Modelling the effect of temperature, soil penetration resistance, burial depth and seed weight on pre-emergence growth of weeds

Emergence of the weed species Polygonum persicaria L., Chenopodium album L. and Spergula arvensis L. was studied experimentally, after burial of pre-germinated seeds at different depths in soil with different penetration resistances at a range of constant temperatures in the laboratory. Final percentages of emergence tended to be unaffected by temperature in the range 10-25 degrees C, while they were lower at 5 degrees C. Emergence percentages decreased with increasing soil penetration resistance and increasing burial depth. Rates of emergence increased with increasing temperature, and decreased with increasing soil penetration resistance and increasing burial depth. A physiologically based model was developed to describe the effects of temperature, soil penetration resitance, burial depth and seed weight on preemergence growth of seedlings. The model was used to analyse the experimental data in order to obtain insight into the effects of these factors on seedling emergence. The model provided a good description of the trends observed in the experiment. (C) 1997 Annals of Botany Company the effects of these factors on seedling the experiment.