The relationship between individual root anatomy and fine root system development in blueberry seedlings: dominance of diarch roots in initial root systems

: Heterogeneity of individual root traits (heterorhizy) is thought to be one of the most important mechanisms that maintain the functional gradients in fine root systems. It is necessary to know heterorhizy and its relation to the root system architecture in seedlings, because it is the initial form of fine root development. Herein, we investi gated individual root traits and the root system architecture of blueberry seedlings by using the protoxylem grouping. Most individual roots were diarch but some laterals were monarch. Compared to the monarch, the diarch roots had significantly larger diameters and tissues, and over half of them exhibited secondary growth. In other words, frameworks of the blueberry seedlings were diarch, although those of cuttings had been at least triarch as seen in our previous study. The employment of diarch frameworks may optimize investment for root system expansion of blueberry seedlings. Our results imply ontogenetic dynamics of heterorhizy in blueberries.