Foliar Absorption in Prunus domestica L. I. Nature and Development of the Surface Wax Barrier

1978 ◽  
Vol 5 (6) ◽  
pp. 749 ◽  
Author(s):  
DR Leece
Keyword(s):  
Seasonal Changes ◽  
Guard Cells ◽  
Physiological Age ◽  
Spray Application ◽  
Prunus Domestica ◽  
Abaxial Surface ◽  
Foliar Absorption ◽  
Surface Wax ◽  
Leaf Surfaces ◽  
Surface Waxes

Surface wax concentration, distribution, ultrastructure and wettability, as affected by developmental temperature, physiological age and seasonal changes, were studied on leaves of Prunus domestica. Surface waxes covered both leaf surfaces in an amorphous sheet, which extended over the guard cells on the abaxial surface. This sheet may have been thin or discontinuous above adaxial anticlinal walls. A secondary structure of wax ridges was superimposed on the amorphous sheet. Neither surface was readily wetted by water or by solutions of standard organic surfactants. The critical abaxial surface tension was estimated as 22-25 mNm-1 by Zisman plot, confirming that close-packed, oriented, methyl groups are exposed at the wax surface. Surface wax concentration was inversely proportional to temperature during leaf development. At any time, surface waxes differed little among leaves of different physiological ages, but wax concentration increased during the season on leaves of similar physiological age reaching a maximum on the abaxial surface in mid-summer and thereafter remaining constant. Results are discussed in terms of polar pathways through the cuticle, stomatal penetration and spray application strategies.

Composition and Ultrastructure of Leaf Cuticles From Fruit Trees, Relative to Differential Foliar Absorption

1976 ◽  
Vol 3 (6) ◽  
pp. 833 ◽  
Author(s):  
DR Leece
Keyword(s):  
Guard Cells ◽  
Fruit Trees ◽  
Abaxial Surface ◽  
Water Penetration ◽  
Foliar Absorption ◽  
Surface Wax ◽  
Leaf Surfaces ◽  
Surface Waxes ◽  
Wax Content ◽  
Cuticle Thickness

Differential foliar absorption of chemicals by peach, apple and orange was related to cuticle thickness, weight, surface wax and embedded wax content and to surface wax wettability, ultrastructure and composition. Surface wax concentration, especially on abaxial leaf surfaces, correlated well with resistance to foliar absorption. The abaxial surface wax on peach leaves was built up in layers around and over the guard cells (which are preferred paths of spray entry into leaves) whereas apple and orange guard cells were relatively wax-free. Peach surface waxes were more difficult to wet than orange waxes and, although more polar than orange waxes, may be more resistant to water penetration as they were rich in hydrocarbons and triterpenoids. Enhancement of foliar absorption may require improved partitioning of sprays through the surface waxes or the bypassing of the waxes via stomatal penetration.

Postemergence Activity of Sulfentrazone: Effects of Surfactants and Leaf Surfaces

Weed Science ◽  
1996 ◽  
Vol 44 (4) ◽  
pp. 797-803 ◽  
Author(s):  
Franck E. Dayan ◽  
Hannah M. Green ◽  
John D. Weete ◽  
H. Gary Hancock
Keyword(s):  
Inverse Relationship ◽  
Cuticular Wax ◽  
Severely Injured ◽  
Foliar Injury ◽  
Foliar Absorption ◽  
Yellow Nutsedge ◽  
Soybean Cultivars ◽  
Leaf Surfaces ◽  
Cellular Tolerance ◽  
Species Specific

