Populus

At low irradiances, photosynthesis uses virtually 100% of the quanta, but in full sunlight, about 2000 imol quanta s , more quanta are available than can be used in photochemistry. Maximum rates of photosynthesis by Populus or Spinacia leaves of 15 and 70 jumol O2 m s , respectively, would require only 15 x 9 = 135 to 630 jumol quanta m s , or 10-40%. Leaves, therefore, need to be able to dissipate 60-90% of the quanta at high irradiance in an orderly manner such as non-radiative decay if they are to avoid the potentially damaging formation of oxygen radicals from reduced ferredoxin (Asada Takahashi, 1987). When plants are under a stress that restricts CO2 assimilation, excessive light will be reached at even lower irradiances. 

Hybrid poplars Populus deltoides x nigra) have attracted considerable interest since they are able to transport and metabolize—even though they do not generally degrade—diverse xenobiotics ... 

Van Aken B, JM Yoon, CL Just, JL Schnoor (2004) Metabolism and mineralization of hexahydro-1,3, 5-trinitro-l,3,5-triazine inside poplar tissues (Populus deltoides x nigra DN-34). Environ Sci Technol 38 4572-4579. 

The use of hybrid poplar (Populus deltoides X P. nigra) has been examined in a few investigations at sites contaminated with creosote. There are several issues that complicate the interpretation of these results, including the physical state of the contaminants, the mechanism of uptake from the soil, and translocation and metabolism in the plants. These have seldom been addressed in studies of PAHs. 

Even with these problems, attempts have been made to demonstrate that mulches suppress weeds allelopathically. Putnam and DeFrank (12) and Barnes and Putnam (39) used Populus wood shavings to separate chemical and physical effects of mulches. Their work indicated that certain mulches do possess allelopathic potential. Liebl and Worsham (9) and Shilling and Worsham (14) placed mulch on tilled soil, after tilling, in an attempt to provide the weeds with an exposure to light. Their work also indicated that at least part of the suppression of weeds by wheat and rye mulch is allelopathic. Thus, research to date indicates that both mulch and the lack of soil tillage contributes to the suppression of weeds in no-till cropping systems. 

Populus tremula I O-extracts, leaves benzoic acid, catechol inhib d. mycorrhizal fungal growth 132... 

Waterfowl feeding in areas subjected to extensive nickel pollution — such as smelters and nickel-cadmium battery plants — are at special risk because waterfowl food plants in those areas contain 500 to 690 mg Ni/kg DW (Eastin and O Shea 1981). Dietary items of the ruffed grouse (Bonasa umbellus) near Sudbury, Ontario, had 32 to 95 mg Ni/kg DW, whereas nickel concentrations in grouse body tissues usually contain less than 10% of the dietary level. Nickel concentrations in aspen (Populus tremula) from the crop of ruffed grouse near Sudbury ranged from 62 mg/kg DW in May to 136 mg/kg DW in September (Chau and Kulikovsky-Cordeiro 1995), which shows the role of season in dietary nickel composition. 

Columbia River Washington, 1985-87, near reactor, 90Sr Largetooth aspen, Populus grandidentata, 22eRa Near uranium tailing plant vs. control site Leaves 53 DW vs. 4 DW 4... 

Maximum values of average Cd concentrations are revealed in stem wood of the Aspen tree (Populus tremula). Median values of Cd content in other types of both deciduous and coniferous trees are lower than 0.2 mg/kg (Table 3, Figure 10). 

The dominant species are the spruce (Picea excelsa), the birch (Betula verrucosa, B. pubescens), the aspen (Populus tremula), and the alder (Aims incana). The moss and low bush layer is represented by the blueberry-bush (Vaccinium myrtiilus), hypnic mosses, separate species of cowberry (Vaccinium uliginosum) and flowering plants. The biomass of these Spruce Forest ecosystems reaches 10 ton/ha at the age of 100-150 years (Table 4). 

Dillmann, P., Populus, P., Fluzin, P., et al. (1997). Microdiffraction of synchrotron radiation - identification of non-metallic phases in ancient iron products. Revue De Metallurgie-Cahiers d Informations Techniques 94 267-268. 

Relatively pure xylan isolated from the holocellulose of aspen (Populus) wood is said to contain 85% of xylose residues.78 One of the characteristic properties of xylan is its ease of hydrolysis. Because it hydrolyzes much more readily than cellulose, mild acid treatment may be employed to bring about preferential hydrolysis of xylan from plant material. Xylose is ordinarily prepared in the laboratory by direct sulfuric acid hydrolysis of the native xylan in ground corn cobs.74 Hydrolysis in hydrochloric acid proceeds rapidly, but decomposition to furfural also occurs to some extent.76 A commercial method for the production of D-xylose from cottonseed hulls76 and straw77 and from corn cobs17 78 has been described. 

Salieaceae, 7-O-Methylaromadendrin from Populus alba," by A. Stoessl, A. Toth, E. Hardegger, and H. Kern, Phytochemistry, 10 (1971) 1972. 

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