investigating the impact of climate change on the phenology stages of autumn wheat in mazandaran province, iran

Anthropogenic climate change can affect crop phenological stages. this study aims to investigate the impacts of climate change on climatic parameters and wheat phenology stages in mazandaran province in the north of iran. for this purpose, the canesm5 model in three shared socioeconomic pathway scenarios (ssp126, ssp245, and ssp585) was analyzed in three periods (2025-2049, 2050-2074, and 2075-2100). in order to evaluate the downscaling model, some indicators such as root mean square error, mean bias error, correlation coefficient, and nash-sutcliffe were employed. also, to investigate the effect of climate change on wheat phenological stages, the growing degree days of each phenological stage were used. the findings indicated a temperature increase of 1.5 to 5 °c across minimum, maximum, and mean temperatures. growing degree days variation results showed that the highest annual growing degree days is in the third period (i.e., 2075-2100), with an increase of 68.5% compared to the base period (1986-2020) under scenario ssp585. based on the findings, it is projected that climate change will lead to a decrease in growth period length of autumn wheat. this reduction could range from 40 to 70 days, affecting all phenological stages of autumn wheat except for the waxy ripe and maturity stages. as a result of the shortened growth period length, the waxy ripe and maturity stages will occur in colder weather conditions, thereby prolonging the final phenological stages of autumn wheat. considering the uncertainty of climate models, examining several general circulation models can help to express more accurate opinion on growth period length of wheat in the future.