The Effect of Different Planting Dates and Climate Change on Spring Wheat Evapotranspiration and Transpiration in the Qazvin Plain (2100-2021)

It is necessary to predict the effects of climate change on agricultural production in the coming periods in order to ensure the food security of the strategic plant wheat, which plays an essential role in international treaties. Models that generate artificial climate data, such as valid GCM models, are used to investigate the effects of climate change on various systems and are able to model climate parameters for a long period of time using scenarios approved by the Intergovernmental Panel on Climate Change. In the current research, two information sources, LARS-WG and DKRZ, were used to generate climate change data of the Qazvin plain in the period of 2021-2100, then the actual evapotranspiration values of Parsi spring wheat were calculated by the Aquacrop model in different planting dates and the amount of their changes Compared to the base course.

In this research, from the data obtained from the DKRZ web database and the LARS-WG model, to calculate the three variables of minimum temperature, maximum temperature and precipitation, related to Qazvin observation station and five atmospheric general circulation models of the fifth IPCC report (EC-EARTH , GFDL-CM3, HadGEM2-ES, MIROC5, MPI-ESM-MR) were used under two emission scenarios of 4.5 and 8.5 in future rounds (2021-2040, 2041-2060, 2061-2080, 2081-2100). Using the obtained data and applying the Aquacrop model, the amount of actual evaporation-transpiration of spring wheat on 5 different planting dates (15 Bahman, 1 Esfand, 15 Esfand, 1 April and 15 April) was calculated and the amount of their changes compared to the period the base was checked.

Observations show that with cultivation on 15th of Bahman and 1st of March under the climatic conditions obtained from the LARS-WG model in scenario 4/5; In the future period (2040-2021), transpiration will increase compared to its value in the base period, but in the periods (2041-2060, 2061-2080 and 2081-2100) and in the scenario 4.5 and 5.8 from the LARS model - WG average real evapotranspiration will decrease compared to its value in the base period. DKRZ database under scenarios 4.5 and 8.5 predicts a decrease in the average actual evapotranspiration compared to its value in the base period for these two dates in each of the next 4 periods. by planting on March 15, April 1 and April 15, according to the results of the climate conditions of the LARS-WG model and the DKRZ database under scenarios 4/5 and 8/5, in each of the next 4 periods; The average actual evapotranspiration will decrease compared to its value in the base period.

The results show that the average real evapotranspiration will increase compared to its value in the base period, on the two dates of February 15 and March 1 in the period of 2040-2021 in the climate conditions obtained from the LARS-WG model under scenario 4.5.If cultivation is carried out in the rest of the dates, according to the results of the climatic conditions of the LARS-WG model and the DKRZ database under scenarios 4.5 and 5.8, in each of the next 4 periods, the average real evapotranspiration will decrease compared to its value in the base period Will have. The highest evaporation-transpiration in the future periods will occur with cultivation on April 15, under the climate conditions obtained from the LARS-WG model under scenario 4/5 and in the period of 2040-2021. Its value is equal to 289.9 mm (with a standard deviation of 18.33 mm). The lowest evaporation-transpiration in the future periods with cultivation on 15th of Bahman, under the climatic conditions obtained from the DKRZ database under scenario 8.5 and in the period 2081-2100, which is equal to 166.6 mm (with a standard deviation of 82.5 mm).: