Document Type : Research Article
Authors
Kharazmi University of Tehran
Abstract
Introduction: The effect of climate factors plays an important role on agricultural products. In this case, there is not enough knowledge about the role of climatic elements in agricultural planning, therefore, there wouldnot be much achievements because it is proved that in most cases, the low yield of agricultural products is the result of not keeping and being unable to create a balanced climate. Temperature stresses are one of the most important factors in plant growth. In most plants, when the plant is exposed to extreme temperatures, physiological changes may prevent optimal plant growth. Therefore, plants need a specific temperature range for optimum growth and stepping outside of range is considered as a stress. Strawberries are generally herbaceous plants that are one of the most sedentary, dense, isolated petals without stems, more or less articulate with lower leaves and narrow stolon that are sensitive to temperature stresses. This temperature fluctuation causes major annual damage. Therefore, this study was carried out to investigate the extreme temperatures in the strawberry growing area in Kurdistan province (Sanandaj-Marivan-Kamyaran) and the effect of these stressful temperatures on strawberry yield, as well as future temperature prediction and future effects were investigated.
Methods and Approaches: In this study, the average daily temperature, maximum daily temperature and minimum daily temperature duringthe years 1381-1395 were obtained from Iran Meteorological Organization and the occurrence date of the last temperature (spring minimum temperature) for strawberry (5 ° C), which is actually the date of the beginning of the strawberry growth period. Also, the date of occurrence of the first stress temperature (maximum summer temperature) for strawberry (35 ° C) and the length of growth period of strawberry were estimated in the studied years. Data from the production and yield of strawberries were collected from the Jihad Agriculture Organization in Kurdistan province during this 15-year period. In order to study the effect of extreme temperature and the occurrence date of this temperature on the yield of strawberry, using Spearman correlation coefficient (SPSS), correlation between severe temperature and strawberry yield was calculated. Finally, in order to investigate the effect of climate change on the maximum and minimum temperature data in the future, using the SDSM model under the rcp26 scenario, CMIP5 climate scenarios were produced in the 2050-2020 and 2099-2099 periods.
Results and Discussion: The results indicated that the date of the extreme temperature did not change much and the latter extreme temperatures have tended to be more prevalent in the spring. The onset of the first extreme temperatures is also early in the summer of late July and we see an almost short (four-month) growth season for the growth of outdoor strawberries. Minimum temperature has the greatest effect on the yield of strawberries in April and the maximum temperature has the greatest impact in July. This issue is justified by the unfavorable temperature for growing strawberries and low yields in these months. The highest correlation between monthly average temperature and monthly yield of strawberries is in May and June. The simulated future data shows that in the months of the growing season (spring and summer), the temperature increases one to two degrees and the early minimum temperature and the maximum summer temperature will be lower than the base period.
Conclusion: The results of the correlation calculation between the date of the last event and the first critical temperature indicate a weak correlation, and it can be concluded that the occurrence of the first and the last extreme temperatures does not affect each other. The results of the study of the effect of the monthly average temperature on the monthly yield of strawberries in May and June showed that the average daily temperature of 12 to 25 °C, especially 17 to 20 °C, is higher on strawberries. Temperature higher and lower than this range (12 to 25 °C) reduces or stops growth. According to the data produced, the final temperature (minimum spring temperature) occurs a little earlier, and strawberries begin to grow in early March, but this could be risky and a sudden cold time causes a lot of damage. The maximum summer temperatures are also higher. This is true especially in June, when strawberries have the highest yield, it is not good and it stops plant growth. The strawberry growth season is expected to begin in March and end in June. Therefore, measures should be taken to prevent possible damage by raising awareness of the subject.
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