Prediction of vegetation period duration in spring cereal crops varieties in the conditions of climate changes

On the ground of long-term observations for the wheat, oat and soya specimens on four experimental stations contrasting with respect to climate conditions (N.I. Vavilov Institute of Plant Industry — VIRAll-Russian Scientific Research Institute of Plant Growing) the authors revealed the tendencies towards changes of agroclimatic factors, vegetation period duration in cultivated varieties and also determined the limiting factors for each examined station. The temperature necessities of varieties and their dependence on other climatic factors were determined. The abilities of two methods are considered — a regression analysis and effective temperature method. In the varieties districted early the authors predict the shortening of vegetation period as temperature will rise. The method of sequential differences increases the accuracy of regression analysis and determination of threshold temperatures for varieties. The method of effective temperatures permits to predict the duration of interphase periods in different geographic conditions.