RESEARCHES REGARDING THE PROGNOSIS OF THE FLOWERING STAGE AND HONEY POTENTIAL YIELD OF SUNFLOWER CROPS

The objective of this research was to develop a prognosis support system that provides users with predictions of the dates of the beginning and end of flowering stage and the honey potential yield of sunflower (Helianthus annuus L.) crops. It is emphasized that this prognosis is a "poor-structured" problem and it can be solved most advantageously by a tool of "decision support system" type. The prognosis method of the flowering stage is based on "thermal time" (TT) measured in "growing degree-days". The model of calculation of the daily biologically active temperature for TT summations uses a "base temperature" of 6.7 ?C and a correction of the average daily temperature. Three TT thresholds are defined: (1) sowing emergence, (2) emergence beginning of flowering, and (3) beginning end of flowering. These TT thresholds and the honey potential yield the prognosis parameters are specific to hybrids, maturity class of hybrids (four classes) and to climatic types of crop years (four types). The (re-) calibration of the prognosis parameters is performed by averaging the sunflower crops historical data that are accumulated during system use (in that way a "self-improving" system is obtained). Four estimation methods of different accuracies are used. The prognosis of meteorological data is performed based on the historical data of the years of the given climatic type estimated by user for the prognosis year. The prognoses of the flowering stage and honey potential yield are based on the calibrated parameters, estimated meteorological data for the prognosis year, and sowing data specified by user.