Apart from the N0 treatment in 2013, the total root length decreased in all other treatments after the beginning of silking in both years (Fig. 2). On average, the root length decreased by 27% in the N0 treatment, to a smaller extent compared to that in N120 (52%) and N240 (51%) (Table 3). In 2013, the total root length in the N0 treatment increased from 10 to 30 DAS, and then decreased thereafter (Fig. 2). At maturity, the root length in N0 was only 12% less than that silking. In this year, the total root length in the N240 treatment from 10 to 20 DAS also significantly increased, but to a much small extent (Fig. 2).