The change in root length of the early developed nodal roots compared to the late-developed nodal roots was investigated in more detail (Fig. 2). The reduction in root length was greater in early developed nodal roots than in late-developed nodal roots. Across years and N treatments, the root length of early developed nodal roots decreased by 44 to 71% and that of late developed nodal roots decreased by 8 to 43% (Table 3). Compared with the N120 treatment, the N240 treatment did not delay the reduction in root length of both the early- and the late-developed nodal roots (Fig. 2, Table 3).