Sulfentrazone was foliar applied at 34 and 56 g ai ha−1alone or in combination with surfactants to soybean cultivars Hutcheson and Centennial and to sicklepod, coffee senna, smallflower morningglory, velvetleaf, and yellow nutsedge. The most sensitive weeds, including coffee senna, smallflower morningglory, and velvetleaf, were severely injured by the lowest rate when sulfentrazone was applied with surfactants. Sulfentrazone provided the highest control of yellow nutsedge with X-77. Soybeans were not severely injured by sulfentrazone applied alone, but 55% foliar injury occurred when the herbicide was applied with X-77. However, the seedlings were not killed. Sicklepod was the most tolerant of the weeds tested. In the absence of surfactants, the order of radiolabeled sulfentrazone absorption by the foliage was Centennial (5.8%) = Hutcheson (8.5%) = coffee senna (10.4%) < yellow nutsedge (17.0%) < velvetleaf (22.3%) = smallflower morningglory (24%). Sicklepod leaves did not retain droplets containing sulfentrazone when no surfactant was used. Species with the highest foliar absorption also showed the greatest phytotoxic response to the herbicide. Addition of surfactants to the spray mixture enhanced the foliar absorption and overall phytotoxicity of sulfentrazone in the weeds. An inverse relationship was detected between the foliar absorption of sulfentrazone without surfactants and the amount of cuticular wax present on the leaves. No such correlation was observed when surfactants were used. Thus, surfactants overcame the barrier to absorption imposed by the cuticular wax and, under these conditions, selectivity apparently became dependent upon species-specific cellular tolerance to sulfentrazone.

scholarly journals Effect of epicuticular waxes from triticale on the feeding behaviour and mortality of the grain aphid, Sitobion avenae (Fabricius) (Hemiptera: Aphididae)

2016 ◽  
Vol 56 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Agnieszka Wójcicka
Keyword(s):  
Toxic Effect ◽  
Control Diet ◽  
Sitobion Avenae ◽  
Early Mortality ◽  
Epicuticular Waxes ◽  
Feeding Deterrence ◽  
Grain Aphid ◽  
Surface Wax ◽  
Choice Tests ◽  
Surface Waxes

AbstractSurface waxes from wax-covered triticale plants (RAH 122) were sprayed on plants of the waxless genotype RAH 366 or the surface waxes were used to make artificial diet preparations. The results were significant increases in the mortality of apterous adults of the grain aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae) at all concentrations tested in comparison with those aphids which fed on the control plants or aphids which were reared on the diets. In the choice tests, most aphids settled on plants without surface waxes or on diet preparations which did not have surface waxes (the controls). When the concentration of the surface waxes was increased on one of the plants or surface waxes were increased in the diet preparation, the number of wandering aphids increased. Those aphids which did not wander were mainly on the waxless control plants or on the waxless diet preparations. Aphids did settle on those plants or on the diet preparations which had 100 and 1,000 μg · g-1of surface wax. The aphids rarely settled on the diet preparations containing 10,000 μg ∙ g-1of surface waxes. From these observations it appears that surface waxes can act as a feeding deterrent. Since aphids on plants with surface waxes, or aphids which settled on diet preparations with surface waxes, started to die earlier than aphids fed only the control plants or the control diet preparations, it is possible that the surface waxes had a toxic effect that led to early mortality. Thus, it can be said that the surface waxes caused feeding deterrence and had a toxic effect on the aphids.

scholarly journals Interaction of surfactants with barley leaf surfaces: time-dependent recovery of contact angles is due to foliar uptake of surfactants

Planta ◽  
2021 ◽  
Vol 255 (1) ◽  
Author(s):  
Johanna Baales ◽  
Viktoria V. Zeisler-Diehl ◽  
Yaron Malkowsky ◽  
Lukas Schreiber
Keyword(s):  
Leaf Surface ◽  
Pure Water ◽  
Contact Angles ◽  
Time Dependent ◽  
Alcohol Ethoxylate ◽  
Leaf Physiology ◽  
Surfactant Solutions ◽  
Surface Wax ◽  
Leaf Surfaces ◽  
Barley Leaf

