Cheng et al. (2007) found that the total root length, density, surface area, and biomass were significantlyhigher in rice cultivars which have higher NUE than those with low NUE and therefore could be used as reliable indicators in high NUE rice cultivar selection.
Ye et al. (2010) compared the rice cultivars with different NUE and found that the cultivars with high NUE had higher total root length, surface area, and amount of root apexes than those with low NUE at the full heading stage.