Spring wheat crop yield determination in the half-cycle of solar activity

The research results on modeling and theoretical explanation of the changes in spring wheat crop yield, depending on the vegetation period in the half-cycle of solar activity, which falls within 2000-2012 years, are considered in the article. The conducted research gives the grounds to believe that inclusion of time structure pairing in solar activity and spring wheat crop yield, and also properties of their cyclicity that are expressed in terms of regression analysis allows to explain more than 95% of crop yield change in the time range of 2000-2012 years.