Deltoides Bartr Research Articles

Changes in Total Nitrogen, Soluble Protein, and Peroxidases in the Expanding Leaf Zone of Eastern Cottonwood

Nitrogen content and soluble protein and anodal peroxidase banding in acrylamide gel changed with leaf and internode development in the expanding leaf zone of eastern cottonwood (Populus deltoides Bartr.). Nitrogen per unit leaf area was high near the apex and decreased to a constant value at the sixth node below it. Soluble protein banding was qualitatively similar for leaves and internodes in this zone, but anodal peroxidases differed between leaves and internodes. The major leaf peroxidase band was absent from the second leaf below the apex but present in the fourth and sixth leaves; its appearance and intensification seemed to parallel the development of photosynthetic activity. The major internode peroxidase band was present in the apex, second, fourth, and sixth internodes, and intensified during internodal development. It is suggested that these two "isoenzymes" may have different functions in vivo.

Studies of the Hot Water Extractives of the Bark and Leaves of Populus deltoides Bartr.

The hot water extractives of the fresh smooth green bark and the fresh leaves of a Populus deltoides Bartr. tree cut in June and processed by the Waring Blendor technique in ethanol were extracted fractionally with ethyl acetate, and the individual ethyl acetate extracts were fractionated by elution chromatography with water, 20% ethanol, and 50% ethanol on polyamide columns. Important components found in the bark were salicortin, salicin, salicyl alcohol, pyrocatechol, ω-salicyloylsalicin, grandidentatin, grandidentoside, populoside, trichocarposide, and 6-methyldihydroquercetin. Important components found in the leaves were salicortin, salicin, salicyl alcohol, pyrocatechol, 1-O-p-coumaroyl-β-D-glucoside, populoside, ω-salicyloylsalicin, chrysin-7-glucoside, and a new glucoside, deltoidin, which has been identified as 2-O-salicyloylsalicin.

Growing Seasons of Cottonwood and Sycamore as Related to Geographic and Environmental Factors

The hypothesis that variation in dates of the beginning and end of growing seasons of eastern cottonwood (Populus deltoides Bartr.) and American sycamore (Platanus occidentalis L.) can be attributed to variation in air temperature andphotoperiod was tested by using data collected during a single year (1963) from trees widely distributed throughout their natural ranges. Dates of bud breaking and winter-bud formation were used as the criteria for the beginning and end of growing seasons. Correlation and regression analyses were used to elicit the relationships of these dates with latitude, altitude, air temperature, photoperiod, and with the dates of frost occurrence at the locations of the sampled trees. The growing season in these two species was not confined to the period between killing frost in spring and fall. The lengths of growing seasons were inversely related to the latitude. With increasing latitude, growth began later and stopped earlier. Both air temperature and photoperiod at the time of growth initiation and cessation varied with latitude. At a given latitude between 30°N and 50°N cessation of growth occurred at higher temperature than that at initiation of growth, and growth cessation between 33°N and 50°N was associated with shorter photoperiods than those at growth initiation. Temperature and photoperiod, acting in combination, appeared to be important, although not exclusive, factors in controlling the initiation and cessation of growth of these species. The regression line of monthly mean temperature on photoperiod on the day of growth initiation appeared to delineate a boundary between the period of dormancy and the active growing season. The cessation of growth could not be as clearly defined.

SURVIVAL AND GROWTH OF SHELTERBELT TREES AT THREE SPACINGS

Seedlings of Caragana arborescens Lam., Acer Negundo L., Ulmus americana L., Populus deltoides Bartr. and Fraxinus p. lanceolata Sarg. were planted in 3-row shelterbelts at spacings of 4, 8, and 16 feet at the Forest Nursery Station, Indian Head, Saskatchewan. Data for stand and height are presented after 17 years of growth. Survival of caragana, maple, and ash were not materially influenced by Spacing, but that of elm increased from 91 to 100% and of cottonwood from 0 to 25%, as spacings increased from 4 to 16 feet. Caragana was outstanding with 100% survival at all spacings. Maximum height of caragana and ash (15 and 19 feet, respectively) was obtained at the 8-foot spacings; while that of maple and elm (23 and 26 feet) was obtained at the 16-foot spacing.