EFFECT OF ETHYLENE ON SENESCENCE AND REGULATION OF ETHYLENE BIOSYNTHESIS IN STORED BROCCOLI FLOWER BUDS - EFFECT OF TEMPERATURE

The role of ethylene on senescence and regulation of ethylene biosynthesis were assessed during storage of broccoli florets (Brassica oleracea L., Italica group, cv Green Valiant) at room temperature and at 1-degrees-C. The florets were stored in the dark under air containing: 0 (control), 1 and 10 ppm ethylene at 25-degrees-C and 0 (control), 10 and 100 ppm ethylene at 1-degrees-C. Ethylene accelerated chlorophyll loss and the effect increased with higher ethylene concentration. This effect was greatly reduced at 1-degrees-C. Ethylene accelerated the climacteric-like increase in respiration, endogenous ethylene and ethylene forming enzyme (EFE) activity at 25-degrees-C. Contents in 1-aminocyclopropane-1-carboxylic acid (ACC) were not changed. Respiration, ethylene production and EFE activity greatly decreased at 1-degrees-C, but ACC content increased. Exogenous ethylene had no effect on these reactions. Our results suggest only little influence of ethylene in the preservation of broccoli florets at optimal storage temperature.