Age-related changes in root dynamics of a novel perennial grain crop

Abstract

Background: Standing root biomass stocks are larger in the perennial grain intermediate wheatgrass (IWG; Thinopyrum intermedium [Host] Barkworth and Dewey) than annual spring wheat (Triticum aestivum L.). However, previous studies have not separated root growth from root decomposition, which presents a significant gap in our understanding of how roots can contribute to soil organic carbon (C) accrual or other soil properties through time.

Methods: We used paired sequential coring and root ingrowth cores to measure standing root stock, new root production, root decomposition, and decomposed root C and N from 0 to 15 cm soil depth of 1-year-old IWG (IWG-1), 2-year-old IWG (IWG-2), and annual spring wheat.

Results: Standing root stock was 3.2–6.5 and 6.3–9.9 times higher in IWG-1 and IWG-2 than wheat. Total root production was 1.7 times greater in IWG-1 than IWG-2. Conversely, root decomposition almost doubled from 1.39 to 2.43 kgm⁻³ between IWG-1 and IWG-2.

Conclusions: In IWG, decreased root production and increased root decomposition with stand age suggest a change in growth strategy that could reduce the contribution of root-derived C to stabilized soil C pools as IWG stands age.

Key words： intermediate wheatgrass; Kernza; perennial grain; root decomposition; root growth; root ingrowth cores; root–soil interactions