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Early root growth and architecture of fast- and slow-growing Norway spruce (Picea abies) families differ—potential for functional adaptation
- Hamberg, Leena, Velmala, Sannakajsa M, Sievänen, Risto, Kalliokoski, Tuomo, Pennanen, Taina
- Tree physiology 2017 v.38 no.6 pp. 853-864
- Picea abies, aerial parts, biomass, boreal forests, branches, fine roots, forest soils, image analysis, nutrients, phenotype, root growth, root tips, seedlings, tree physiology, trees
- The relationship between the growth rate of aboveground parts of trees and fine root development is largely unknown. We investigated the early root development of fast- and slow-growing Norway spruce (Picea abies (L.) H. Karst.) families at a developmental stage when the difference in size is not yet observed. Seedling root architecture data, describing root branching, were collected with the WinRHIZO™ image analysis system, and mixed models were used to determine possible differences between the two growth phenotypes. A new approach was used to investigate the spatial extent of root properties along the whole sample root from the base of 1-year-old seedlings to the most distal part of a root. The root architecture of seedlings representing fast-growing phenotypes showed ~30% higher numbers of root branches and tips, which resulted in larger root extensions and potentially a better ability to acquire nutrients. Seedlings of fast-growing phenotypes oriented and allocated root tips and biomass further away from the base of the seedling than those growing slowly, a possible advantage in nutrient-limited and heterogeneous boreal forest soils. We conclude that a higher long-term growth rate of the aboveground parts in Norway spruce may relate to greater allocation of resources to explorative roots that confers a competitive edge during early growth phases in forest ecosystems.