The Effects of Climate Change on Yield and Phenological Stages of Potato Plant (Case Study: South of Kerman Province)

 Food security is one of the most important concerns of human society. Given the importance of climate for the agricultural sector, achieving long-term climate forecasts in this area is essential. The advent of global climate (GCM) and regional models (RCM) has made it possible for researchers to study the impact of climate on agricultural products. Predicted climate change, especially the increase in atmospheric carbon dioxide and temperature, as well as changes in the amount and patterns of rainfall, will have severe effects on agricultural production and food security, especially in arid and semi-arid regions. Therefore, any change in the world climate, directly affects the production of agricultural products in different parts of the world and, consequently, the issue of food security in the world. This study was conducted to investigate the effects of climate change on yield and length of phenological stages of potato plant in tropical and subtropical regions of Kerman province.

 The study area in this research includes stations with a statistical period of 17 years (1989 to 2005), including Jiroft, Kahnooj, and Manojan. In this study, maximum and minimum temperature data, precipitation, average relative humidity, average wind speed, and sunny hours on a daily time scale were used for the exponential microscale. From the output of the CanESM2 general circulation model was used under the three scenarios rcp2.6, rcp4.5, and rcp8.5. The SDSM microscale model was used to exponentially scale the output of the general circulation model. In order to prepare field data for calibration and to determine the validity of the WOFOST model in potential conditions, data from research projects of Jiroft Agricultural Research Center during 2010-2011 were collected and used as a basic course. This information includes planting date, phenological stages from planting to emergence, emergence to flowering, and emergence to physiological maturity of the potato plant in the study areas.

 The results of WOFOST model validation for phenological stages and potato yield provided acceptable estimates for both variables. The ability of the SDSM model to simulate meteorological parameters was confirmed, however, the model showed less accuracy in simulating precipitation. The simulated maximum and minimum temperatures for the next period (2011-2100) under RCP scenarios increased compared to the observation period in all three RCP scenarios. Precipitation has also will change in future periods in all three scenarios and show a declining trend. Combining the results of the CanESM2 climate model under RCP scenarios in three climate periods 2011-2041, 2041-2070 and 2071-2100 with the WOFOST growth simulation model showed that the length of different phenological stages and potato tuber yield under potential conditions will be reduced in the study areas. The stage of germination to the physiological maturation of the tubers, due to its longer duration, the greatest reduction in the length of the period occurred in this stage. The results of potato tuber yield simulation showed a decrease in yield in the study areas. According to the results, the highest reduction in performance was observed in the third period (2071-2100). The percentage of glandular function reduction was observed on average between 2 and 4.3%. In general, the results showed an increase in the average minimum and maximum temperatures of 0.37 to 0.9 degrees Celsius over the next three periods. The length of the phenological stages of the potato plant from emergence to physiological maturity has decreased in parallel with the increase in the mean minimum and maximum temperatures. The reduction in the length of the germination stage is between 0.2 to 1.9 days, the flowering stage is between 0.5 to 1.7 days, and the maturation stage to maturity is between 1.4 to 3.5 days. The greatest reduction during the phenological stages is related to the emergence stage to maturity of 3.5 days.

  In general, the results of this study indicate an increase in the negative effects of climate change on the potato plant in three stations of Jiroft, Kahnooj, and Manojan. As the temperature rises and the rainfall decreases, and naturally, the length of the growing season and the yield of potatoes decrease, the amount of damage in future climates will increase. Generally, for one degree Celsius increase in average annual temperature, tuber yield will decrease by 4.99%.