Heterogeneidade da brotação e da floração do pessegueiro em condições de inverno ameno

Abstract

The peach tree is a perennial species of economic importance in Brazil, however, not all cultivars are adapted to Brazilian growing conditions. The cultivars better adapt to the subtropical climate are those with low chilling requirement. However, depending on the growing size, frost damage may occur. The aim of this work was to study the dormancy dynamics and the physiological state of vegetative and floral buds of two peach cultivars growing in mild winter conditions. Long shoots bearing, with vegetative and floral buds, were regularly collected during the dormant period os the trees, in 2017. The dormant state in vegetative buds was evaluated by the singlenode cutting test and in floral buds by the Tabuenca’s test. Single-node cutting was carried out under forcing conditions at 25 °C and 16 hours of photoperiod, until the buds reach the green tip (GT) stage, to determine the mean time of budbreak (MTB). The Tabuenca’s Test consiste in determining the fresh and dry mass of the floral buds before and after a period of forcing of 7 days at 25 ºC. The endormancy release was based on significant dry weight changes. The dormancy dynamics of vegetative buds and, consequently, sprouting heterogeneity is linked to the temperature oscillations that occur during the rest period. Mild winter induces shalow endodormance and quick transition between endodormance and ecodormence. 'BRS Kampai' presented MTB spatial heterogeneity, which resulted in erratic sprouting, a fact not observed in 'BRS Mandinho', whose sprouting was more homogeneous. On the other hand, 'BRS Mandinho' presented greater erratismo of blooming, demonstrating that not always cultivars of low chilling requirement has greater blooson homogeneity. The Tabuenca’s test was again satisfactory to identify the end of endodormence phase and the onset of ecodormence, by the significant change of the dry weight of the floral primordium in forcing condition.