Temporal Variations of Degree-Day Required for Soybean Based on Climate Changes in the (Future) Coming Decades Case Study: Gorgan City

Nowadays, global warming and its impact on various fields such as agriculture, economics, energy, and politics are interested to researchers. Therefore, it is interesting to investigate the effect of global warming on agriculture and safeness of food for the residents. Soy bean is one of those products which seem to be important and strategic for various areas, especially Gorgan. In this study data were obtained on a daily, monthly and annual basis considering minimum and maximum degrees for long-term observation since 1961 to 1990 from the Meteorological Department. For this study, to evaluate various effects of climate change over two periods of 2034-2049 and 2065-2079 on the scale of degree-day, the model HasCM3 was used. But the outputs of this model were evaluated by using Lard-WG on daily station scale. Moreover, to investigate the role of scenarios, scenarios of A1, A1B and B2 were used. As for the heat output for various scenarios, the most pessimistic result which is equivalent to the maximum degree is the A2 scenario with the temperature increase of 0.64 ° C for the period 2035-2049 and 0.60 ° C for the period 2065 to 2079. However, on the basis of the degree increase, the trend of degree-day for most scenarios and simulated years increased, although the values for the late summer and early autumn ​​coincided with the summer planting showed a decrease in degree-day trend. But based on long term statistics from 2011 to 2100, the trend of degree-day showed an increase for spring planting and a decrease for summer crop. So it is recommended that in the coming decades due to climate change, early planting of this crop in the summer should be implemented. This is because of the fact soybean can provide its appropriate degree-day value in a brief period.[1].