmittance and Leaf Surface Area: An Effective Nondestructive Method for Determining Leaf Water Content

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4838 ◽  
Author(s):  
Pagano ◽  
Baldacci ◽  
Ottomaniello ◽  
Dato ◽  
Chianucci ◽  
...  
Keyword(s):  
Water Content ◽  
Surface Area ◽  
Pathogenic Bacteria ◽  
New Technologies ◽  
Leaf Surface ◽  
Quantum Cascade Lasers ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Vitis Vinifera L ◽  
Leaf Surface Area

Water availability is a major limiting factor in plant productivity and plays a key role in plant species distribution over a given area. New technologies, such as terahertz quantum cascade lasers (THz-QCLs) have proven to be non-invasive, effective, and accurate tools for measuring and monitoring leaf water content. This study explores the feasibility of using an advanced THz-QCL device for measuring the absolute leaf water content in Corylus avellana L., Laurus nobilis L., Ostrya carpinifolia Scop., Quercus ilex L., Quercus suber L., and Vitis vinifera L. (cv. Sangiovese). A recently proposed, simple spectroscopic technique was used, consisting in determining the transmission of the THz light beam through the leaf combined with a photographic measurement of the leaf area. A significant correlation was found between the product of the leaf optical depth (τ) and the leaf surface area (LA) with the leaf water mass (Mw) for all the studied species (Pearson’s r test, p ≤ 0.05). In all cases, the best fit regression line, in the graphs of τLA as a function of Mw, displayed R2 values always greater than 0.85. The method proposed can be combined with water stress indices of plants in order to gain a better understanding of the leaf water management processes or to indirectly monitor the kinetics of leaf invasion by pathogenic bacteria, possibly leading to the development of specific models to study and fight them.

scholarly journals Leaf water content estimation using top-of-canopy airborne hyperspectral data

2021 ◽  
Vol 102 ◽  
pp. 102393
Author(s):  
Rahul Raj ◽  
Jeffrey P. Walker ◽  
Vishal Vinod ◽  
Rohit Pingale ◽  
Balaji Naik ◽  
...  
Keyword(s):  
Water Content ◽  
Hyperspectral Data ◽  
Leaf Water ◽  
Leaf Water Content

scholarly journals Simulating Heat Stress of Coal Gangue Spontaneous Combustion on Vegetation Using Alfalfa Leaf Water Content Spectral Features as Indicators

2021 ◽  
Vol 13 (13) ◽  
pp. 2634
Author(s):  
Qiyuan Wang ◽  
Yanling Zhao ◽  
Feifei Yang ◽  
Tao Liu ◽  
Wu Xiao ◽  
...  
Keyword(s):  
Heat Stress ◽  
Water Content ◽  
Spontaneous Combustion ◽  
Leaf Water ◽  
Coal Gangue ◽  
Leaf Water Content ◽  
Spectral Features ◽  
Lasso Regression ◽  
Stress Assessment ◽  
First Derivative

Vegetation heat-stress assessment in the reclamation areas of coal gangue dumps is of great significance in controlling spontaneous combustion; through a temperature gradient experiment, we collected leaf spectra and water content data on alfalfa. We then obtained the optimal spectral features of appropriate leaf water content indicators through time series analysis, correlation analysis, and Lasso regression analysis. A spectral feature-based long short-term memory (SF-LSTM) model is proposed to estimate alfalfa’s heat stress level; the live fuel moisture content (LFMC) varies significantly with time and has high regularity. Correlation analysis of the raw spectrum, first-derivative spectrum, spectral reflectance indices, and leaf water content data shows that LFMC and spectral data were the most strongly correlated. Combined with Lasso regression analysis, the optimal spectral features were the first-derivative spectral value at 1661 nm (abbreviated as FDS (1661)), RVI (1525,1771), DVI (1412,740), and NDVI (1447,1803). When the classification strategies were divided into three categories and the time sequence length of the spectral features was set to five consecutive monitoring dates, the SF-LSTM model had the highest accuracy in estimating the heat stress level in alfalfa; the results provide an important theoretical basis and technical support for vegetation heat-stress assessment in coal gangue dump reclamation areas.

scholarly journals Accumulation of Silicon and Changes in Water Balance under Drought Stress in Brassica napus var. napus L.

Plants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 280
Author(s):  
Diana Saja-Garbarz ◽  
Agnieszka Ostrowska ◽  
Katarzyna Kaczanowska ◽  
Franciszek Janowiak
Keyword(s):  
Abscisic Acid ◽  
Drought Stress ◽  
Stomatal Conductance ◽  
Water Balance ◽  
Water Content ◽  
Oilseed Rape ◽  
Potential Evapotranspiration ◽  
Leaf Water Content ◽  
Optimal Conditions ◽  
Abscisic Acid Level

The aim of this study was to investigate the accumulation of silicon in oilseed rape and to characterize the changes in chosen water balance parameters in response to drought. The following parameters were estimated: water content, osmotic and water potential, evapotranspiration, stomatal conductance and abscisic acid level under optimal and drought conditions. It was shown that oilseed rape plants accumulate silicon after its supplementation to the soil, both in the case of silicon alone and silicon together with iron. It was revealed that silicon (without iron) helps maintain constant water content under optimal conditions. While no silicon influence on osmotic regulation was observed, a transpiration decrease was detected under optimal conditions after silicon application. Under drought, a reduction in stomatal conductance was observed, but it was similar for all plants. The decrease in leaf water content under drought was accompanied by a significant increase in abscisic acid content in leaves of control plants and those treated with silicon together with iron. To sum up, under certain conditions, silicon is accumulated even in non-accumulator species, such as oilseed rape, and presumably improves water uptake under drought stress.

Spectral assessments of wheat plants grown in pots and containers under saline conditions

2013 ◽  
Vol 40 (4) ◽  
pp. 409 ◽  
Author(s):  
Harald Hackl ◽  
Bodo Mistele ◽  
Yuncai Hu ◽  
Urs Schmidhalter
Keyword(s):  
Water Potential ◽  
Water Content ◽  
Aboveground Biomass ◽  
Leaf Water ◽  
Leaf Water Content ◽  
Spectral Indices ◽  
Fresh Weight ◽  
Normalised Difference Vegetation Index ◽  
Spectral Sensing ◽  
Reflectance Ratio

Spectral measurements allow fast nondestructive assessment of plant traits under controlled greenhouse and close-to-field conditions. Field crop stands differ from pot-grown plants, which may affect the ability to assess stress-related traits by nondestructive high-throughput measurements. This study analysed the potential to detect salt stress-related traits of spring wheat (Triticum aestivum L.) cultivars grown in pots or in a close-to-field container platform. In two experiments, selected spectral indices assessed by active and passive spectral sensing were related to the fresh weight of the aboveground biomass, the water content of the aboveground biomass, the leaf water potential and the relative leaf water content of two cultivars with different salt tolerance. The traits were better ascertained by spectral sensing of container-grown plants compared with pot-grown plants. This may be due to a decreased match between the sensors’ footprint and the plant area of the pot-grown plants, which was further characterised by enhanced senescence of lower leaves. The reflectance ratio R760 : R670, the normalised difference vegetation index and the reflectance ratio R780 : R550 spectral indices were the best indices and were significantly related to the fresh weight, the water content of the aboveground biomass and the water potential of the youngest fully developed leaf. Passive sensors delivered similar relationships to active sensors. Across all treatments, both cultivars were successfully differentiated using either destructively or nondestructively assessed parameters. Although spectral sensors provide fast and qualitatively good assessments of the traits of salt-stressed plants, further research is required to describe the potential and limitations of spectral sensing.

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