Introduction

Weather changes affect crops in different ways and indirectly change the prevalence and severity of pests and diseases; Therefore, it is necessary to adapt the agricultural system to the current scenario of climate change to provide more flexibility and ability to respond to farmers. Among these adaptations the prediction of the final production of the product, the identification of the most important effective factors and potential risk times. Razavi Khorasan, as one of the hubs of grape production in Iran, has a special importance in viticulture and the production of processed grape products. Considering the global climate changes and the increase in temperature and rainfall fluctuations, investigating the role of climate variables on the yield of grapes in this region is of great importance. Accurate knowledge of these effects provides the possibility of more accurate prediction of crop performance, optimal planning for farm management and taking appropriate measures to deal with the adverse effects of climate change.

Data and research method

The study area of this thesis is Khorasan Razavi province located in the northeast of Iran. Khorasan Razavi province is located between 56°19' to 61°16' east longitude and 33°52' to 37°42' north latitude, from the north to the country of Turkmenistan, from the east to Afghanistan, from the west and north The west is limited to the provinces of North Khorasan, Semnan and Yazd, and the south and southwest are limited to the provinces of South Khorasan and Yazd.

The data used are from three synoptic stations of Qochan, Sabzevar and Kashmar for the period 1990 to 2014 for temperature and precipitation variables.

Coupled models of the Sixth Phase Intercomparison Project (CMIP6)

The output of the sixth phase or CMIP6 models under common socio-economic scenarios (SSPs) along with the representative scenarios of greenhouse gas concentration on the analysis of feedbacks between climate changes and socio-economic factors such as global population growth, economic development and technological advances in are available In this research, MPI-ESM-HR model scaled with CMhyd model is used. Two intermediate (SSP2-4.5) and pessimistic (SSP5-8.5) scenarios have been used to examine limit profiles for three periods: the near future (2026-2050), the middle future (2025-2075), and the far future (2076-2100).

Results and discussion

Examining the available data from 1377 to 1399 shows that the area under grape cultivation was 4609 hectares in Qochan, 2210 hectares in Sabzevar and 8412 hectares in Kashmar. These statistics show that Kashmar city has the largest cultivated area with a significant difference compared to the other two cities. This issue could be due to more suitable climatic conditions or more supportive policies in this region. which indicates higher efficiency and better management of vineyards in this region. In general, according to the presented statistics, it can be concluded that Kashmar city has the highest cultivated area and crop yield, which indicates the high potential of this city for grape production. Quchan has a good yield despite the smaller cultivated area compared to Kashmir, which may be due to modern agricultural methods or better orchard management.

The analysis of the trend of cultivated area and yield of grapes in Qochan, Sabzevar and Kashmar cities of Khorasan Razavi province based on the statistical data of the Ministry of Agricultural Jihad during the period 1377 to 1399 shows significant changes that can help to better understand the agricultural situation in these areas. The results of the corrected Mann-Kendall test for the area under grape cultivation in these three cities are as follows. In Qochan, z-score equal to -1.33 and P-Value equal to 0.1819 were obtained, which indicates the non-significance of the trend at the 5% level. The value of the trend slope test has also shown a decrease in cultivated area with a slope of -32.66. In Sabzevar, the z-score is -0.21 and P-Value is 0.8261, which clearly indicates no significant change in the cultivated area. The value of the trend slope test is 3.31 hectares per year. Also, in Kashmar, the z-score is equal to 1.003 and P-Value is calculated equal to 0.3155, which means no significant change in the cultivated area with a slope of 10.64 hectares per year.

The results show that in the historical period, Qochan experienced 121.56 days, Sabzevar 66.84 days and Kashmar 24.04 days of frost. These statistics highlight the importance of frost as a key factor in reducing grape yield in these regions. Based on the results of the future forecasts, the frost days are decreasing with a steep slope under both scenarios. Specifically, by the end of this century, the number of freezing days for Kashmar is projected to reach 2.3 days under the SSP2-4.5 scenario and almost 0.36 days under the pessimistic SSP5-8.5 scenario.

conclusion

A comprehensive analysis of climate change and its effect on grape yield in Qochan, Sabzevar and Kashmar cities of Khorasan Razavi province shows a worrying trend that requires serious attention and preventive measures. Examining the changes in grape yield in the main growing areas of this crop in Khorasan Razavi province has shown that frost and severe cold in 2016 and 2018 were the main reason for the decrease in grape yield in Qochan, Kashmar and Sabzevar regions. In confirmation of the findings of this research, Lorenzo et al. (2012) also investigated the important role of temperature in the grape production cycle and showed that this climatic variable affects the quantity and especially the quality of grapes. Another study by van Leeuwen et al. (2019) in France showed that climate change can cause changes in the timing of grape phenological stages, which affects the quality and quantity of the crop. these findings can be compared with several similar international researches. In a study conducted by Ferreira et al. (2020) in Portugal, the impact of climate change on grape production in the Douro region was investigated. The results showed that an increase in temperature and a decrease in rainfall can lead to a 30-40% decrease in grape yield by 2050, which is consistent with the findings of the present study in Khorasan Razavi.