SEASONAL CHANGES OF SEED GERMINATION OF Conium maculatum L. - REGRESSION MODELS FOR ESTIMATION

Conium maculatum L. is distributed in all floristic regions in Bulgaria. In the recent years field infestation with this species has increased especially in cereal crops. Thus, the knowledge of the seasonal changes in seed germination is of great importance. The investigations were carried out during the period 2001-2004. The seeds were buried outside at the different depths (5, 10, 20, 30 and 40 cm) and different duration (2, 6, 8, 9, 11, 12, 13, and 18 months). The effects of soil depth, time of burial, air temperature and humidity as well as the hydrothermal coefficient on the seed germination were estimated using the tools of mathematical modeling. The correlation analysis showed burial duration and hydrothermal coefficient as a main factors of influence. The soil depth impact increases with increase of the burial duration and is most significant if the seeds have been buried during 11-12 months. Different models were developed to describe the single or combined impact of the observed factors. A fractional-polynomial relationship was obtained between the dynamic of the seed germination and burial duration. The fitted regression models showed that the maximum seed germination appears in the 12th month.