Root system-based limits to agricultural productivity and efficiency: the farming systems context

Abstract

Background There has been renewed global interest in both genetic and management strategies to improve root system function in order to improve agricultural productivity and minimize environmental damage. Improving root system capture of water and nutrients is an obvious strategy, yet few studies consider the important interactions between the genetic improvements proposed, and crop management at a system scale that will influence likely success.Scope To exemplify these interactions, the contrasting cereal-based farming systems of Denmark and Australia were used, where the improved uptake of water and nitrogen from deeper soil layers has been proposed to improve productivity and environmental outcomes in both systems. The analysis showed that water and nitrogen availability, especially in deeper layers (>1 m), was significantly affected by the preceding crops and management, and likely to interact strongly with deeper rooting as a specific trait of interest.Conclusions In the semi-arid Australian environment, grain yield impacts from storage and uptake of water from depth (>1 m) could be influenced to a stronger degree by preceding crop choice (0Á42 t ha ). Matching of deep-rooted genotypes to management provided the greatest improvements related to deep water capture. In the wetter environment of Denmark, reduced leaching of N was the focus. Here the amount of N moving below the root zone was also influenced by previous crop choice or cover crop management (effects up to 85 kg N ha -1 ) and wheat crop sowing date (up to 45 kg ha -1 ), effects which over-ride the effects of differences in rooting depth among genotypes. These examples highlight the need to understand the farming system context and important G Â E Â M interactions in studies on proposed genetic improvements to root systems for improved productivity or environmental outcomes.

Root phenotypes for improved nutrient capture: an underexploited opportunity for global agriculture

“…Multiple synergies and antagonisms exist among axial root phenotypes of bean for capture of P and N, resulting in multiple integrated phenotypes that co‐optimize capture of these two resources (Rangarajan et al ., ). Fitness landscapes will also be influenced by management scenarios (Thorup‐Kristensen & Kirkegaard, ). The substantial interactions of root phenes with each other and the environment means that the fitness landscape of integrated root phenotypes against the multidimensional array of environmental and internal factors is highly complex.…”

Belowground solutions to global challenges: special issue from the 9th symposium of the International Society of Root Research

“…This study joins a growing literature that suggests that crop selection and breeding for root traits must be informed by the management practices of the target farming system (e.g. Thorup-Kristensen and Kirkegaard 2016).…”

Digging Deeper for Agricultural Resources, the Value of Deep Rooting

“…Increased rooting depth of crops in current cropping systems may be achieved through a range of approaches, by plant breeding [39], or by various changes in crop management and optimization of crop rotations [40]. In the longer term, more radical improvements can be achieved by changing the crop species grown from annual to perennial, by intercropping shallow rooted crops with deeper rooted species, or by promoting agroforestry systems to ensure exploitation of deeper soil layers beneath the shallow rooted crops.…”