GROWTH STRATEGIES AND BIOMASS DISTRIBUTION IN Pinus pseudostrobus UNDER DIFFERENT CONDITIONS OF COMPETITION

Abstract

Competition intensity at which individual plants grow is an important factor in their survival, biomass production and architecture; characteristics that interact with their genotype. In this study, we evaluated the effect of different levels of competition in 13 juvenile families of Pinus pseudostrobus Lindl. half-siblings in terms of plant survival, growth and biomass distribution. The conditions compared were (I) randomized multiple families (inter-family) planted at low density (0.25 × 0.12 m), (II) inter-family groups at high density (0.12 × 0.06 m), and (III) single-family parcels (intra-family) at high density (0.12 × 0.06 m), established in a common garden test under a split plot design with four replicates and four plants per replicate. At 10 months of being established, two replicates were harvested. Differences were detected between competitive conditions for all measured variables on production, biomass distribution, survival and growth architecture (P ≤ 0.05). At family level we identified individual growth strategies which resemble the three classic ideotypes (isolation, competition and crop), as well as genotypes that adjusted their growth depending on the competitive environment. These results reflect the importance of environmental and genotype selection in order to increase adaptation and productivity at breeding programs.