Abstract:

The effects of sucrose treatment on antioxidant activity and energy metabolism of broccoli florets were investigated. Broccoli florets were treated with MS solid medium including various concentrations（0，50，100，150，200 and 250 mmol · L^-1）of sucrose in dark for 3 d. The results showed the medium with 150 mmol · L^-1 of sucrose significantly inhibited the chlorophyll degradation，while the control group turned completely yellow. When compared to the control group，sucrose treatment restrained the increase of polyphenol oxidase（PPO）activity and the decrease of L-phenylalanine ammonia-lyase（PAL）activity. There were no remarkable differences in the increase of malondialdehyde（MDA）content between the sucrose-treated and control groups. Sucrose treatment maintain the energy metabolism by maintaining higher levels of ATP，ADP and energy charge（EC）and delaying the decline of Ca²⁺-ATPase activity in chloroplast and mitochondria. The declining of the vitamin C may not be the key to chlorophyll degradation.

Key words: broccoli, sucrose, antioxidant enzymes, energy metabolism