Optimisation of root traits to provide enhanced ecosystem services in agricultural systems: A focus on cover crops

Abstract

Roots are the interface between the plant and the soil and play a central role in multiple ecosystem processes. With intensification of agricultural practices, rhizosphere processes are being disrupted and are causing degradation of the physical, chemical and biotic properties of soil. However, cover crops, a group of plants that provide ecosystem services, can be utilised during fallow periods or used as an intercrop to restore soil health. The effectiveness of ecosystem services provided by cover crops varies widely as very little breeding has occurred in these species.Improvement of ecosystem service performance is rarely considered as a breeding trait due to the complexities and challenges of belowground evaluation. Advancements in root phenotyping and genetic tools are critical in accelerating ecosystem service improvement in cover crops. In this study, we provide an overview of the range of belowground ecosystem services provided by cover crop roots: (1) soil structural remediation, (2) capture of soil resources and (3) maintenance of the rhizosphere and building of organic matter content. Based on the ecosystem services described, we outline current and promising phenotyping technologies and breeding strategies in cover crops that can enhance agricultural sustainability through improvement of root traits.

Root phenotypes for the future

“…In addition to improving root traits in new varieties to improve their resilience to environmental stresses, future crops will also rely on other organisms to facilitate their field performance. In this issue, Griffiths et al (2022) review how cover crops are playing an increasingly important role to provide critical ecosystem services. These services include soil structural remediation, such as using tap‐rooted plants like forage radish to penetrate and break up compacted subsoil and leave soil biopores; capture of soil resources, where “catch” cover crops convert residual soil nutrients into plant biomass that will be released to later crops after cover crop termination; and improving organic content, through the release of root exudates which have a strong positive effect on soil carbon dynamics.…”

Plant root growth against a mechanical obstacle: the early growth response of a maize root facing an axial resistance is consistent with the Lockhart model

“…In the current context of climate change, the frequency of extreme wet/dry and freeze/thaw cycles can exacerbate the compaction of soils and increase their strength, thereby limiting crop yield [7]. As a consequence, breeding programmes for plant species of agronomic interest such as wheat, soybean, rice or maize have been developed in soil science and ecophysiology communities to identify which root traits give the better plant fitness in large strength soils [8,9]. In particular, some works focused on macroscopic traits such as the number of root axes or the root tortuosity in relation with soil strengths [10][11][12].…”

Microbe-assisted crop improvement: a sustainable weapon to restore holobiont functionality and resilience

“…Taken together these findings highlight the importance to enhance cover crop root traits selecting those able to enhance ecosystem services in the agricultural contexts as (near) future challenge for breeders. Even if increasingly attention were recently posed by several scientists, to date cover crops have been subjected only to minimal domestication and breeding selection with respect to cultivated crops [ 92 ]. However, in the frame of an holistic view about microbe-assisted improvement of crop (and agro-ecosystems) resilience, breeding programs, or the use of novel genetic tools able to exploit superior root traits of specific cover crops ( e.g.…”