Table 1.

Effect of low temperature on the regulation of PPO activity in leaf of Pui vegetable. The plants were exposed to 8 °C for 24 h, 48 h and 72 h in the cold chamber. After the treatments, the plants were immediately removed from the chamber and sampling of leaf was performed. For assay of PPO activity, 10 mM concentration of catechol was used as a substrate of the enzyme. Control plants were similarly used except giving low temperature exposure.

Treatments	Polyphenol oxidase (PPO) activity (Unit g−1 of leaf)
Control	251.68 ± 75.97
24 h	395.42 ± 57.77A
Control	1198.71 ± 187.98
48 h	2122.33 ± 205.70B
Control	2615.21 ± 281.47
72 h	3168.25 ± 180.81A

The results are means of ± SE for three values in each group.

^Ap < 0.05 versus respective control.

^Bp < 0.01 versus respective control.