Abstract Main conclusion Time-dependent contact angle measurements of pure water on barley leaf surfaces allow quantifying the kinetics of surfactant diffusion into the leaf. Abstract Barley leaf surfaces were sprayed with three different aqueous concentrations (0.1, 1.0 and 10%) of a monodisperse (tetraethylene glycol monododecyl ether) and a polydisperse alcohol ethoxylate (BrijL4). After 10 min, the surfactant solutions on the leaf surfaces were dry leading to surfactant coverages of 1, 10 and 63 µg cm−2, respectively. The highest surfactant coverage (63 µg cm−2) affected leaf physiology (photosynthesis and water loss) rapidly and irreversibly and leaves were dying within 2–6 h. These effects on leaf physiology did not occur with the lower surfactant coverages (1 and 10 µg cm−2). Directly after spraying of 0.1 and 1.0% surfactant solution and complete drying (10 min), leaf surfaces were fully wettable for pure water and contact angles were 0°. Within 60 min (0.1% surfactant) and 6 h (1.0% surfactant), leaf surfaces were non-wettable again and contact angles of pure water were identical to control leaves. Scanning electron microscopy investigations directly performed after surfactant spraying and drying indicated that leaf surface wax crystallites were partially or fully covered by surfactants. Wax platelets with unaltered microstructure were fully visible again within 2 to 6 h after treatment with 0.1% surfactant solutions. Gas chromatographic analysis showed that surfactant amounts on leaf surfaces continuously disappeared over time. Our results indicate that surfactants, applied at realistic coverages between 1 and 10 µg cm−2 to barley leaf surfaces, leading to total wetting (contact angles of 0°) of leaf surfaces, are rapidly taken up by the leaves. As a consequence, leaf surface non-wettability is fully reappearing. An irreversible damage of the leaf surface fine structure leading to enhanced wetting and increased foliar transpiration seems highly unlikely at low surfactant coverages of 1 µg cm−2.

Wax Morphology and Gas Exchange of Peach and Apple Leaves as Influenced by Soybean Oil Emulsions and Rain

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 464a-464
Author(s):  
B. R. Bondada ◽  
C.E. Sams ◽  
D.E. Deyton ◽  
J.C. Cummins
Keyword(s):  
Gas Exchange ◽  
Soybean Oil ◽  
Stomatal Closure ◽  
Leaf Age ◽  
Oil Retention ◽  
Apple Leaves ◽  
Surface Wax ◽  
Leaf Surfaces ◽  
Oil Residue ◽  
Oil Emulsions

A study was conducted to investigate the influence of rain on retention of soybean oil emulsions and their influence on wax morphology and gas exchange of apple and peach leaves. Peach and apple trees were grown in 19-liter pots in a greenhouse (25 °C). Two different soybean oil emulsions were sprayed on trees in a randomized block design with five replications. Twenty-four hours after the oil sprays, the trees were subjected to three rainfall regimes, 0.25, 1.25, and 2.54 cm. The surface wax and the oil residue on leaves were determined gravimetrically after chloroform extraction. A negative relationship existed between rainfall and oil retention. Peach leaves receiving 0.25, 1.25, and 2.54 cm rainfall lost 19%, 62%, and 82% of the applied oil, respectively. There were no differences in oil retention between top, middle, and bottom layers of the canopy, indicating that leaf age did not influence oil retention. Oil residue loss from apple leaves was similar to that from peach. Scanning electron microscopy revealed that the leaf wax morphology was not affected by the soybean oil emulsions and occurred as striations on both leaf surfaces. However, one of the emulsions partially washed off the waxes from apple leaf surfaces whereas the other emulsion did not exhibit this phenomenon. Furthermore, both of the soybean oil emulsions induced partial or full stomatal closure, which influenced stomatal conductance and transpiration.

