Genotypic variations appear in fine root morphological traits of Cryptomeria japonica trees grown in a common garden

Abstract

Aims Fine root morphological traits regulate the belowground resource acquisition strategies of trees. However, genotypic variations isolated from environmental variations within tree species remain unclear. Thus, this study aimed to clarify the effects of genotypic variations on the fine root morphology of three types of Japanese cedar (Cryptomeria japonica), which were derived from different provenances but were grown in a common garden.Methods In the three geographically different provenances of C. japonica stands (Yanase, Yoshino, and Yaku), fine root morphological traits, such as root length and diameter and specific root length (SRL), were measured for each root up to the 4th branching order.Results Yaku cedar exhibited root traits distinct from the other provenances, such as growing longer and thinner roots in 1st root order to enhance root surface area. In addition, the SRL patterns with root orders and higher root tissue density suggested a resource conservation strategy corresponding to the low aboveground production of Yaku cedar. Yanase cedar demonstrated a significantly higher root branching ratio and specific root tips than the other provenances, indicating a strategy for investing resources in absorptive roots. Although Yoshino cedar had traits similar to that of Yanase cedar or intermediate between Yanase and Yaku cedars, high aboveground production may be achieved by nutrient acquisition with root exudates instead of absorptive root growth.Conclusion Genotypic variations appeared in fine root morphological traits of C. japonica trees, even when grown in the same environments, implying distinct resource acquisition strategies characterized by each provenance.