Contribution of adventitious vs initial roots to growth and physiology of black spruce seedlings

Published in Physiologia Plantarum 165(1): 29-38. https://doi.org/doi:10.1111/ppl.12735

Black spruce (Picea mariana [Mill.] BSP) is a boreal tree species characterized by the formation of an adventitious root system. Unlike initial roots from seed germination, adventitious roots gradually appear above the root collar, until they constitute most of mature black spruce root system. Little is known about the physiological role they play and their influence on tree growth relative to initial roots. We hypothesized that adventitious roots present an advantage over initial roots in acquiring water and nutrients. To test this hypothesis, the absorptive capacities of the two root systems were explored in a controlled environment during one growing season. Black spruce seedlings were placed in a double-pot system allowing irrigation (25 and 100% water container capacity) and fertilization (with or without fertilizer) inputs independent to initial and adventitious roots. After 14 weeks, growth parameters (height, diameter, biomass), physiology (net photosynthetic rate, stomatal conductance, shoot water potential) and nutrient content (N, P, K, Ca and Mg foliar content) were compared. Most measured parameters showed no difference for the same treatment on adventitious or initial roots, except for root biomass. Indeed, fertilized black spruce seedlings invested heavily in adventitious root production, twice as much as initial roots. This was also the case when adventitious roots alone were irrigated, while seedlings with adventitious roots subjected to low irrigation produced initial root biomass equivalent to that of adventitious roots. We conclude that black spruce seedlings perform equally well through adventitious and initial roots, but if resources are abundant, they strongly promote development of adventitious roots.

Forests

Scientific Article

Ecosystems and Environment, Forestry Research, Forests, Silviculture

PERNOT, Clémentine, Nelson THIFFAULT and Annie DESROCHERS

2018

PDF available upon request

Available at the Direction de la recherche forestière

0031-9317

épinette noire, reboisement, physiologie, croissance, écosystèmes et environnement, sylviculture et rendement des plantations, picea mariana, nutrition, microsite, plantation, article scientifique de recherche forestière,ecosystems and environment, silviculture and yield of plantations, black spruce, reforestation