Fig 6. Average changes in root dry weight at silking of maize from China (a, high planting density; b, water stress; c, N deficiency) and US Corn Belt (d, high planting density; e, water stress; f, N deficiency) in response to various stresses.

The data derived from individual experiments from China and US Corn Belt were used. The values above columns indicate the reduction (%) under stresses compared with the optimum conditions. 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.