Growth variables of rice seedlings grown at different N supplies.

Rice plants (cv. Shanyou 63 and Yangdao 6) were supplied with N at three different levels (low: 20 mg L−1 N, intermediate: 40 mg L−1 N, and high: 100 mg L−1 N). Data are means ± SD of 5 individual plants. Variables were determined 40 days after the start of treatment. Notes: Significant differences (P<5%) between N supplies or varieties were indicated by different lowercase letters or different uppercase letters, respectively. RMR, SCMR and LMR represent root mass ratio, leaf sheath and culm mass ratio and leaf mass ratio, respectively. They were calculated as the ratio of separate dry mass to whole plant dry mass. SLW represents specific leaf weight, and was calculated as the ratio of leaf fresh weight to leaf area.