Seasonal Changes of Peroxidase, Polyphenol Oxidase Enzyme Activity and Phenol Content During and after Rest in Pistachio (Pistacia vera L.) Flower Buds

Abstract

This experiment was conducted to determine peroxidase (POD) and polyphenol oxidase(PPO) enzyme activity in flower buds of 'Kalle-Guchi', 'Owhadi', 'Ahmad-Aghaei' and 'Akbari' pistachio during and after rest. The activity of the enzymes showed a typical seasonal pattern in all the pistachio cultivars. The activity of POD increased in December and February and decreased in January and March in 'Kalle-Ghuchi', 'Owhadi' and 'Ahmad-Aghaei' but, in 'Akbari' increased from November to January and then, decreased to March. The activity of PPO decreased from November to February and increased in March in 'Kalle-Ghuchi', but PPO activity was low in November and increased in December, then decreased to a minimum in January and February and again reached its maximum level in March in 'Owhadi', 'Ahmad-Aghaei' and 'Akbari'. The activity of both enzymes from bud swell stage to post bloom stage, decreased in all cultivars. Their activity was highest in 'Kalle-Ghuchi' and lowest in 'Akbari' and intermediate in 'Owhadi' and 'Ahmad-Aghaei' during dormant season, but after rest, a similar pattern was found for flower buds although, there were no significant differences in the enzyme activity in all pistachio cultivars. In the present study, phenol contents increased from November to January and then, decreased to March in 'Kalle-Ghuchi', but in other cultivars, that increased to a maximum in February and decreased in March. Total phenol content for all of the pistachio cultivars decreased from bud swell to post bloom stage.