Antioxidant Defencive Response of Ray Florets Underuncutand Cut Conditions in Cosmos bipinnatus Sonata Pink Series

Various parameters for the study of antioxidant defensive response such as total phenols, activities of polyphenol oxidase, peroxidase, catalase and IAA oxidase were studied from the petals (ray florets) of flowers of Cosmos bipinnatus Cav. Sonata Pink series under uncut (flowers that remain attached to the plant) and cut (post-harvest) conditions after a regular interval of 24 hours from the time flowers opened or harvested till the end of the petal life under corresponding conditions. The total phenol content under cut conditions was found to be more as compared to that under uncut conditions. The polyphenol activity under cut conditions was found to be less than the activity under uncut conditions which supports more amount of total phenols under these conditions. The peroxidase and catalase activity under cut conditions showed increase during senescent stage. This increase is an indicative of increased production of Reactive Oxygen Species and the flower is trying to reduce oxidative damage as well as suggests removal of free radical production. The activity of IAA oxidase under cut conditions was always less as compared to the uncut conditions suggesting lower levels of IAA in uncut flowers which possibly lead to the production of ethylene. This suggests that the antioxidant defense of the flowers under cut conditions was better as compared to that of the flowers under uncut conditions and this is why the cut flowers managed to have more shelf life as compared to the flowers under uncut conditions.