Modelling the effect of light intensity and duration of exposure on seed germination of Phalaris minor and Poa annua

Abstract

Ohadi S, Rahimian Mashhadi H, Tavakkol‐Afshari R & Beheshtian Mesgaran M (2010). Modelling the effect of light intensity and duration of exposure on seed germination of Phalaris minor and Poa annua. Weed Research50, 209–217.SummaryPhotocontrol of weeds requires a better understanding of the effect of light on seed germination. Therefore, the effect of light intensity and exposure duration was tested on seed germination of two winter annual weeds, Phalaris minor and Poa annua. Photo‐sensitised seeds of both species were subjected to four light intensities, including 130, 250, 500 and 1000 μmol m−2 s−1, each at six exposure durations of 0.1, 1, 10, 100, 1000 and 10 000 s. Light stimulated the germination of both weeds. A modelling approach was used to describe the relationship between light intensity and exposure duration with the germination of weed seeds. A combination of logistic and Gaussian models provided good fits to P. minor percentage germination data, whereas in the case of P. annua, the incorporation of logistic and quadratic models better described the relationships. According to the model, increasing light intensity from 0 (full darkness) to 1000 μmol m−2 s−1 increased the germination of P. minor and P. annua from 28% to 57% and from 0% to 35% respectively. The seed germination of both weed species increased with exposure duration, but declined at duration periods longer than 100 s in P. minor or 1000 s in P. annua. The model predicted a trade‐off between light intensity and light duration for both weeds. That is, a high light intensity irradiated for a short time exposure may result in the same percentage germination as one with a low light intensity, but at longer exposure duration.