Abstract

Oncidium varicosum is an orchid largely distributed in South America, whose inflorescences with bright yellow flowers are of rare beauty. One of the objectives of the postharvest physiology of flowers is the study of the factors related with the quality loss of cut flowers. The ethylene performs a very important function on the senescence of flowers because it induces abscission of flowers buds and open flowers causing precocious wilting and loss of quality. The sensitivity to ethylene has been reported as variable in function of floral species, exposition period and regulator concentration. The present research evaluated the postharvest of cut inflorescences of O. varicosum ‘Samurai’, after application of ethylene (Ethrel: 1, 10 and 100 mL L^-1). The experiment was performed as complete randomized design with factorial scheme composed of two factors: four postharvest treatments and four dates of evaluation. The inflorescences were maintained in the refrigerated ambient. The results demonstrated that the exposition to ethylene caused physiological alterations such as reduction of relative water content of the flowers, decrease of the soluble carbohydrates contents of the petals, increase of the respiration rate and flowers abscission. The concentration of 100 mL L ^-1 of Ethrel reduced the decorative life of flowers in seven days in relation to the control without product application. while at 1 μL L^-1, the flowers presented lower sensitivity to product, with results similar to the control.

Key words: Postharvest physiology, orchids, carbohydrates, respiratory rate.