The Impact of Climate Variables on Wheat and Corn Yield and Yield Risk in Gazvin Province

The aim of this study is to investigate the impact of climate variables on wheat and corn yields and yield risks in Qazvin province by utilizing the Just-Pope's stochastic production function. For irrigated wheat, mean yield and risk yield functions estimated by the Cobb-Douglas and Linear- quadratic forms, respectively. Results show that aammonia fertilizer, maximum temperature and wind speed during the growth period have significant effects on irrigated wheat yield and increase the yield risk. Also the rain fed wheat yield and yield risk functions were estimated as Cobb-Douglas and Transcendental form, respectively. The results show that the amount of phosphate fertilizer, seed, rainfall during autumn and spring, the wind speed and maximum temperature during the growth period has significant effects on the yield. In this context, maximum temperature and wind speed raise the dry wheat yield risk. Corn yield and risk function were estimated by the linear-quadratic form. The results indicate that maximum temperature and fertilizer consumption have negative impacts on the corn yield. While the maximum temperature and rainfalls reduce the yield risk. So, we can reduce impacts of Unpredictable parameters on yield and yield risk with exactly planning such as risk management.