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Seedlings of Pinus ponderosa Laws. from seeds collected in Arizona, California, and South Dakota were grown for 6 weeks under various combinations of constant air and soil temperatures from 7° C to 31° C, and combinations of day and night temperatures from 7° C to 23° C. Root growth responded more to soil temperature, while top growth responded more to air temperature. Both were significantly influenced by the interaction of air and soil temperature. Roots grew best in 15° C air and 23° C soil, while height growth was best in 23° C air and 23° C soil. Seedlings did not require an alternating day-night temperature, but grew best at constant 23° C. Epicotyl length, root penetration, number of lateral roots, and dry weight of roots were correlated with daily degree hours. The source of seed had a pronounced effect on final seedling size; seedlings of California source were largest, Black Hills source smallest.
Document Type: Journal Article
In cooperation with the Calif. Inst. of Technology and Northern Arizona Univ., Flagstaff, Forest Physiologist at Flagstaff, Ariz.
Publication date: September 1, 1967
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Forest Science is a peer-reviewed journal publishing fundamental and applied research that explores all aspects of natural and social sciences as they apply to the function and management of the forested ecosystems of the world. Topics include silviculture, forest management, biometrics, economics, entomology & pathology, fire & fuels management, forest ecology, genetics & tree improvement, geospatial technologies, harvesting & utilization, landscape ecology, operations research, forest policy, physiology, recreation, social sciences, soils & hydrology, and wildlife management.