Leaf shading

Fig. 7. Root and shoot dry weight of wheat after 22 days of growth (5-leaf Stage) at various soil penetrometer resistances. Variations in penetrometer resistance were obtained by varying soil bulk density and water content. Symbols are as follows. Shape refers to bulk density (g cm ) 0,1.17 A, 1.29 , 1.37 <0, 1.41 V, 1.45. Shade refers to water content (g g dry soil) open symbols, 0.22 or 0.23 half-shaded, 0.25 closed, 0.27. Points are means s.E. (n = 6). Modified from Masle Passioura (1988).

Fig. 2. The effect of salinisation (NaCl, 50 mol m" at 14 days) on survival of leaves of rice plants. Open circles (salinised), closed circles (non-salinised), leaf 2 (leaf 1 is the oldest) to the left of the figure and leaf 4 to the right. The shaded area represents lost leaf life due to salinity. Data of P. Izard, T.J. Flowers A.R. Yeo (unpublished).

The desirability of partial shade on tea estates has been a controversial subject. Desirable effects include temperature moderation at the leaf surface, which decreases low-humidity stress, and an increased yield of chlorophyll, amino acid, and caffeine production. The undesirable effects include decreased photosynthetic activity and competition for water and solid nutrients by the shade tree employed. In general, the trend has been toward the elimination of shade in most black-tea growing areas. Green tea products benefit from the additional chlorophyll and amino acid pro-... 

Plant varieties used for green tea production usually have higher amino acid levels and lower catechin levels than those used for making black tea. Caffeine levels are slightly lower except in the finest grades,85 with variations attributed to shading and leaf processing. 

Practically all the coffee planted commercially comes from seed, except in the rather limited Robusta-growing region of Java where grafted plants are used. Coffee seeds are planted in seedbeds and are treated in about the same way all over the tropics. The mature and apparently healthy fruits are selected and the seeds are pressed out, washed and dried in the shade, and planted rather soon, because coffee seed viability is lost within a comparatively short while. Handled in this manner, the chances are lessened that coffee diseases will be carried by seeds. However, it has been proved experimentally that infected plants can be produced from seeds contaminated with both the coffee Colletotrichum and the coffee Cercospora from either field material or artificial inoculation. This contamination is probably not uncommon in plantation practice and thus far it is not of extreme importance. The Hemileia rust is probably not carried on the seed (93). The American leaf spot is not carried on seed (97). 

Fig. 9.11 Historical record of 8lsO in tree rings of long-leaf pine in southern Georgia correlated with the historical record of hurricanes in the area. Open circles = no documented tropical storms, solid squares = documented storms in area, shaded triangles = major tropical storm >400 km from site (Reprinted with permission from Miller, D. L. et al. Proc. Natl. Acad. Sci. 103, 14294 (2006), copyright 2006, National Academy of Sciences, USA)...

Herbs that enjoy dappled shade thrive on the edges of shrubs or by groups of small trees. Add a low-fertility soil improver on an annual basis in order to mimic the leaf litter layer that occurs naturally in woodland areas. Vigorous... 

Mexico. Decoction of the bark and dried branches is taken orally as an abortive and for diabetes. Decoction of the dried root is taken orally by pregnant humans as an abortive and for diabetes . Infusion of the shade-dried entire plant is taken orally to treat infectious diseases ". Decoction of the dried leaf is taken orally for treatment of diabetes. Hot water extract of the dried leaf is taken orally as a blood purifier to treat kidney problems, urinary tract infections, and frigidity for gallstones, rheumatism and arthritis, diabetes, wounds, and skin injuries, displacement of the womb, and paralysis and to dissolve tumors 5 United States. Hot water extract of the dried leaf is taken orally as a stimulating expectorant and tonic, for tuberculosis, and is drank by Indians of the Southwest for bowel cramps, as a diuretic, and for venereal disease. Hot water extract of the dried leaf is used externally for wound healing . Hot water extract of the dried plant is taken orally for cancer. Effects described are from multicomponent reaction ". 

Anticrustacean activity. Methylene chloride extracts of the dried leaf and root, at a concentration of 500 ppm, were inactive on Artemia salina. The assay system was intended to predict for antitumor activity. Methanol extract of the dried root, at a concentration of 500 ppm, was inactive on Artemia salina ° K Ethanol extract of the shade-dried seed was inactive on Artemia saliruf ° ... 

The photoprotection hypothesis for anthocyanins is attractive because it can explain why red-leafed plants occur across such diverse environments. In the tropics, for example, anthocyanins in flushing red leaves may provide a critical photoprotective role to the nascent chloroplasts until adequate levels of xanthophylls have been synthesized. In the understorey, anthocyanins might protect shade-acclimated plants from the effects of sunflecks, which can be 2000-fold brighter than the usual light level, or canopy gaps caused by tree blowdown. A photoprotective function of anthocyanins would also benefit leaves in... 

Sun leaves of different trees exhibit average Chi a+b levels of 400 to 700 mg/m2 leaf area (40 to 70 pg/cm2) and shade leaves have 380 to 570 mg/m2 leaf area (38 to 57 pg/cm2). As sun leaves possess thicker cell walls, a lower leaf... 

Lichtenthaler, H.K., Buschmann.C., Doll,M.,Fietz, H.-J., Bach, T., Kozel, U., Meier, D., and Rahmsdorf, U. 1981. Photosynthetic activity, chloroplast ultrastructure, and leaf characteristics of high-light and low-light plants and of sun and shade leaves. Photosynthesis Res. 2 115-141. 

Table 1. Stomatal density (SD), epidermal cell density (ED) and stomatal index (SI) of sun and shade leaves of Nothofagus solandri var. cliffortioides. Sun and shade leaves were collected at three localities (Fig. 2) Horrible Bog (HOR), Kawatiri Junction (KJ) and St. Arnaud (SA). Values are means of five leaves per light level (seven counts per leaf). The complete data set (total) was analyzed with a nested mixed-model ANOVA based on a general linear model, for comparisons within the individual localities a fully nested ANOVA was used.

Leaves from 61 georeferenced Q. kelloggii trees were collected from multiple populations over an altitudinal range of 1100-2400 m across California in the summer of 2003 (Fig. 1). The leaf samples were divided into sun, neutral or shade types based on the degree of undulation of the epidermal anticlinal cell walls, which is indicative of light levels during growth (Kiirschner 1997). 

One of the earliest indications of ozone injury on several plant species is an upper surface discoloration with a waxy appearance. This symptom often disappears completely a few hours after exposure is terminated. High dosages of ozone cause permanent necrotic lesions on susceptible leaf tissue. Permeability of cell membranes is apparently disrupted, and cell contents are allowed to leak into the intercellular spaces producing a water-soaked appearance. Upon drying, the tissue will totally collapse and turn white or various shades of brown. Lesions which extend through the entire thickness of the leaf are commonly referred to as bifacial... 

---