Abstract: The total phenolic content and activities of phenylalanine ammonia-lysae (PAL), polyphenol oxidase (PPO), peroxidase (POD) in fruits of ‘Ninghaibai' loquat(Eriobotrya japonica Lindl) cultivated in open air, bagging and greenhouse were measured in winter and spring. The results showed that total phenolic content in fruit cultivated in open air condition was significantly higher than those in bagging and greenhouse conditions in winter and decreased with the coming of spring. However, the total phenolic content in fruit cultivated in bagging and greenhouse conditions almost unchanged between winter and spring. The PAL activities of fruits in all treatments in winter were much higher than those in spring, and the activity in open air was higher than those in bagging and greenhouse. Activity of PPO in fruit of open air was the lowest in winter; the highest was in bagging both in winter and spring. The activity of POD in open air was higher than those in bagging and greenhouse in winter. In spring, the activities of POD decreased. These results suggested that the accumulation and metabolism of phenolic compounds might be related to the resistance of freeze in loquat fruit in winter.

Key words: loquat, young fruit, phenolic compounds, PPO, PAL, POD