Global warming has been affecting some morphological characters of Pistachio trees (Pistacia vera L.)

Climate changes have already affected species distribution shifts in many parts of the world. The data, on which this research is based on, were collected and studied in Kerman province. The meteorology data were on four months (December, January, February and March) from 1991 until 2008 and the phenology data were on six pistachio cultivars that were ranked in three groups: early flowering, mid flowering and late flowering collected during the summers in the following years: 1997, from 2001 until 2005 and 2007. The evaluated factors included leaf area, normal and abnormal leaves. The results showed the mean temperature in March has significantly increased during the monitored period and that fluctuations between the years have increased since 1999, in December, January and February. The abnormality of the leaves in early and late flowering cultivars had the negative correlation with the mean temperature measured in December during the monitored period of time and that the mid flowering cultivars had the positive correlation with the mean temperature measured in February during that same period of time. The changes of leaf area on Ahamadaghaei cultivar were less than in other cultivars but Kallehghoochi and Akbari had the highest range which can probably be used as a good marker for determining effects of temperature changes in winter on the production level.