1Wroclaw University of Environmental and Life Sciences, Institute of Environmental Protection and Development.
2Wroclaw University of Environmental and Life Sciences, Department of Mathematics.
The study was conducted with the application of the model MoDrY (Model-Dry
periods-Yield) for the estimation of the level of potato yields on the basis of dry
periods occurring during the particular periods between the phenological phases of
the crop plant. A characteristic feature of this model, unlike most existing weatheryield
models, is that the principle of its operation is based only on information on
the occurrence of precipitation. In the study the authors used research material from
the years 1971-1983 and 1985-1996 (25 years) and diurnal sums of atmospheric
precipitation from the same periods. Five interphase periods were adopted for the
analyses: planting-emergence, emergence-lateral shoots, lateral shoots-start of
blooming, start of blooming-haulm drying, haulm drying-harvest. The authors also
used a model of changes in the resources of water available for plants during dry
periods. Six measures were adopted to characterise the error of approximation:
coefficient of correlation, coefficient of determination, mean relative error,
RRMSE, EF and CRM. The coefficient of correlation obtained was at the level of
0.92 and the mean relative error at the level of 9.27%. Validation was performed
by means of the Cross Validation test (CV), version LOO.