Análises biológicas e bioquímicas na dinâmica da dormência de macieiras em Palmas – PR

Abstract

The present study aimed to characterize the dormancy dynamics and the variation of carbohydrates and other shoots constituents of apple tree with low ('Eva') and high chilling requirement ('Fuji Suprema' and 'Galaxy'), under increasing cold levels or over the period of dormancy in the field. Bearing shoots and spurs were collected between March until October 2012 and 2013 in a commercial orchard in Palmas-PR. Tabuenca (1964) biological test and one bud cuttings test were performed. Simultaneously, one-year-old shoots wood, in the basal and apical portions, were reserved for soluble proteins, alpha-amylase activity, total soluble sugars, reducing and non-reducing sugars, starch and water content analysis. The Tabuenca test (1964) can be applied in subtropical climate to estimate the end endodormancy. Among the cultivars, 'Eva' has lower chilling requirement than 'Fuji Suprema' and 'Galaxy', which were equivalent. The apple tree budbreak gradient occurs along the shoot, with greater capacity for sprouting in the lateral buds of the apex. However in high exposure to cold temperature this gradient is no longer significant. The shoots apical portion present higher levels of soluble proteins, alpha-amylase activity, total soluble sugars, reducing and non-reducing sugars and starch than the basal portion. With the advancement of cold exposure the alpha-amylase activity increased. The occurrence of irregular chilling accumulation promotes starch resynthesis, water content decrease and sprouting delay.