Chilling requirement of four peach cultivars estimated by changes in flower bud weights

Abstract

Chilling requirement of four peach cultivars estimated by changes in flower bud weights 1The adaptation of temperate fruit crops is a challenge being increased by the global warming. Chilling requirement is a key factor for adaptation. The objective of this study was to estimate the chilling requirement of peach cultivars BRS Bonão, Esmeralda, Granada and Eragil, using the Tabuenca test. Chilling accumulation was computed using four different chilling hour (d+ 7.2 ºC and d+ 11 ºC) models; and chill units using the Low Chill model and the Taiwan model. The fresh bud weight and bud water contents were also evaluated. The Tabuenca test (based on differences in bud´s dry weight) showed a fairly good efficiency for estimating the end of dormancy in peach. However, under mild winter conditions, it is better to use fresh bud weights. Either one of three chilling accumulation computation models (temperature d+ 7.2 °C, d+ 11°C, or Taiwan model) is suitable to classify comparatively different cultivars, but none is accurate enough to conclude on the adaptation of a given cultivar to a specific site. Using hours of temperatures d+ 11 ºC: 'BRS Bonão' needed around 180 hours for dormancy release; 'Esmeralda' around 250 hours; 'Granada' between 300 and 400 hours, and 'Eragil' more than 500 hours.