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41.
Factors affecting diurnal stem contraction in young Douglas-fir 总被引:1,自引:0,他引:1
Diurnal fluctuation in a tree's stem diameter is a function of daily growth and of the tree's water balance, as water is temporarily stored in the relatively elastic outer cambial and phloem tissues. On a very productive site in southwestern Washington, U.S.A., we used recording dendrometers to monitor stem diameter fluctuations of Douglas-fir at plantation ages 7 and 8 and related the fluctuations to environmental variables measured on-site. Growing-season diurnal stem contraction (DSC) averaged 0.21% of stem diameter, while dormant-season DSC averaged 0.03% of stem diameter. Maximum daily stem diameter generally occurred between 7:00 and 9:00 Pacific Standard Time (PST) and minimum stem diameter occurred between 17:00 and 20:00 PST. Diurnal stem contraction during the growing season was predicted by a model that included vapor pressure deficit and solar radiation (adjusted R2 = 0.84). A similar model predicted DSC during the dormant season with an adjusted R2 = 0.26. Soil water availability was high, and soil water content was not correlated with DSC. On four of the coldest winter days (mean daytime air temperature <0 °C), large decreases in stem diameter were observed. Recording dendrometers, used for continuous diameter measurements throughout the growing season, have the potential to provide important information not only on tree growth but also on a tree's water balance. 相似文献
42.
Sociodemographic, health and lifestyle predictors of poor diets 总被引:1,自引:0,他引:1
Harrington J Fitzgerald AP Layte R Lutomski J Molcho M Perry IJ 《Public health nutrition》2011,14(12):2166-2175
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Rubeena Shaikh Axel Diederichsen Myrtle Harrington Jennifer Adam Robert L. Conner Lone Buchwaldt 《Genetic Resources and Crop Evolution》2013,60(1):193-201
Anthracnose caused by the fungal pathogen Colletotrichum truncatum is a severe disease of lentil (Lens culinaris Medikus subsp. culinaris) causing premature defoliation and deep penetrating lesions on the stems leading to wilting and plant death. A total of 579 accessions from 20 countries were obtained from four germplasm collections in Russia, Poland, Bulgaria and Hungary. The accessions were collected between 1923 and 1988 and comprised mostly landraces. Consequently, many of the resistant entries contained susceptible plants which necessitated one or two cycles of selection of individual resistant plants for selfing and re-testing with the pathogen. Under controlled environmental conditions, plants of each accession were inoculated at early flower with C. truncatum race Ct0 (isolate 95A8) and race Ct1 (isolate 95B36), separately. Scoring of symptoms included number of lesions on the main stem, lesion penetration into the stem and amount of wilting. Resistance was obtained by single plant selection in 23 lentil accessions (4.0 %). Fifteen lines were generated with resistance to race Ct1 (2.6 %), seven with resistance to race Ct0 (1.2 %), and one line with resistance to both races. This is the first report on resistance in L. culinaris to C. truncatum race Ct0 as well as to the two races combined. Seed of homozygous resistant lines can be requested from the corresponding author, and are labeled with their original accession number with the prefix either -Ct0, -Ct1 or -Ct0Ct1 indicating resistance to one or both races of C. truncatum. 相似文献
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The major tuber sugars—glucose, fructose and sucrose — in tubers of the Red Pontiac, Kennebec and Monona potato varieties harvested five times during the 1970 growing season were determined quantitatively by a gas-liquid Chromatographic technique. Also, chips were made from tubers and chip color was measured objectively and reported as Rd values. Red Pontiac tubers produced the darkest-colored chips (Rd-15.5), and its tubers tended to accumulate the highest levels of the three sugars. The major difference between Monona, which produced chips with the lightest color (Rd-21.1), and Kennebec (Rd-19.5) was the very low level of glucose found in the tubers of Monona. Varieties produced chips lightest in color at the second (8/31) or third (9/15) harvest dates. Conversely, darkest-colored chips were obtained from each variety at the fourth harvest date (9/28). This was attributed to the cool, wet weather. Sugar content also varied during the harvesting schedule. Glucose content changed little until late in the season when an increase occurred. Fructose tended to decline until the final harvest when a distinct increase was obtained. Sucrose declined significantly through the third harvest, but changed little thereafter. 相似文献
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Hereditary junctional mechanobullous disease in a foal 总被引:1,自引:0,他引:1
S R Frame D D Harrington J Fessler P F Frame 《Journal of the American Veterinary Medical Association》1988,193(11):1420-1424
Mechanobullous disease was diagnosed in a male Belgian foal that had sloughed hooves at 30 hours and at 6 and 12 days of age. Histologic and electron microscopic studies disclosed that lesions were the result of separation of the basal epithelial cell layer from the lamina densa of the basement membrane zone along the lamina lucida. Results of immunofluorescence on tissue specimens were negative for immunoglobulin deposition. The breeding history of the foal's dam indicated that the foal was produced from breeding of the mare to its full sibling stallion. This same mare had produced a female foal, sired by a different stallion, which also had sloughed hooves during the first 2 weeks of life and had similar histologic and electron microscopic changes. This newly recognized disease of horses most closely resembles junctional-type epidermolysis bullosa described in human beings. 相似文献
50.
We examined the influences of selected environmental variables on stomatal behavior and regulation of transpiration in 26-month-old Acacia koa Gray (koa) stands planted at spacings of 1 x 1 m or 2.5 x 2.5 m and grown without irrigation. Field measurements were made during recovery from an extended 60-day dry period with only 38 mm of precipitation. Biomass and leaf area were also measured at 3-month intervals over the first 24 months after planting and again following completion of the transpiration (T) and stomatal conductance (g(s)) measurements at about 26 months after planting. Transpiration was measured as sap flow through intact branches by a heat balance method. After a 22-day period during which 130 mm of rain were recorded, average T was substantially higher in the 2.5 x 2.5 m stand on both a leaf area and ground area basis even though leaf area index was about 3.5 times higher in the 1 x 1 m stand. After an additional 25 mm of rain during an 8-day period, T was still slightly higher on a leaf area basis in the 2.5 x 2.5 m stand but was about 3 times higher on a ground area basis in the 1 x 1 m stand. A strong stomatal response to humidity limited the increase in T with increasing evaporative demand. Values of g(s) in koa phyllodes were comparable to those reported for leaves of other mesic tropical forest trees, but were several times higher than those reported for Acacia species native to arid and semi-arid regions. The 1 x 1 m planting yielded three times more biomass per unit ground area than the 2.5 x 2.5 m planting. However, greater stand density, which resulted in more rapid depletion of soil water between rainfall inputs, was associated with lower growth efficiency and lower radiation conversion efficiency. 相似文献