Maize root system phenotypes for efficient uptake of nitrogen and high yields

Identifying maize genotypes with a high capacity for nitrogen uptake without yield penalty is relevant to breeding maize for sustainable production systems with reduced nitrogen input. Identifying root system phenotypes that may achieve this is difficult in the field. We applied an established functional-structural plant (FSP) model. We first identified seven important root traits that give either high yield or high N uptake at a wide range of soil N levels, and determined which trait values give both high N uptake and high yield. After that, data from field experiments covering 12 maize cultivars released in China between the 1970s and the 2010s were used to evaluate the model results. In line with observed data, our simulated results demonstrated trade-offs exist in root traits between high yield and high N uptake, specifically in root sink strength for carbon, root length density, root length, and root-to-leaf biomass partitioning. We identified two root system phenotypes that give both high yield and high N-uptake. We show low root biomass with high root length density at 15 cm to 45 cm depth allowed maize to combine high yield and high N uptake. Our study demonstrates that cluster analysis of FSP modelling results can be used to identify improved root system phenotypes across a wide range of environments, which is useful information when defining targets for breeding.