Effects of soil compaction on morphology, biomass and architecture variables on black pine (Pinus nigra) in greenhouse situations

Increasing soil strength would adversely affect the seedling morphology (size) and growth (biomass) by changing the above- and below-ground patterns. In this research, the effects of soil compaction were explored in a loam to clay-loam textured soil with optimal conditions of water on a continuous scale on growth responses of the Pinus nigra in four intensity treatments of soil compaction (the lowest intensity of compaction, low, moderate, and high intensities of compaction). Results showed that the above- and below-ground metrics of seedling size (i.e., stem length and diameter, leaf length, main root length and diameter, and lateral root length) and biomass (i.e., total, shoot, and total root) were negatively affected by soil compaction. Seedling sizes and growth parameters responded non-linearly by increasing soil strength. Increasing soil strength changed the above- and below-ground biomass allocation patterns (i.e., root mass ratio, root: shoot ratio, specific root length) resulting in unchanged seedling architecture. It is concluded that growth of roots and heights of black pine seedlings are restricted with any increase in soil strength. The increasing soil compaction causes significant differential growth allocation patterns to above- and below-ground portions resulting in architectural changes to the seedlings.