عنوان مقاله [English]
نویسندگان [English]چکیده [English]
The effects of environmental factors on germination and longevity of downy brome seeds were examined in laboratory and field experiments. Downy brome could germinate in a broad range of temperatures (15/6, 20/10, 25/15, 30/15, and 35/20ºC). The germinability, however, was different depending on the temperature range and the results showed that the highest germination was occurred in 20/10ºC (91%) under continuous dark regime, while the lowest germination percentage was observed in 35/20ºC (5%) under light/dark conditions. Salinity showed significant adverse effect on germination of this weed, so that the highest germinability was at 0 concentration of NaCl (89%). Increased salinity levels significantly decreased downy brome germination and its germination completely ceased at 320 mM NaCl. This study indicated that increasing pH in the range of 4 to 8 resulted in enhanced germination percentage, while further increase of pH significantly reduced germinability. Another experiment in which seeds were after-ripened at different depths in the field showed that increased burial depths from 0 to 10 cm accelerated seed after ripening and the lowest germination occurred in the seeds which were placed on the soil surface.
Allen, P.S., Meyer, S.E. and Beckstead, J. 1995. Patterns of seed after-ripening in Bromus tectorum L. J. Exp. Bot. 46: 1737-1744.
Anderson, L., Milberg, P., Schütz, W. and Steinmetz, O. 2002. Germination characteristics and emergence time of annual Bromus species of differing weediness in Sweden. Weed Res. 42: 135-147.
Belnap, J., Sherrod, S.K. and Miller, M.E. 2003. Effects of soil amendments on germination and emergence of downy brome (Bromus tectorum) and Hilaria jamesii. Weed Sci. 51: 371-378.
Belnap, J. and Sherrod, S.K. 2008. Soil amendment effects on the exotic annual grass Bromus tectorum L. and facilitation of its growth by the native perennial grass Hilaria jamesii (Torr.) Benth. Plant Ecol. 201: 709-721.
Chauhan, B., Gill, G. and Preston, C. 2006a. Factors affecting seed germination of annual sowthistle (Sonchus oleraceus) in southern Australia. Weed Sci. 54: 854-860.
Chauhan, B., Gill, G. and Preston, C. 2006b. African mustard (Brassica tournefortii) germination in southern Australia. Weed Sci. 54: 891-897.
Chauhan, B. S. and Johnson, D. E. 2008a. Seed germination and seedling emergence of giant sensitiveplant (Mimosa invisa). Weed Sci. 56:244-248.
Chauhan, B. S. and Johnson, D. E. 2008b. Influence of environmental factors on seed germination and seedling emergence of Eclipta (Eclipta prostrata) in a tropical environment. Weed Sci. 56:814-819.
Christensen, M. S., Meyer, E. and Allen, P. 1996. A hydrothermal time model of seed after-ripening in Bromus tectorum L. Seed Sci. Res. 6: 155–163.
Cousens, R.D., Baweja, R., Vaths, J. and Schofield, M. 1993. Comparative biology of cruciferous weeds: a preliminary study. In Proceedings of the 10th Australian and 14th Asian-Pacific Weed Conference. Brisbane, Australia: Weed Society of Queensland, pp 376–380.
Evans, R.A. and Young, J.A. 1987. Seedbed modification with weed control and seeding. In: Frasier, Gary W.; Evans, Raymond A., eds. Seed and seedbed ecology of rangeland plants: proceedings of symposium; 1987 April 21-23; Tucson, AZ. Washington, DC: U.S. Department of Agriculture, Agricultural Research Service: 52-56.
Gasch, C. and Bingham, R. 2006. Variation in seed germination characteristics among populations of Bromus tectorum in the Gunnison Basin. Bios 77: 7-12.
Hartmann, H. T., Kester, D. E., Davies, F. T. and Geneve. R. T. 1997. Plant Propagation: Principles and Practices. 6th ed. Upper Saddle River, NJ: Prentice Hall. Pp. 194–210.
Howell, W. 1998. Germination and establishment of Bromus tectorum L. in relation to cation exchange capacity, seedbed, litter, soil cover and water. M. A. thesis. Prescott College, Arizona.
Kleemann, S. G. L., Chauhan, B. S. and Gill, G. S. 2007. Factors affecting seed germination of Perennial Wall Rocket (Diplotaxis tenuifolia) in Southern Australia. Weed Sci., 55: 481-485.
Meyer, S.E. and Allen, P.S. 1999. Ecological genetics of seed germination regulation in Bromus tectorum. I. Phenotypic variance among and within populations. Oecologia. 120: 27–34.
Miller, M.E. 2000. Effects of resource manipulations and soil characteristics on Bromus tectorum L. and Stipa hymenoides. in calcareous soils of Canyonlands National Park, Utah. Ph.D. dissertation. University of Colorado, Boulder, CO.
Morrison, R.E. 1999. Potassium as a limiting nutrient for germination and production of cheatgrass (Bromus tectorum) in the Canyonlands National Park, Utah. Senior Honors thesis. University of Denver, Denver, CO.
Omami, E.N., Haigh, A.M., Medd, R.W. and Nicol, H.I. 1999. Changes in germinability, dormancy and viability of Amaranthus retroflexus as affected by depth and duration of burial. Weed Res. 39: 345-354.
Pierce, G.L., Warren, S.L., Mikkelsen, R.L. and Linker, H.M. 1999. Effects of soil calcium and pH on seed germination and subsequent growth of large crabgrass (Digitaria sanguinalis). Weed Technol. 13: 421–424.
Rasmuson, D.E., and Anderson, J.E. 2002. Salinity affects development, growth, and photosynthesis in cheatgrass. J. Range Manage. 55: 80-87.
Rollin, P. 1972. Phytochrome control of seed germination.. In K. Mitrakos and W. Shropshire Jr., (eds). Phytochrome. New York: Academic, pp 229–257.
Susko, D.J., Mueller, J.P. and Spears, J.F. 1999. Inﬂuence of environmental factors on germination and emergence of Pueraria lobata. Weed Sci. 47:585–588.
Thompson, L.M. and Troeh, F.R. 1978. Soils and Soil Fertility. 4th ed. New York: McGraw-Hill. pp. 291 and 310–311.
Whitson, T.D. and Koch, D.W. 1998. Control of downy brome (Bromus tectorum) with herbicides and perennial grass competition. Weed Technol. 12: 391-396.
Yenish, J.P., Doll, J.D. and Buhler, D.D. 1992. Effects of tillage on vertical distribution and viability of weed seed in soil. Weed Sci. 40:429–433.
Young, J. 2000. Bromus tectorum L. In: Bossard, Carla C.; Randall, John M.; Hoshovsky, Marc C., eds. Invasive plants of California's wildlands. Berkeley, CA: University of California Press: 76-80.
Young, J. and Clements, C.D. 2000. Cheatgrass control and seeding. Rangelands. 22: 3-7.