effect of unidirectional stem flexing on shoot and root morphology and architecture in young Pinus sylvestris trees

• Published in: Canadian journal of forest research Vol. 33; no. 11; pp. 2202 - 2209
• Main Authors: Mickovski, S.B, Ennos, A.R
• Format: Journal Article
• Language: English
• Published: Ottawa, Canada NRC Research Press 01.11.2003; National Research Council of Canada; Canadian Science Publishing NRC Research Press
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Biomass; dry matter partitioning; Economic plant physiology; Ecosystems; Environmental aspects; Evergreen trees; forest trees; Fundamental and applied biological sciences. Psychology; General aspects; Growth and development; lateral roots; loads; mechanical stress; Morphogenesis, differentiation, rhizogenesis, tuberization. Senescence; Morphology; Pine trees; Pines; Pinus sylvestris; plant architecture; Plant growth; Plant physiology and development; root systems; Roots; Roots (Botany); seedlings; Seeds; shoots; Stress (Physiology); Trees; Vegetative apparatus, growth and morphogenesis. Senescence; Windthrow; Wood; System architecture; Root; Simple bending; Ecophysiology; Pinus sylvestris; Stem; Biomechanics; Morphogenesis; unidirectional flexing; Morphology; Vegetative apparatus; Softwood forest tree; Forestry; Gymnospermae; Above ground plant part; Coniferales; Physiology; Spermatophyta; Shoot; One dimensional system; Below ground plant part
• DOI: 10.1139/x03-139
• ISSN: 0045-5067

Mechanical stresses experienced by a tree during lateral loading may cause alterations in both shoot and root growth (thigmomorphogenesis). Many of the previous studies on this subject have concentrated on shoot responses to lateral loads, while root system responses to stresses caused by external loading have been investigated only in more recent years, and even then only rarely in trees. This study presents the effect of unidirectional stem flexure of young Scots pine (Pinus sylvestris L.) on their root system morphology and architecture. Apart from the changes to the parts of the tree aboveground, unidirectional periodical flexing induced an increase in total root cross-sectional area and larger biomass allocation to the roots parallel to the plane of flexing, which in turn resulted in a larger number of major lateral roots with larger cross-sectional area in the plane of flexing. Since there were no significant differences in root to shoot ratio or the mechanical properties of wood between flexed and unflexed trees in this study, the increase in the lateral resistance in flexed trees was associated with the greater proportion of total root biomass allocated to the proximal major lateral roots, which was an adaptive mechanism for improvement of the trees' anchorage.