2.3.3. Determination of chlorophyll concentrations of leaves
Chlorophyll was extracted from the leaves (fully expanded, exposed) of 10 plants at a similar position within each treatment. Leaves were weighed out in 0.1 g (fresh weight, W), and samples were ground in a mortar. The optical density was measured with a UV-1200 spectrophotometer (SP-75, Shanghai spectrum instruments co., LTD, China) at 663 nm (OD663) for chlorophyll a (Chl. a), and 645 nm (OD645) for chlorophyll b (Chl. b) (Hartmut, 1983; Li et al., 2013).