عنوان مقاله [English]
Temperature and water are the most important environmental factors controlling seed germination in plants. In order to investigate the effect of temperature and drought stress on seed germination and quantifying of germination; a factorial experiment was conducted with eight temperature levels including 5, 10, 15, 20, 25, 30, 35 and 40 degrees Celsius and the seven levels of drought stress including 0, 0.5-0.0, -0.2, -0.3, -0.4, -0.5 and -0.6 MPa, respectively. The results showed that the germination was decreased by decreasing osmotic potential at all temperature levels. However, the intensity of this decrease was less in the range of 20 to 30°C. Using two different methods, the base and maximum temperature of dill germination was estimated in the range of 2.3 and 2.9 °C and 43.0 and 47.3 °C, respectively. The optimum temperature for dill germination was 26 °C. The estimated value of base water potential for germination was -0.53 Mpa with the hydrothermal time model. The results also showed that water base potential for dill germination was increased by -0.5 Mpa as temperature increased. Finally, it was found that if the base water potential taking into account variable in response to changing temperature, then the hydrothermal time model can be good enough to quntify dill germination response to temperature and water.
10. Chantre, G. R., Batlla, D., Sabbatini, M. R. & Orioli, G. (2009). Germination parameterization and development of an after-ripening thermal-time model for primary dormancy release of Lithospermum arvense seeds. Annals of Botany, 103 (8), 1291–1301.
11. Dahal, P. & Bradford, K.J. (1994). Hydrothermal time analysis of tomato seed germination at suboptimal temperature and reduced water potential. Seed Science Research, 4(2), 71–80.
12. Ellis, R. H, Covell S., Roberts E.H. & Summerfield R.J. (1986). The influence of temperature on seed germination rate in grain legumes. II. Intraspecific variation in chickpea at constant temperatures. Journal of Experimental Botany, 37(10),1503–1515.
13. Fenner. M. & Thompson K. (2005). The ecology of seeds. Cambridge University Press, Edinburgh House, Cambridge. 250 p.
14. Fernandez, G. & Johnston M. (1995). Seed vigor testing in lentil, bean, and chickpea. Seed Science and Technology, 23(1), 617-627.
15. Finney, D. J. (1971). Probit analysis. Third edition. Cambridge University Press, Cambridge.
16. Grundy, A.C., Phelps, K., Reader, R.J. & Burston, S. (2000). Modelling the germination of Stellaria media using the concept of hydrothermal time. New Phytologist, 148(3), 433–444.
17. Gummerson R. J. (1986). The effect of constant temperatures and osmotic potential on the germination of sugerbeet. Journal of Experimental Botany, 37(7),729–741.
18. Hasandokht, M. R. (2012). Vegetables Production Technology. Selsele Press. Tehran. Iran. (in Farsi)
19. Kebreab, E. & Murdoch, A.J. (1999). Modelling the effects of water stress and temperature on germination rate of Orobanche aegyptiaca seeds. Journal of Experimental Botany ,50 (334), 655–664.
20. Kebreab, E. & Murdoch, A.J.( 2000). The effect of water stress on the temperature germination rate of Orobanche aegyptiaca seeds. Journal of Experimental Botany, 50(2), 655-664.
21. Larsen, S.U., Bailly, C., Côme D. & Corbineau, F. (2004). Use of the hydrothermal time model to analyse interacting effects of water and temperature on germination of three grass species. Seed Science Research, 14 (1), 35-50.
22. Michel, B.E. & Kaufmann, M.R. (1973). The osmotic potential of polyethylene glycol 6000. Plant Physiology 51(5), 914–916.
23. Ni, B.R. & Bradford, K.J. (1992). Quantitative models characterizing seed germination responses to abscisic acid and osmoticum. Plant Physiology, 98(3), 1057–1068.
24. Nozari-nejad, M., Zeinali, E., Soltani, A., Soltani, E. & Kamkar, B. (2013). Quantify wheat germination rate response to temperature and water potential. Journal of Crop production, 6 (4). 117-135. (In Farsi)
25. Rowse, H.R. & Finch-Savage, W. E. (2003). Hydrothermal threshold models can describe the germination response of carrot (Daucus carota) and onion (Allium cepa) seed populations across both sub- and supra-optimal temperatures. New Phytologist, 158(1), 101–108.
26. Steinmaus, S.J., Timonthy, S.P. & Jodie, S.H. (2000). Estimation of base temperature for nine weed species. Journal of Experimental Botany, 51(3), 275– 286.
27. Wang, R., Bai, Y. & Tanino, K. (2005). Germination of winterfat (Eurotia lanata Moq.) seeds at reduced water potentials : testing assumptions of hydrothermal time model. Environmental and Experimental Botany 53(1), 49–63.
28. Wen-Hu, X., Fan, Y., Baskin, C. C., Baskin J.M. & Wang Y. R. (2015). Comparison of the effects of temperature and water potential on seed germination of Fabaceae species from desert and Subalpine grassland. American Journal of Botany 102 (5), 649 – 660.