Understanding structural roots system of 5-year-old African plum tree (D. edulis) of seed and vegetative origins (G. Don) H. J. Lam

Abstract

Root morphology of 5-year-old trees of Dacryodes edulis (G. Don) H. J. Lam of seed and two vegetative (cutting and marcot) origins were assessed in Cameroon. Roots of D. edulis trees of seed and vegetative origins were totally excavated and their root morphology described and quantified. Trees of seed origin were characterized by a tap root, reaching depths of about 1.2 m. Contrarily trees of cutting origin showed three strong vertical roots (d > 5 mm) with the longest reaching depths of 1.31 m. Trees of marcot origin were observed to have thick, relatively short prominent vertical roots, reaching depths of 1.15 m. At fixed lateral intra-row distances of 50 cm from tree bases, trees of seed and marcot origins recorded high root densities at soil depths of 0-20 cm; both differed significantly (p = 0.032) from those of trees of cutting origin. At soil depth of 60-100 cm, trees of cutting origin recorded the highest root density which however differ significantly (p = 0.016) from those of trees of both seed and marcot origins. D. edulis trees of seed origin had a tap root system, whereas trees of vegetative origin (cuttings and marcots) had developed prominent main adventitious roots growing vertically (sinker roots), into greater depths and a wider/deeper lateral root spread than seedlings. This could be a vital adaptation to the absence of a genetically determined tap roots in trees of vegetative origins so as not to compromise the acquisition of soil-based resources (water and dissolved ions) and anchorage.