The
energy efficiency was highest under 300 mol m−2 s−1.
When photosynthetic photon flux density (PPFD)
increased from 50 to 550 mol m−2 s−1, a decrease in the specific leaf area (SLA) was observed.
Under 300
and 450 mol m−2 s−1, the thickness of leaves, palisade parenchyma and spongy parenchyma were the
bigger, and the stomatal frequency and stomatal area per unit leaf area were also higher.