Fractal analysis for root growth of plant seedlings under doubled CO2 concentration

Fractal geometry was applied and box dimension was used as an indicator to analyze the effects of doubled CO₂ concentration on the root growth of plant seedlings. Results showed that doubled CO₂ concentration displayed different effects on root branching characteristics of C₃ and C₄ plants. There was an obvious increase of root branches in spring wheat while there were no significant effects on roots of sweet sorghum. In different soil layers, root branching of spring wheat was stimulated and this promotion was most significant in the second layer (10–20 cm), which denoted that elevated CO₂ altered the root branching pattern. That means higher CO₂ concentration influences not only root growth but also its differentiation and development.