Root growth phenology, anatomy, and morphology among root orders in Vaccinium macrocarpon Ait.

Abstract

Understanding the mechanisms controlling plant growth is essential in order to maintain and increase productivity in managed ecosystems. However, the lack of information on below-ground growth compared with above-ground growth limits our ability to adjust crop management practices under changing climate conditions. This study examines seasonal fine-root growth and its spatial distribution through the soil profile across the growing season, and the anatomical and morphological traits of roots according to their branching order in Vaccinium macrocarpon Ait. Root production followed a unimodal curve, with one marked flush of root growth starting at bloom, with a peak at the end of fruit maturation. Root vertical distribution concentrated in the upper 5 cm of soil depth, accounting for over 50% of new roots produced during the study. Root anatomy and morphology were related to root function, as the first three root orders had intact cortex and epidermis and high mycorrhizal colonization, indicative of absorptive function, while orders ranking fifth and higher had secondary development and the presence of a cambium cork layer, indicative of translocation. Our study highlights the importance of examining the timing of root growth and root traits by root order, and its implications for the timing of fertilization and other practices in managed ecosystems.