Climate Change and its Effect on Agricultural Climate Indices of Pistachio Tree in Kerman Province A case study of Rafsanjan Station.

Introduction

The climate of Kerman province is suitable for pistachio cultivation, so the pistachio cultivars of Kerman province are of high quality. Weather conditions play a decisive role in the planting and growth of fruit trees. Climate change will make the agricultural sector vulnerable to changes in temperature and precipitation parameters. Therefore, it is necessary to investigate the future climatic conditions of fruit tree cultivation areas under the influence of climate change. Therefore, it is necessary to investigate the effects of climate change on the climate indicators of pistachio tree agriculture in Kerman province. For this purpose the indicators of temperature, precipitation, and evaporation in the coming decades have been investigated concerning climate change.

Methodology

The trend of changes in temperature, precipitation, and evaporation indices during the observation period of each station was determined using Kendall's statistical test. Based on the CanESM6 climate model, under two scenarios ssp2-4.5 and ssp5-8.5, minimum temperature, maximum temperature and precipitation data have been produced in the coming years. One of the general circulation models (GCM) CanESM5 model was used to predict climate parameters. Downscaling of canESM5 model data was done using SDSM software. The error rate of production data was checked with Base data using validation criteria. First, the process of production data changes in different stages of pistachio phenology was calculated.

Results and Discussion

First, based on the observational data of the period of 1992-2021, the status of the climatic indicators of the pistachio tree and trend of each of them were investigated using the available tests. Based on the temperature of 7.5 degrees Celsius, the five stages of the phenology of the Ohadi cultivar were determined, flowering to full flowering, bone shell hardening, and the beginning of rapid brain growth, the end of brain growth, and the harvest time based on the summary of the day-growth degree. With the downscaling of CanESM5 model output data under SSP5-8.5 and SSP2-4.5 scenarios, daily temperature and precipitation data for Rafsanjan station were simulated for three periods 2075-20100, 2050-2074, and 2025-2049. The results show that in the base period, the temperature indices of the growing season (average daily temperature, average maximum) and average minimum in March and April have a positive significant trend. The flowering (average temperature and average minimum temperature indices) in the future period of 205-2049 under the ssp2-4.5 scenario in the growing season (average daily temperature indices, average maximum, and average minimum temperature) in April have a significant positive trend. The simulation showed that the average daily temperature index in the pistachio growing season under the SSP2-4.5 scenario during 2025-2074 increases compared to the base period (23.5 degrees Celsius) and reaches 24.6 degrees Celsius

Conclusion

the results of the simulation showed that the average daily temperature index in the pistachio growing season in Rafsanjan station under the scenario of SSP2-4.5 were 0.97°C from 2025 to 2074 in the spring season and the months of April and May and the autumn season and the month of October with a positive trend. Under the SSP5-8.5 scenario, the average daily temperature in the two future periods of 2075-2100 and 2050-2074 has a positive increasing trend; and in the final period, the average daily temperature of the growing season will increase by 3.13°C compared to the base period, and the average daily temperature will reach 26.63°C from 23.5°C. The average minimum temperature under the scenario of SSP2-4.5 in the period 2025 - 2049 in April and October has an increasing trend. In addition, the average minimum temperature in March in the period of 2075-2100 has an increasing trend; the average minimum temperature under the above scenario is 0.75°C. The average minimum temperature in March in 2100 - 2075 shows an increase in average temperature under the above scenario. Under the pessimistic scenario SSP5-8.5 during the period 2075 - 2100 and 2050 - 2074, the average minimum temperature has an increasing trend of about 1.76°C. The maximum temperature in the flowering stage under the scenario of SSP2-4.5 in the base period and the future period under 2050 - 2074 and the 2025 - 2049 period will not have a trend. Under the above scenario, the above index has a positive trend in the period of 2075-2100, and on average; it increases by 0.29°C compared to the base period. Under the SSP5-8.5 scenario, the average maximum daily temperature has a positive trend and increases by 1.06°C.The mean daily temperature index in the pistachio-growing season. In Rafsanjan station, the average days with a temperature between 35 and 40 degrees Celsius in the base period are about 39 days. During 2025-2100, under the ssp2-4.5 scenario, the number of days with a temperature of 35 to 40 degrees Celsius shows a decreasing trend. On the other hand, the number of days with temperatures higher than 40 degrees Celsius under the same scenario reveals an increasing trend. From the number of 9 days in the base period, it will reach about 31.5 days between 2025 and 2100. This content also applies to the ssp5-8.5 scenario. And the number of days with temperatures higher than 40 degrees Celsius will reach about 50 days at the end of the future period of 2025-2100, and the trend is significantly positive.