01796naa a2200205 a 450000100080000000500110000800800410001910000200006024500840008026000090016452012330017365000090140665000130141570000170142870000190144570000200146470000200148470000190150477300670152321529222023-04-03       2023    bl uuuu     u00u1 u    #d1 aCROSA, C. F. R.  aBudbreak of pecan cultivars subject to artificial chill.h[electronic resource]  c2023  aChill is a limiting factor in commercial production of temperate fruit due to their dormancy mechanism. Thus, knowledge of chill requirements of cultivars is important to reach successful production. This study aimed at evaluating responses given by different pecan cultivars subject to artificial chill. Pecan branches were collected from twelve 9-yearold cultivars ? Success, Shoshoni, Farley, Elliott, Mohawk, Jackson, Desirable, Barton, Importada, Shawnee, Choctaw and Melhorada ? in two orchards located in Canguçu, Rio Grande do Sul (RS) state, Brazil, in 2017 and 2018. Treatments consisted in exposing branches to 0, 250, 500, 750 and 1,000 chill hours in a cold chamber (4.0 ± 0.5 °C) and then taking them to the germination chamber (25 ± 0.5 °C and photoperiod of 16 hours of light) until the end of the evaluations. Final budbreak rate (FBR) of every cultivar and the number of days required to reach 50% of budbreak (DD50%) were evaluated. Chill required by cultivars to start budbreak varied in both years under evaluation. Both FBR and DD50 were higher in 2017 than in 2018. Due to high variation in FBR and DD50, chill requirements of pecan cultivars could not be clearly determined by the biological method.  aFrio  aNoz Peca1 aMARCO, R. DE1 aBARRETO, C. F.1 aSOUZA, R. S. de1 aYAMAMOTO, R. R.1 aMARTINS, C. R.  tRevista Ceres, Viçosagv. 70, n. 1, p. 42-50, jan./feb. 2023.