Investigation of Climate Change Occurrence and its Impact on Rainfall Wheat Phenology in West and Northwest of Iran

Introduction:

Climate change will affect all sectors of the economy to some extent, but the agricultural sector may be the most sensitive and most vulnerable part because agricultural products are highly dependent on climate resources, And according to scientific evidence, future climate change, especially the combined effects of elevated temperatures and elevated atmospheric CO2 concentrations, will have a significant impact on crops (droughts, floods, frosts) on crops( Chiottioud ,1995). The general effects of climate change on crop development vary depending on the plant and study area (Rawlins, 1991), and commenting on the response of different species to climate change requires case studies.

area of study The study area includes west and northwest of the country Uncovering Climate Change in Past Times Climatic data of maximum temperature, minimum temperature, 30-year historical rainfall (1988-2008) were obtained from 23 stations in the west and northwest of the country And Using two nonparametric tests Mann-Kendall and Estimator slop sen, the trend of precipitation and temperature changes was investigated in order to detect climate change phenomenon in the region. Generating climate scenarios in future periods To assess future climate change in the west and northwest of the country, the CCSM4 general circulation model under RCP4.5 scenario is one of a number of new RCP emission scenarios that the Climate Change Intervention Board will develop in its Fifth Assessment Report (AR5) as representative of the linesVarious concentrations of greenhouse gases have been used Predictive model of wheat phenology and yield unctional and phenological data for three years (90-93) with 40 climatic parameters (Table 2) from seven stations (Zanjan, Arak, Sararood, Maragheh, Ghamloo, Ardabil and Orumieh) containing performance and phenology data Was prepared Then, using these data, performance and phenology in the baseline and future period were predicted through simple linear regression, multiple regression. The results consisted of 20 regression models The best model was selected based on R-squard index using RMSE.

February, March, September, and the year are at 99 percent confidence levels, while January, June, July and August are at 95 percent confidence levels. As well as total rainfall, both the upward and downward trends have a significant and decreasing trend at 95% confidence level only in January and March. Changes in temperature and rainfall in the coming period The results of climate change assessment at each of the stations in the future climate show that the mean maximum temperature in the future climate has increased at 14 stations compared to the previous climate and decreased at the other stations. The mean minimum temperature in the future climate has increased in all the stations except for Ghamloo and Sanandaj stations compared to the previous climate. Average temperature also increased at all stations except Ahar, Zarineh, Sarab and Ghomloo stations in all stations compared to past climates Average mean precipitation in all stations excluding sarpolzahab station in future climates It increases with the past climate Impact of Climate Change on Phenology nder the climate change, the length of the flowering stage of the wheat in the future climate will be shorter than in the previous climate, so that the flowering stage length in all the studied stations with the exception of Zarrineh station in the next period (2039-2018 ) Is shorter than the average long-term flowering stage of wheat. he mean flowering stage duration in the basal climate is 136 days, whereas the mean flowering stage duration in the future climate is 118 days, ie the average flowering stage duration in the future climate is 18 days short. Increasingly, the shortening of the flowering stage in future climates is due to the increase in average temperature in May and April and average maximum temperature in December. Impact of Climate Change on PerformanceUnder climate change, wheat grain yields will increase in future climates than in the past, so that at all stations with the exception of Mahabad station, wheat grain yield is higher than the long-term average in the past. verage wheat yield in the past climate was 1863.3 kg / ha but in the future climate it would be 2529.9 kg / ha. Wheat yields are up 35 percent due to the favorable future climate in the region.

tudies show that precipitation in the west and northwest region of the country during the past period has been decreasing and the temperature is increasing in most months of the year. And in the coming period the temperature in all months of the year until the end of 2039 shows an increase of 2.5 to 3.5 ° C. The flowering period is also 136 days for the previous period but 118 days for the next period shortening of flowering stage of wheat plant is due to increase in average temperature in May and April and average maximum temperature in December as well as increase in precipitation in December and February. Comparison of wheat grain yields of the current and past periods showed that wheat grain yields will increase by 35% in the future, due to the increase in average March and April temperatures and average January and March minimum temperatures. It also saw an increase in the average precipitation of February and March in the next period compared to the previous period.