1- Tarbiat Modares University, Tehran, Iran
2- Master in Physical Geography, Department of Geography, Tarbiat Modares University, Tehran, Iran
3- Assistant Professor, Department of Geography, Tarbiat Modares University, Tehran, Iran
Abstract: (7301 Views)
Climate change has direct and indirect effects on the growth of agricultural products. Wheat is one of the strategic products of the world that is affected by climate change. This research was done in the Khorasan Razavi province in order to study the variability of wheat yield by the change of climatic parmeters including precipitation and temperature. To do this, 11 stations were selected. The climatic parameters included the total monthly precipitation and five parameters of temperature, including; mean annual temperature, mean annuall maximum temperature, mean annual minimum temperature and monthly max-min.
Then the wheat yield in each station was gathered for wheat growth period (phonology) from October to June for 20 years (1984-2003). In each station. The correlation coefficient between the wheat yield and climatic parameters was computed and finally a regression model was provided for the stations to recognize the influential climatic parameters. The climatic parameters influencing wheat yield were established. Daregaz, Ghuchan,
Torbate-Hydariyeh, Torbate-Jam, Kashmar and Gonabad stations had a
regression model, while Sabzevar, Nyshabour, Mashhad, Ferdows and Taybad stations lacked such kind of regression model. Regional model was calculated for the province and compared with the calculated station models.
In the regional model, the parameters of January and February total monthly precipitation, January average temperature, January maximum average temperature and March absolutely minimum temperature were found to be influential in the rain-fed wheat yield. This finding indicates that precipitation paramenters and cold season (winter) temperature are very important in the rain-fed farming wheat yields. Finally prediction scenarious for the regional model and the stations which had models were done and the wheat yield variability considering the climatic parameters’ deviation from normal mean was estimated. In the final process, forecasting scenarios for the zonal and stationbased models were calculated and the variability rate of wheat yield with respect to the climatic parameters deviation from the normal mean was extracted. The results of this study indicated that wheat yield changes from 200 to 534 kg/ha for the zonal model according to the changes in precipitation and temperature.
Received: 2007/11/10 | Accepted: 2008/05/13 | Published: 2010/05/2