واکاوی روند متوسط دمای زیرحوضه های قائنات در مراحل مختلف فنولوژی محصول زرشک

Introduction

Climate change is a global issue that has attracted the attention of many researchers in recent years. Climate change causes changes in temperature and precipitation patterns, and these changes affect plant performance. As far as can be said, the agricultural sector is the most affected by the climate and its changes. Climate changes in the long term lead to changes in the pattern of cultivation and distribution of plants. Knowledge of how agricultural and horticultural plants react to global warming and climate change and predicting its effects on the performance and area of cultivation of agricultural and horticultural plants in the future requires knowledge of the effects of climate change on plant phenology. The effects of climate change on agricultural production have attracted the attention of many researchers. Severe droughts and temperature increase affect the development of plants and this can be one of the reasons for the reduction of agricultural products (Ridsma, 2007 and Saklaskin, 2008).



Materials and methods

To conduct this research, the monthly average temperature data of Ghaen, Gonabad, Ferdous, Birjand, Khorbirjand, Kashmar and Torbat Heydarieh stations during the period of 1989-2021 have been used. In order to check the trends of the studied data, first, the normality of the data was measured using the Anderson-Darling test. Then, parametric t test was used for normal data and non-parametric Mann-Kendall test was used for non-normal data. Next, temperature zoning maps of the basin were drawn using the topographic layer in Arc Gis software.



Results and discussion

The average temperature trend of the studied stations showed that in April, only Kashmer station had no trend and other stations had an increasing trend. In May, Birjand and Khorbirjand were without, and other stations showed an increasing trend. In June Khorbirjand and in July Khorbirjand and Birjand were without trend. Other stations have shown an increasing trend. In August, Birjand and Khorbirjand had no trends. In September, only Ghaen station had an increasing trend, and other stations had no trend. In October, Ferdous, Birjand, Ghaen and Torbat Heydarieh stations have shown an increasing trend. Other stations have also been without trends. In February, Birjand and Khorbirjand stations had no trend and other stations had an increasing trend. According to the altitude factor, isothermal maps showed that in April, the south to southwest and the northern half of the basin from the northwest to the east of the basin have the appropriate temperature, height and slope for barberry germination. In May, areas of the basin in the form of a strip from the northwest to the east of the basin and the southern half of the basin have a temperature of 19 to 23 degrees Celsius and are suitable for barberry flowering. During the months of May to October, temperatures between 19 and 23 degrees Celsius have been observed in areas of the Qaenat basin. In identifying suitable areas for barberry growth, in addition to temperature, the factor of height and slope should also be considered. Because there are areas that have a temperature of 19 to 23 degrees Celsius, but they are in low altitude areas or areas with high slopes and are not suitable for barberry cultivation. Examining the topography, slope and isothermal maps of the basin shows that in Khordad month, the areas from the west to the southeast of the basin, which are suitable for barberry growth in terms of height and slope, also have favorable conditions for barberry in terms of temperature. In the months of July and August, the size of suitable areas for barberry growth, which was observed in June, has decreased. In September, areas in the center and south of the basin have a temperature of 19 to 23 degrees, but in terms of altitude, the areas in the center of the basin have more suitable conditions for barberry growth than the southern areas of the basin. In October, areas in the north, south, and northwest of the basin have a temperature of 19 to 23 degrees Celsius, but the northern areas of the basin do not have suitable conditions for growing barberry in terms of altitude, and the areas to the south of the basin are suitable for growing barberry. In the months of Shahrivar and Mehr, the most suitable area is the busiest area of the basin. From the middle of November, barberry growth ends. In the months of November, December, January, February and March, the temperature of the entire area of the Qaenat basin is below 12 degrees Celsius and the period of winter stagnation is barren.



Conclusion

In this research, the trend of average temperature changes in the Qaenat basin was investigated and its effects on barberry yield were investigated. Examining the temperature trend in the studied basin showed that the temperature is increasing and in the months of April to August and also in the month of February, the temperature inside the basin has been increasing. Examining the isothermal maps of the basin indicates that the areas of the basin that have a height of over 1000 meters and are stretched from the west to the southeast of the basin have suitable temperature conditions for germination, flowering and fruiting of barberry. Correspondence of the time series of May temperature with the temperature range of 19 to 23 °C showed that since 1999, when the average temperature of May in the basin was between 19 and 23 °C, the production and yield of barberry has also increased. Considering that the temperature in the study basin has an increasing trend and the growing period of barberry has different temperature conditions in each stage, the increase in the temperature of the basin can lead to the displacement of the months of the growing period of barberry. Barberry is a product that grows better in cold and mountainous areas, if the temperature increases in the study area, it affects the yield of the product and causes a quantitative and qualitative decrease of this product.