ASSESSMENT OF FUTURE WINTER CHILL IN EGYPT.

Climate change has affected the rates of chilling and heat accumulation, which are vital for flowering and production, in temperate fruit trees. The aim of this study is to investigate current and projected future changes in winter chill in Egypt. The study was carried out on 20 locations in Egypt distributed into Lower, Middle, and Upper Egypt, in addition to outside valley region. The winter chill units for the months from October to February depending on the 7.2 and 10 °C models has been calculated for each season and the accumulation units each 10 years. The future climate data has been obtained from downscaling ECHAM6 GCM of RCP 4.5 scenario from 2010 up to 2090. Results of this study found that, the winter chill units tend to decrease in the future at all Egyptian locations, and there are an extreme decrement in temperature during (2051-2060) and (2061-2070) periods will effect on Aswan and Gharbia locations respectively and led to increasing the winter chill units during these periods, on other side, there is an extreme increment in temperature at Minya location during (2061-2070) period will led to decrease the winter chill units during this period in it. The highest winter chill units have been found in Matruh location while the lowest one was Kafr El-Sheikh location among the studied locations. The fruit trees will likely need to develop agricultural adaptation measures (e.g. low-chill varieties and dormancy-breaking chemicals) to cope with these projected changes.