CHANGES OF ETHYLENE EVOLUTION, ACC CONTENT, ETHYLENE-FORMING ENZYME-ACTIVITY AND RESPIRATION IN FRUITS OF HIGHBUSH BLUEBERRY

We measured ethylene evolution, ACC content, ethylene forming enzyme ( EFE) activity, and respiration in highbush blueberry (Vaccinium corymb osum L.) from flowering to harvest to assess the role of ethylene in t he processes. Cultivars used were 'Collins' (early maturing), 'Berkele y' (mid-season), and 'Dixi' (late maturing). Ethylene evolution increa sed at both petal-fall and maturation stages, and was higher in the ea rly stage than in the late stage. Ethylene at petal fall was produced by the calyx and ovary parts, but not the corolla. This indicates that ethylene evolution in flowering is correlated with pollination or fer tilization or both. Ethylene evolution rate in the maturation stage wa s high between the blue pink (BP) peel color in 'Collins', and mature green (MG) stage in 'Berkeley', and green pink (GP) stage in 'Dixi'. E thylene evolution was higher for 'Collins' than for the others in both years and higher in 1995 than in 1994. The pattern of EFE activity wa s not similar to that of ethylene evolution except in 'Collins'. There fore, the correlation between ethylene evolution and EFE activity in t he maturation stage was different with each cultivar. Berry ACC conten t was high at GP stage in three cultivars before ethylene evolution in creased.