| Treatment | RI | RII | RIII | Mean |
| T1 = Control (no urea) | 30.1 | 33.2 | 38.6 | 33.9 |
| T2 = Recommended urea soil applied (130 kg・ha−1) | 61.1 | 63.6 | 64.2 | 63.0 |
| T3 = 1% urea at 35 days after sowing | 66.6 | 68.7 | 70.1 | 68.5 |
| T4 = 1% urea at 60 days after sowing | 62.5 | 65.0 | 65.7 | 64.4 |
| T5 = 1% urea at 85 days after sowing | 61.7 | 63.9 | 64.9 | 63.5 |