Fig 5. Comparisons of root dry weight at silking (silking RDW) (a) from 217 unpaired data and root/shoot ratio at silking (b) from 100 unpaired data of maize grown in US corn belt and five Chinese major maize planting regions (Regions I to V).

Regions (I to V) were classified according to geographical (climatic) distinctions and soil types in China (S1 Fig). The solid line and square within the box represents the median and mean values of all data, the top and bottom edges of the box represent 75 and 25 percentiles and the top and bottom bars represent 95 and 5 percentiles of all data, respectively.