SLA was recorded on ten randomly selected plants in each plot. Four leaflets of the second fully expanded leaf from the top of main stems were detached and kept in plastic bags until leaf area was recorded using a leaf area meter (ACC-400, Hayashi Denken). The leaves were dried in an oven at 80 8C for 48 h before recording dry weight. SLA was calculated as the ratio of leaf area to leaf dry weight (cm2 g