caa a22 4500 445367202 CHVBK 20180317142934.0 cr unu---uuuuu 170323e20110501xx s 000 0 eng 10.1007/s00484-010-0352-y doi (NATIONALLICENCE)springer-10.1007/s00484-010-0352-y A global analysis of the comparability of winter chill models for fruit and nut trees [Elektronische Daten] [Eike Luedeling, Patrick Brown] Many fruit and nut trees must fulfill a chilling requirement to break their winter dormancy and resume normal growth in spring. Several models exist for quantifying winter chill, and growers and researchers often tacitly assume that the choice of model is not important and estimates of species chilling requirements are valid across growing regions. To test this assumption, Safe Winter Chill (the amount of winter chill that is exceeded in 90% of years) was calculated for 5,078 weather stations around the world, using the Dynamic Model [in Chill Portions (CP)], the Chilling Hours (CH) Model and the Utah Model [Utah Chill Units (UCU)]. Distributions of the ratios between different winter chill metrics were mapped on a global scale. These ratios should be constant if the models were strictly proportional. Ratios between winter chill metrics varied substantially, with the CH/CP ratio ranging between 0 and 34, the UCU/CP ratio between −155 and +20 and the UCU/CH ratio between −10 and +5. The models are thus not proportional, and chilling requirements determined in a given location may not be valid elsewhere. The Utah Model produced negative winter chill totals in many Subtropical regions, where it does not seem to be useful. Mean annual temperature and daily temperature range influenced all winter chill ratios, but explained only between 12 and 27% of the variation. Data on chilling requirements should always be amended with information on the location and experimental conditions of the study in which they were determined, ideally including site-specific conversion factors between winter chill models. This would greatly facilitate the transfer of such information across growing regions, and help prepare growers for the impact of climate change. The Author(s), 2010 Chilling Hours nationallicence Chilling requirement nationallicence Chill Portions nationallicence Dynamic Model nationallicence Utah Model nationallicence Winter chill nationallicence Luedeling Eike Department of Plant Sciences, University of California Davis, One Shields Ave, Mail Stop Two, 95616, Davis, CA, USA aut Brown Patrick Department of Plant Sciences, University of California Davis, One Shields Ave, Mail Stop Two, 95616, Davis, CA, USA aut International Journal of Biometeorology Springer-Verlag 55/3(2011-05-01), 411-421 0020-7128 55:3<411 2011 55 484 https://doi.org/10.1007/s00484-010-0352-y text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s00484-010-0352-y text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Luedeling Eike Department of Plant Sciences, University of California Davis, One Shields Ave, Mail Stop Two, 95616, Davis, CA, USA aut NATIONALLICENCE 700 1- Brown Patrick Department of Plant Sciences, University of California Davis, One Shields Ave, Mail Stop Two, 95616, Davis, CA, USA aut NATIONALLICENCE 773 0- International Journal of Biometeorology Springer-Verlag 55/3(2011-05-01), 411-421 0020-7128 55:3<411 2011 55 484 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer