Abstract:

The cherry tomato (Lycopersicon esculentum var. cerasiforme) was used to investigate vitamin C (VC) content,
ascorbic acid oxidase (AAO), ascorbate peroxidase (APX) and polyphenol oxidase (PPO) activities under greenhouse and
outdoor condition with Lou soil or loessial soil during the fruiting period. The results showed that from early to later fruiting
stages, the VC content increased firstly then decreased, whereas the AAO activity exhibited the opposite trend. Meanwhile,
APX activity showed an increasing trend while PPO activity presented a decreasing trend. The VC content was higher in
cherry tomatoes from Lou soil than those from loessial soil under the same cultivation condition and it was better in outdoor
than in greenhouse with the same type of soil. The vitamin C content was significantly higher in outdoor Lou soil cultivation
than other treatments during the growth seasons. A significant difference between outdoor Lou soil culture and other
treatments was observed (P < 0.05). However, AAO activity was the highest in greenhouse loessial soil treatment and the
lowest in outdoor Lou soil treatment. The ascorbate peroxidase activity followed the order of outdoor Lou soil > greenhouse
Lou soil > greenhouse loessial soil > outdoor loessial soil during the early fruiting stage, while followed the order outdoor
Lou soil > outdoor loessial soil > greenhouse Lou soil > greenhouse loessial soil during the full fruiting stage and later
fruiting stage. PPO activity was the highest in outdoor loessial soil treatment and outdoor Lou soil treatment took second place.
Correlation analysis indicated that the activities of AAO and PPO were negatively correlated with ascorbic acid content. Therefore,
outdoor Lou soil was optimum treatment for preserving high ascorbic acid content and low AAO, APX and PPO activities.

Key words: cherry tomato, ascorbic acid (VC), ascorbate oxidase (AAO), ascorbate peroxidase (APX), polyphenol oxidase (PPO)