Root phenotypes for improved nitrogen capture

Abstract

Background Suboptimal nitrogen availability is a primary constraint for crop production in low-input agroecosystems, while nitrogen fertilization is a primary contributor to the energy, economic, and environmental costs of crop production in high-input agroecosystems. In this article we consider avenues to develop crops with improved nitrogen capture and reduced requirement for nitrogen fertilizer. Scope Intraspecific variation for an array of root phenotypes has been associated with improved nitrogen capture in cereal crops, including architectural phenotypes that colocalize root foraging with nitrogen availability in the soil; anatomical phenotypes that reduce the metabolic costs of soil exploration, improve penetration of hard soil, and exploit the rhizosphere; subcellular phenotypes that reduce the nitrogen requirement of plant tissue; molecular phenotypes exhibiting optimized nitrate uptake kinetics; and rhizosphere phenotypes that optimize associations with the rhizosphere microbiome. For each of these topics we provide examples of root phenotypes which merit attention as potential selection targets for crop improvement. Several cross-cutting issues are addressed including the importance of soil hydrology and impedance, phenotypic plasticity, integrated phenotypes, in silico modeling, and breeding strategies using high throughput phenotyping for co-optimization of multiple phenes. Conclusions Substantial phenotypic variation exists in crop germplasm for an array of root phenotypes that improve nitrogen capture. Although this topic merits greater research attention than it currently receives, we have adequate understanding and tools to develop crops with improved nitrogen capture. Root phenotypes are underutilized yet attractive breeding targets for the development of the nitrogen efficient crops urgently needed in global agriculture.

Genetic control of root morphology in response to nitrogen across rapeseed diversity

“…Redesigning root system architecture holds the potential to sustain yield and reduce the negative environmental impact of mineral N fertilization. Whether the soil is N-poor or rich, a large root system would ensure efficient N capture (Louvieaux et al, 2018;Lynch et al, 2023). Great broad sense heritability values for root morphological traits, as well as important genotypic effects, were noted (Table S4).…”

“…In arable soils, nitrate is prone to leaching because it is repelled by colloids. A deep and branched crop root system that explores a large soil volume may prevent nitrate leaching (Thorup-Kristensen & Kirkegaard, 2016;Huang et al, 2023a;Lynch et al, 2023).…”

The pore‐rhizosheath shapes maize root architecture by enhancing root distribution in macropores

“…Secondly, the growth angle of seminal roots was strongly determined by the genetics rather than soil conditions. Maize seminal roots are developed from embryos, and have sufficient sources of nutrients for growth in the seedling stage (Fusseder, 1987;Lynch et al, 2023).…”

Oxygen and Nitrogen Vacancies in a BiOBr/g-C3N4 Heterojunction for Sustainable Solar Ammonia Fertilizer Synthesis

“…Crops such as rice, wheat, corn, and soybeans are examples of nitrogen-requiring crops that are widely cultivated around the world to meet the global demand for food and agricultural products . Efficient nitrogen fertilizer use is essential to minimize environmental impact while meeting the nutritional needs of these crops; it is vital for optimizing agricultural practices, enhancing crop yields, and ensuring food security …”