Root Size and Root/Shoot Ratio at Silking
Nitrogen treatment had a significant effect on root length and root DW in both years. The N × sample date effect was significant in 2013 but not in 2011(Table 2). At the silking stage in 2011, the total root length was longer in the N0 treatment than in the N120 and N240 treatments (Fig. 2), but there was no difference in total root length between the N120 and N240 treatments. No difference was found in root DW at silking among the N treatments in this year. In 2013, total root length was similar in the N0 and N120 treatments, and both were higher than that in the N240 treatment at silking stage (Fig. 2). Total root DW was the higher in N0 treatment compared to N120 and N240 treatments at this stage (Fig. 3).