Análise da dormência e tolerância ao frio de macieiras cultivadas em condições de inverno ameno

Abstract

The present research addressed to characterize dormancy dynamics and freezing tolerance, thus testing the efficiency of mathematical prediction models of phenology of Eva, Fuji Suprema and Galaxy apple trees. Shoots and spurs were collected between March and October 2012 and 2017, in a commercial orchard in Palmas municipality, Paraná, Brazil. The following tests were performed: Tabuenca in order to establish the final endodormancy in floral (mixed) buds; one-bud cutting test to determine dormancy dynamics in vegetative buds and; the freezing test by LT50 aiming to estimate the level of cold hardiness and its correlation with dormancy. Fifteen mathematical prediction models of phenology from the hourly temperature were tested. The phenology prediction models were inferior or as predictive as the historical average of phenology. The dynamics modeling in the form of a linear equation with breakpoint presented an attractor parameter (Bp) which offset for climate alterations and induced the release dormancy dates near the historical average. The dormancy was related to plant protection against frost damage, also the occurrence of shallow dormancy made the vegetal more susceptible to damage.