Leaf area movements

Potassium channels can have a frequency of one or more channels per square micrometer of membrane surface area. Cellular control can be exerted on the opening of such K+ channels, because concentrations of cytosolic Ca2+ above 3 x 10-4 mol m-3 (0.3 p,M) can inhibit channel opening. Other ion channels in plant membranes are specific for Ca2+ or Cl-. Besides being sensitive to the electrical potential difference across a membrane, some channels apparently open upon stretching of a membrane. Also, many plant cells are excitable and can transmit action potentials, a process in which ion channels are undoubtedly involved. For example, action potentials have been measured for plants responsive to tactile stimuli, such as rapid leaf movements in Mimosa pudica and insectivorous plants (Dionaea spp., Drosera spp.), as well as along the phloem for many species. In addition, ion channels are involved in the long-term maintenance of specific ion concentrations in plant cells. 

The process of xenobiotic uptake through leaf cuticles is an area of active study and debate as to the detailed mechanisms involved. An illustration of the wide differences that can occur in the movement and pathways is shown in Figures 4a, 4b and 4c. Using CLSM and fluorescent probes of different lipophilicity, it can be shown that the uptake and movement (in the presence of a surfactant) through the cuticle proper, and into the... 

In an uptake experiment, over 90% of the radiolabeled pinoxaden was incorporated into the crops within 5 h when treatment solutions were applied in droplets to the adaxial leaf surface of two-leaved plants of barley, winter wheat or durum wheat. After 24 h, about 20% is translocated out of the treated leaf by basipetal movement below the treated area [87]. Cloquintocet does not affect the absorption or the movement of the herbicide within the crop. 

Cyclic sulfites and sulfates in organic synthesis have been reviewed in a Tetrahedron report. The reactions of several carbohydrate-based sulfite and sulfate derivatives with nitrogen, carbon and sulfur nucleophiles are reported. In the area of natural products, five sulfated saikosaponins containing the trisaccharide unit 28 have been isolated as minor constituents from Bupleurum rigidum. The leaf-movement hormones, sulfated phenolic glycosides 29, have been shown to be plant specific, rather than being common to all plants. ... 

Figure App. 15.1 illustrates the steps required to accomplish a three-stage countercurrent wash in a laboratory test. It is easiest to understand the principle behind this test by visualizing a continuous horizontal vacuum belt filter in operation (an indexing type is referred to here but the same applies to the models with continuous belt movement). The slurry enters the feed zone and the cake is formed (Step 1). The cloth indexes (follow Leaf C in the figure) and the formed cake move into the first wash area (Step 2). Another...

Control in area B shows translaminar movement to the other side of the leaf from the treatment area. Control in area A shows the more common... 

The results from screening the combinatorial libraries in the Crop Disease (CDM) and Insect Management (IM) HTS are shown in Table 3. A comparison of the screening results for the combinatorial libraries in each therapeutic area shows little overlap in bioactivity among the three areas. This is not surprising, as optimal physical properties for bioactivity are clearly different in each instance. (16) For exanqjle, while movement to the growing point of the plant is a requisite for a reliable herbicide, retention of the confound on or wiAin the leaf surface is a prerequisite for a contact, foliar-applied insecticide. 

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