Leaf surface wax

Bystrum et al. first described morphologic changes in leaf surface waxes of table beet exposed to photochemical oxidants these changes were different from those associated with aphid feeding. Comparison of oxidant injury with that produced by insects has since received attention from Hibben, who found that ozone injury to the leaves of four tree species produced smaller flecks, randomly spaced and darker than fleck injury along veins induced by a mesophyll-feeding leafhopper. 

When gas chromatography became established as an analytical technique, certain classes of metabolite proved particularly amenable to study. These were volatile oils (see monoterpenes), the constituents of leaf surface waxes and, in the form of their methyl esters, the fatty acid components of fixed oils and fats, particularly those occurring in seeds. Structural variation within each of these t)q)es of compound proved to be somewhat less pronounced than with many other groups of metabolites. Nevertheless, the classification of plant families on the basis of the chain length and degree of unsaturation of the predominant fatty acids was proposed (Smith, 1976). 

Effect of Combined Physical/Chemical Weathering of Protective Leaf Surface Waxes... 

The increased erosion (weathering) of plant cuticles by simulated "rain acidified with sulfuric acid may disrupt processes that occur at the leaf surface. The most important function of the cuticle is to reduce water (transpiration) loss. > Removal of leaf surface waxes has been reported to increase wettability of those surfaces.Leaves which had been wetted and dried are subsequently wetted more easily.The water repellency of a plant surface is important in preventing the establishment of infections from water-borne inocula.Dickinson proposed that the thigmotropic response of germ tubes of certain fungi is a function of the structure and thickness of the cuticle. Both of these features of cuticular waxes appear to be altered by simulated rain acidified with sulfuric acid. The apparent loss of surface... 

Isol. from leaf-surface wax of wheat Triticum compac-turn var. Little Club. Obt. as a mixt. with the 9-hy-droxy compd. Mp 69.5-70.5 . 

Stadler, E., Oviposition and feeding stimuli in leaf surface waxes, in Insects and the Plant Surface (B. Juniper and R, Southwood, eds.), 105-121, Arnold, London, 1986. 

Stadler, E. and H. R. Buser, Defense chemicals in leaf surface wax synergistically stimulate oviposition by a phytophagous insect, Experientia, 40, 1157-1159 (1984). 

To solve the problem of non-polar chemicals in water, Blaney (1975) used a suspension of leaf surface waxes in a 50 mM NaCl solution. Since our attempts to use this technique gave unclear results in the carrot rust fly, Psila rosae, we tested additional methods. The most promising results were obtained using 10 7o methanol extracts of leaf surfaces in a 100 mM NaCl solution as represented in Fig. 1.4 (StSdler, unpublished). We found no indication of damage or stimulation by methanol in different fly species. These results are in agreement with those of Dethier (1951) the 50% behavioral rejection threshold for methanol is about 5 to 10 molar for the blowfly, Phormia regina, and the cricket, Gryllus assimilis. 

Study of the phase behaviour of surfactants (which can be performed using polarizing microscopy) is crucial in the selection of adjuvants. Interaction of the above units with the agrochemical is crucial in determining performance (e.g. solubilization). Similar interactions may also occur between the above structural units and the leaf surface (wax solubilization). 

Kolattukudy Gamble 1995). In the case of fungal infection of leaves of some plant species, infection is also promoted by removal of leaf surface waxes by immersion of chloroform or another suitable organic solvent prior to the infection assay (Carver et al. 1990). Inoculation of the fungus is then followed by assaying for a necrotic or other hypersensitive response or phytoalexin production, and the effect of these responses on fungal proliferation. 

Carver, T.L.W., B.J. Thomas, S.M. Ingerson-Morris H.W. Roderick. 1990. The role of the abaxial leaf surface waxes of Lolium spp. in resistance to Erysiphe graminis. Plant Pathol. 39 573-583. 

EFFECTS OF POWDERY MILDEW ON THE LEAF SURFACE WAXES OF WHEAT... 

The isolation of the allomonal factor of L. hlrsutum was relatively straightforward and unremarkable as this factor was typical of many organic molecules in its solubility properties and was not apparently prone to thermal, photolytic or oxidative degradation. The biologically active principle could be removed from the leaf surface with a chloroform wash and could be selectively removed from unwanted pigments and waxes by redlssolvlng... 

Monquero, P.A., P.J. Christoffoleti, M.D. Osuna, R. De Prado Amian, A.J. Matas, and A. Heredia. (2004). Absorption, translocation, and metabolism of 14C-glyphosate and leaf surface and wax analysis. 4th International Weed Science Congress, p. 60, S15MT08P00. 

C below the melting point. The nature and the size of the exposed surface of the deposit on the leaf surface can be modified by spray adjuvants such as wetting agents, thickeners or particulating agents. The deposited pesticide may also interact with the target surface, with leaf exudates or with the polymeric wax-like surface of cutin. It may also physically penetrate the surface of the leaf. 

No physical removal of cuticle has been observed with microscopic and chemical studies when the cuticle is treated with a surfactant, although solubilization of waxes has been suggested. It is likely that orientation of surfactant molecules occurs towards the cuticle surface causing wetting and spreading of the spray droplets over the leaf surface. This would enhance the penetration of the herbicide solution into stomata, insect punctures, cracks, and other imperfections in the leaf surface. 

In the first case, the layer of solution is so thin that diffusion within it is probably unimportant. In the case of the mesophytes, to which group nearly all crops belong, surface oils and waxes rarely amount to as much as 100 /Ltgrams/sq. cm. of leaf surface (i.e., mean thickness less than 0.5/x on each side) (3,13). Internal oils, much less accessible, may be present in about the same amount (9). Some fruits may have more superficial oils or soft waxes—e.g., on apple skin there is about 400 /xgrams/sq. cm. (3). The polymeric cutin itself, highly lipophilic but not too swollen by... 

In the area of the leaf surface in contact with the . graminis film, the cuticle loses its original integrity as evidenced by the apparent dissolution of surface wax crystals. Within 60 min the film disappears and the surface of the conidium again assumes the morphology of the unstimulated state. 

They could remove the coat of waxes on the leaf surface, and so then the sea salt could penetrate into the cells and could kill the cells. I just wanted to know if this has been cleared in your country, or is it still in discussion The other point you mentioned quite rightly that NH 4 is no really neutralizing agent. In the soil it will be transformed into NO i, and nitric acid will contribute to acidity. The measurement of total acidity by just titrating the amount of acidity is a questionable thing. You have to determine the species of N0 3 and NH" 4 in the precipitation and add it to the acidity, so you have to do more than titrating... Well, I have a question what happens on the surface of leaves or other material in dry deposition of acids Maybe if you have a coat of SO2 which is then transformed into sulphuric acid, will this sulphuric acid be a permanent coat on the leaves and can nitric acid then be added to this ... 

Several woody plant species will react to exposure of simulated acid rain by forming foliar lesions. While the pH level of simulated acid rain that produced these lesions varies from species to species, the lesions themselves are generally yellow to brown necrotic spots or regions (see Table 1). Additionally, on two clones of poplar, galls were formed in response to simulated acid rain. Surface characteristics such as stomatal presence and density, trichome density, type and amount of epicuticular wax, leaf surface wettability and buffering capacity have all been shown to influence foliar injury by simulated acid rain. However, it may be... 

As with the other thiocarbamates, EPTC considerably inhibits wax deposition on the external leaf surface (Centner, 1966 Still etal., 970 Wilkinson and Hardcastle,... 

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