Table 3.

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, 200 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	4490.94 ± 294.41
24 h	5273.96 ± 240.33A
Control	4232.43 ± 111.46
48 h	5119.86 ± 146.11B
Control	4433.96 ± 56.60
72 h	5548.87 ± 181.12B

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

^Ap < 0.1 versus respective control.

^Bp < 0.05 versus respective control.