Infection of radiata and bishop pine by Mycosphaerella pini in California

2005 ◽  
Vol 35 (11) ◽  
pp. 2529-2538 ◽  
Author(s):  
John A Muir ◽  
Fields W Cobb, Jr.
Keyword(s):  
Variable Temperature ◽  
Guard Cells ◽  
Radiata Pine ◽  
Moisture Regime ◽  
Forest Trees ◽  
Pine Plantation ◽  
Abaxial Surface ◽  
Temperature Regimes ◽  
Pine Seedlings ◽  
Germ Tubes

Infection of radiata pine (Pinus radiata D. Don) and bishop pine (Pinus muricata D. Don) by Myco sphaerella pini Rostr. in Munk was determined on needles of infected forest trees in central to northern coastal California. Conidia from infected trees were used to inoculate radiata pine seedlings maintained in constant and (or) fluctuating moisture and temperature regimes. On needles of radiata pine but not bishop pine plantation trees, most conidial germ tubes grew directly towards and entered the nearest epistomatal opening. On inoculated radiata pine seedlings in infection chambers, germ tubes grew haphazardly and few entered openings. Germ tubes entered epistomatal openings more often on abaxial than adaxial needle surfaces of both plantation trees and inoculated seedlings, and more lesions developed on the abaxial surface. Simple hyphae penetrated through epistomatal chambers, between guard cells, and into substomatal chambers. On radiata pine plantation trees, germ tubes that penetrated below guard cells occasionally formed substomatal vesicles. On needles of northern race bishop pine that had few disease lesions per needle, substomatal vesicles were common and frequently partially disintegrated. On seedlings, "water-soaked" spots formed 5 days after hyphae of the fungus penetrated slightly below guard cells. Development of typical lesions was delayed when seedlings were initially exposed to up to 16 days of continuous mist spray and then kept dry for 8 weeks. Penetration on inoculated seedlings was significantly greater in a variable than in a constant air temperature regime on abaxial needle surfaces, and greater in 24 h/day than in a 16 h/day exposure of seedlings to mist spray. In both temperature regimes more needles were infected on seedlings exposed to 24 h/day mist spray and fewest were infected in the variable temperature, 16 h/day moisture regime.

Thin sections of plant cuticles demonstrating channels and wax platelets

1972 ◽  
Vol 50 (7) ◽  
pp. 1509-1511 ◽  
Author(s):  
D. A. Fisher ◽  
D. E. Bayer
Keyword(s):  
Guard Cells ◽  
Plantago Major ◽  
Thin Sections ◽  
Leaf Surfaces ◽  
Plant Cuticles ◽  
Entire Thickness ◽  
Young Leaves

Channels, possibly sites of wax precursor transport in vivo, and plates resembling wax were observed in thin sections of the cuticle of young leaves of Plantago major. The channels, which averaged 2.5 nm in diameter, were perpendicular to the surface and traversed the entire thickness of the cuticle. Channels appeared equally dense in the cuticles of both leaf surfaces and did not appear preferentially associated with guard cells or over anticlinal walls. Thus far channels have been found only in P. major.Wax platelets, which were parallel to the surface, were found in Ardisia crenata and similar appearing areas were found in P. major. The plates were thicker than the channels and when plates and channels were present together as in P. major the two sometimes merged.

Frequency and length of stomata of 21 Populus clones

1979 ◽  
Vol 57 (22) ◽  
pp. 2519-2523 ◽  
Author(s):  
S. G. Pallardy ◽  
T. T. Kozlowski
Keyword(s):  
Dry Weight ◽  
Relative Distribution ◽  
Stomatal Frequency ◽  
Abaxial Surface ◽  
Stomatal Characteristics ◽  
Independent Variables ◽  
Shoot Dry Weight ◽  
Leaf Surfaces ◽  
Surface Variation ◽  
Weight Data

Frequency and length of stomata of field-grown plants of 21 Populus clones were studied. All clones except one were amphistomatous, and all clones had the greatest number of stomata per unit of leaf area on the abaxial surface. Variation in stomatal frequency, length, and relative distribution of stomata between abaxial and adaxial leaf surfaces among clones was found. Although differences in stomatal frequency and length were observed in some cases between early and late leaves of a clone, pore area differences were small because of the tendency for leaves with fewer stomata to have larger stomata. Cluster analysis utilizing abaxial and adaxial stomatal frequency and length as independent variables indicated that stomatal characteristics were related to parentage. Relationships between clonal stomatal characteristics and preliminary shoot dry weight data were not significant.

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