Faculty Publications

Root Environmental Effects On Phi Thickening Production And Root Morphology In Three Gymnosperms

Document Type



Cryptomeria, Phi thickenings, Pinus, Root anatomy, Soil compaction, Waterlogging

Journal/Book/Conference Title

Canadian Journal of Botany





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Last Page



Phi thickenings, lignified thickenings found on the radial and tangential walls of root cortical cells, are present in a restricted number of angiosperms and gymnosperms. To test whether their occurrence is constitutive or environmentally induced, seedlings of Cryptomeria japonica (L.f.) D. Don (Cupressaceae, phi thickenings present), and Pinus aristata Engel. and Pinus rigida Mill. (Pinaceae, phi thickenings absent) were grown under conditions of waterlogging and soil compaction. After 4 months, five morphological characters and the presence and cross-sectional area of phi thickenings were measured. All measured aspects of seedling morphology were affected by the treatments, and the two treatment factors (waterlogging and compaction) interacted significantly with one another. Taproots were significantly shorter, lateral roots were shorter and fewer in number, and root:shoot ratios were smaller in waterlogged and compacted soil in all three species. Despite these morphological effects, phi thickening presence or absence did not vary, phi thickenings were always found in C. japonica and never in the two Pinus species. However, the phi ratio (the area occupied by phi thickenings relative to the total root area) decreased significantly with both waterlogging and compaction even though it remained unchanged with root maturity. Thus, although root morphology and phi thickening anatomy were significantly affected by the environment, the presence of phi thickenings was not, and is evidently a constitutive anatomical feature in the species examined. © 2005 NRC Canada.


Department of Biology

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DOI of published version