Effects of N supply level on leaf photosynthesis in rice seedlings.

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 more than 20 individual chloroplasts for their length and thickness, and 5 individual plants for other variables.Notes: Significant differences (PA, gs, gm, N, Rubisco and PNUE represent leaf photosynthetic rate, stomatal conductance to CO2, mesophyll conductance to CO2, leaf nitrogen content, leaf Rubisco content, photosynthetic N-use efficiency, respectively.