Fig. 1

ALA induced kinetic changes of chlorophyll content in tomato leaves within 96 h after imposition of low temperature. The tomato leaves treated with distilled water or 25 mg·L^− 1 ALA then exposed to normal condition (control and ALA) or low temperature (LT and LTA) 12 h later. The chlorophyll (Chl) content were measured when the low temperature started. Data are expressed as the mean ± standard error of three independent biological replicates. The experiments were repeated for three times. Different letters above the bars indicate a significant difference determined by one-way ANOVA with Tukey’s test (P < 0.05). Fw, fresh weight