Leaves orientation

Terrestrial BMOs have also been widely used for monitoring environmental contaminants. In particular, the lipid-like waxy cuticle layer of various types of plant leaves has been used to monitor residues of HOCs in the atmosphere. However, some of the problems associated with aquatic BMOs apply to terrestrial BMOs as well. For example, Bohme et al. (1999) found that the concentrations of HOCs with log KoaS < 9 (i.e., those compounds that should have attained equilibrium) varied by as much as 37-fold in plant species, after normalization of residue concentrations to levels in ryegrass (Lolium spp.). These authors suggested that differences in cuticular wax composition (quality) were responsible for this deviation from equilibrium partition theory. Other characteristics of plant leaves may affect the amount of kinetically-limited and particle-bound HOCs sampled by plant leaves but to a lesser extent (i.e., <4-fold), these include age, surface area, topography of the surface, and leaf orientation. 

Forseth I. N. and Ehleringer J. R. (1983) Ecophysiology of two solar tracking desert winter annuals IV. Effects of leaf orientation on calculated daily carbon gain and water use efficiency. Oecologia 5, 10—18. 

Murchie EH, Chen Y, Hubbart S, Peng S and Horton P (1999) Interactions between senescence and leaf orientation determine in situ patterns of photosynthesis and photoinhibition in field grown rice. Plant Physiol 119 553—563... 

Three common subalpine species were selected Mahonia repens, Rumex densiflorus and Populus tremuloides. Mahonia repens is a low stature understory shrub with horizontal foliage. Rumex densiflorus and Populus tremuloides, an open-growing herb and tree, respectively, have primarily vertical leaf orientation. Plants grew in an Artemisia-dominated forest opening and in the adjacent understory of a dense stand of Pinus contorta at ca. 300 m in the Medicine Bow Mountains, Wyoming. The forest opening and understory were selected... 

The physiological and anatomical basis of functional symmetry are currently under investigation. Low stomatal conductance when leaves of Rumex densiflorus were illuminated on the abaxial surface suggest stomata on this surface may have greater sensitivity to light5>o 7 despite vertical leaf orientation, and thus limit gas exchange. Photosynthetic asymmetry of M. repens, however, appears to be under... 

It could be suggested that the reduction in interception of radiation consequent upon leaf orientation and mutual shading is a water conservation mechanism. However, water use efficiency (WUE), calculated as A/E, increases with PPFD (Fig. 6). 

The data presented in Figs. 1 and 2 indicate that C assimilation by S. plumieri growing in an open, exposed habitat (leaf area index (LAI) of approximately 1) is limited by intercepted PAR. This is a consequence of both canopy architecture (leaf orientation and mutual shading) and leaf anatomy (Figs. 4 and 5) The reduced interception of radiation does not appear to be a water conservation mechanism as instantaneous values of WUE increase with PPFD (Fig. 6) and on a daily... 

The lower surface of the leaf appears to have as much chlorophyllous tissue as the upper surface although the average ratio of PAR intercepted by the upper and lower surfaces is 3 5 1 (this value varies considerably with leaf orientation and time of day). C assimilation is able to respond to irradiances in excess of those intercepted by the leaf (Fig. 3) Furthermore, even at infinite stomatal conductance, values of c are inadequate to saturate A at high PPFD (Fig. 7) Thus S. plumieri appears to have a photosynthetic capacity in excess of that realized in the field. A similar phenomenon has been reported for Cistus salvifolius, a semi-deciduous Mediterranean shrub (5) This implies a N investment in the photosynthetic apparatus in excess of that utilized. In a sand dune environment low in soil N (l), this poses interesting ecological questions. 

Neither Fleischer (1915-1922) nor Brotherus (1925) provided subdivisions of the Amblystegiaceae above the genus level. Their generic subdivisions were clearly based on a few, easily observable characters, such as leaf orientation and shape, development of the vegetative leaf costa and leaf border, leaf lamina cell shape, the presence or absence of paraphyllia, and the habitat of the species (cf., Brotherus, 1925). 

Leaf orientation Straight Squarrose Falcate Straight or falcate... 

Pressure Leaf Filters Sometimes called tank filters, they consist of flat filtering elements (leaves) supported in a pressure shell. The leaves are circ ilar, arc-sided, or rectangular, and they have filtering surfaces on both faces. The shell is a cylindrical or conical tank. Its axis may be horizontal or vertical, and the filter type is described by its shell axis orientation. 

Vertical Pressure Leaf Filters are essentially the same as Horizontal Plate Filters except for the orientation of the filter elements which are vertical rather than horizontal. They are applied for the polishing slurries with very lov solids content of 1-5% or for cake filtration with a solids concentration of 20-25%. As with the horizontal plate filter the vertical leaf filters are also well suited for handling flammable, toxic and corrosive materials since they are autoclaved and designed for hazardous environments when high pressure and safe operation are required. Likewise, they may be readily jacketed for applications whenever hot or cold temperatures are to be preserved.The largest leaf filters in horizontal vessels have a filtration area of 300 m and vertical vessels 100 m both designed for an operating pressure of 6 bar. 

Many studies have been reported on extractability and concentration of protein from leafy plants (13, 14). While it is more efficient to consume the leafy vegetable or fruit directly, considerable quantities of less available protein can be made available through extraction and concentration into LPC. As pointed out by Pirie (13) and Kohler Knuckles (14), an LPC processing plant could be oriented near packinghouses for leafy vegetables so that leaves, stems, and stalks trimmed from these vegetables before being sent to market, could subsequently be extracted for protein. Leaf protein processes are covered in more detail in another chapter. 

Dust Applications to Control Leaf Mildew in Orient... 

Rust, Oriental Rust, Leaf Disease, Leaf Rust... 

Mayne, Thomas, and others (38, 60, 81) have observed in the Orient that active defoliation from coffee leaf rust will leave unhealed places at the points where unseasonably dropped leaves were attached to stems. Into the leaf traces left exposed Colletotrichum and similar weakly parasitic organisms will enter and cause dieback. Many gross observations in the western tropics on chronic deterioration, paralleling... 

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