Effects of row spacing on photosynthetic rate (<i>P</i>_N) of flag (<i>A</i>,<i>B</i>,<i>C</i>,<i>D</i>), penultimate (<i>E</i>,<i>F</i>,<i>G</i>,<i>H</i>) and third leaves (<i>I</i>,<i>J</i>,<i>K</i>,<i>L</i>) of two spike types of wheat under high planting density over a two-year period (2011 and 2012).

<p>R₀, R₁, R₂ and R₃ refer to 5-cm row spacing, 15-cm row spacing, 25-cm row spacing and 35-cm row spacing, respectively. Data are means ± standard error (SE; n = 3). Vertical bars indicate the SE.