Fig. 3
Light intensity dependence of photosynthetic quantum yields of PSI [Y(I)] and PSII [(Y(II)] in leaves of alfalfa seedlings with or without apical buds. Five treatments in the seedlings with apical buds are as Fig.2, and seedlings without apical buds are grown in 1.5 mM Ca(NO3)2 medium (pH 4.5) and treated with or without spraying IAA (pH 4.5-IAA, pH 4.5 + IAA), 100 μM AlCl3 with or without spraying IAA (pH 4.5 + Al-IAA, pH 4.5 + Al + IAA) and 100 μM AlCl3 and 50 μM ZnCl2 with or without spraying IAA (pH 4.5 + Al + Zn-IAA, pH 4.5 + Al + Zn + IAA). The Y(I) (a) and Y(II) (b) were estimated from seedlings with apical buds, and Y(I) (c) and Y(II) (d) were estimated from seedlings without apical buds on day 3. At least 6 different leaves from different seedlings were used for each treatment and data are means ± SE of three replicates. Bars with different letters indicate significant difference at P < 0.05 (Leas significant difference test)