Eficácia de soluções para a conservação pós-colheita de inflorescências cortadas de Oncidium varicosum (Orchidaceae)

Abstract

The orchid Oncidium varicosum is a tropical plant with significant commercial value due to the beauty of its yellow inflorescences. Several authors have observed a reduction in the water content of cut flowers, consequently, wilting and senescence of petals are the main reasons for the termination of the decorative life of cut flowers. In this research, we studied the effects of several chemical compounds on the postharvest life of cut inflorescences of Oncidium varicosum ‘Samurai’. These chemicals are as follows: sucrose (5%) plus 8-hidroxiquinoline citrate (8-HQC) (100 mg L-1) plus silver nitrate (AgNO3) (50 mg L-1); sucrose (5%) plus citric acid (75 mg L-1); quaternary ammonia at 30% (50 mg L-1); and sucrose (5%) plus quaternary ammonia at 30% (50 mg L-1). The highest values for average of relative water content, reducing carbohydrates and soluble sugars were recorded in the flowers treated with the sucrose (5%) plus 8-HQC (100 mg L-1) plus AgNO3 (50 mg L-1) solution. A reduction in color intensity occurred at 12 days postharvest in all treatments and the carotenoid content was reduced to the greatest extent in flowers maintained in distilled water. The lowest numbers of open flowers were observed at 12 and 15 days in the distilled water and quaternary ammonium treatments, being that the others treatments favored the anthesis. The Oncidium inflorescences treated with sucrose plus HQC plus AgNO3 demonstrated a higher number of open flowers and reached the longest longevity (22 days).