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

<p>Rice plants (<i>cv.</i> 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.</p><p>Notes: Significant differences (<i>P</i><5%) between N supplies or varieties were indicated by different lowercase letters or different uppercase letters, respectively. <i>A</i>, g_s, g_m, 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.