Wheat is considered as a staple food of people and as a strategic product. Rainfed wheat is more important than irrigated wheat and temperature is among the most important climactic factors influencing its cultivation. The current study is aimed to detect growing degree days for phenology period of rainfed wheat cultivation for the next 20 years. The studied areas including Fars, Kohgiluyeh and Bouyer Ahmad, and Chahar Mahal and Bakhtiari provinces were determined using digital elevation model of the earth. Meteorological data required including daily temperature and rainfall during a common statistical period of 20 years (1995-2015) were supplied from National Meteorology Organization. Properties of temperature and rainfall discussed in terms of sub hypotheses were studied using statistical indices of central tendency, scatter and possible distributions. Correlation methods, LARS WG and Mann Kendall were used to study the future process and predict climactic elements and indices. Using findings of the current study, database in geographical information system and to prepare maps required and finally hypotheses testing were conducted. During a statistical period of 2015 to 2035 predicted with LARS WG model, southern parts of the studied area and the northern part of Kouhrang station had the least and highest amount of rainfall, respectively. Degree day index of the studied area increased from the north to the south which the highest and lowest amounts were assigned to southern station of the area and northern stations of Borujen, respectively. Most of studied stations had an increasing trend in degree days and only 3 stations including Eghlid, Zarghan and Borujen did not have any increasing and decreasing trend.
Hojatallah Abbasi, Golam Ali Mozaffari, Ahmad Mazidi