Root structure and biomass partitioning in tilted plants from twisted- and straight-stemmed populations of Pinus pinaster Ait

• Published in: Trees (Berlin, West) Vol. 29; no. 3; pp. 759 - 774
• Main Authors: Garrido, Fermín, San Martín, Roberto, Lario, Francisco José, Sierra-de-Grado, Rosario
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.06.2015; Springer Nature B.V
• Subjects: Agriculture; Biomass; Biomedical and Life Sciences; Evergreen trees; Forestry; Life Sciences; Original Paper; Pine trees; Plant Anatomy/Development; Plant Pathology; Plant Physiology; Plant Sciences; Roots; Wind; Biomechanics; Stem straightness; Wind; Provenance test; Biomass; Roots
• ISSN: 0931-1890; 1432-2285
• DOI: 10.1007/s00468-015-1154-y

Key message Straight-stemmed populations of Pinus pinaster under mechanical stress allocate more biomass to the stem relative to the branches and show greater variability in the roots than twisted-stemmed populations. Pinus pinaster Ait. has a tendency to exhibit stem flexuosity that negatively affects the quality of its wood and its productivity. There is a wide geographical variability in this trait, and there is evidence of genetic control. We hypothesized that root structure and biomass allocation adjustments in response to a given mechanical stress might differ among populations of P. pinaster and might be related to the typical straightness of the stems of a given population. We analyzed root structure and biomass allocation in a provenance test in which plants were artificially tilted at 45° and naturally exposed to wind. Ten provenances were tested: five with typically straight-stemmed plants and five with twisted-stemmed plants. The wind affected the taper and the development of thickenings in the windward second-order roots, although the winds experienced were generally light. The straight-stemmed populations exhibited greater variability in the studied traits than the twisted-stemmed populations. This variability may reflect higher root responsiveness as well as various strategies to address mechanical stresses. Three possible additional distinguishing characteristics of various straight-stemmed populations are proposed: (a) greater allocation of biomass to the stem compared with the branches, (b) development of a thick, cylindrical taproot and tapered lateral roots and (c) strengthening of second-order roots with local thickening in the sectors of the root under tension.