Root Growth of Black Walnut Trees Related to Soil Temperature, Soil Water Potential, and Leaf Water Potential
Abstract:The effects of soil temperature, soil water potential, and leaf water potential were evaluated on root length growth, number of growing roots, and suberization for three mature black walnut (Juglans nigra L.) trees in an oak-hickory forest in central Missouri. Rhizotrons were used to access the root systems. When only roots growing in wet soils were included, growth began at a soil temperature of 4°C and increased slowly to 13°C, with a more rapid increase above that. Growth rate peaked at 17° to 19°C and the number of growing roots peaked at 21°C, the highest temperature observed. When roots in dry soil were the only ones included in the analysis, root growth was low with a peak at 17°C. Root growth and number of growing roots decreased sharply as soil water potential decreased from 0 to -0.5 MPa, and approached zero as soil water potential went from -0.5 to -1.0 MPa. At low and high soil temperatures suberization rate was high, and at intermediate temperatures it was low. Suberization rate was low at high water potentials and increased as the soil dried. Forest Sci. 31:617-629.
Document Type: Journal Article
Affiliations: Professor, College of Forest Resources, University of Washington, Seattle, WA 98195
Publication date: September 1, 1985
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