Univrsity of Tehran Press Iranian Journal of Field Crop Science 2008-4811 50 3 2019 10 23 The ecology of Canada thistle (Cirsium arvense L.) seed germination The ecology of Canada thistle (Cirsium arvense L.) seed germination 17 30 73297 10.22059/ijfcs.2018.235751.654339 FA Ehsan Dadkhahi MSc Graduate, University of Tehran Hassan Alizadeh University of Tehran 0000-0002-5685-6567 Mostafa Oveisi University of Tehran 0000-0003-0742-5485 Arash Mamedi Journal Article 2017 06 25 Canada thistle (Cirsium arvense) is a noxious weed and one of the most problematic weeds in field crops, orchards, vegetables, pastures and grasslands in Iran. Determining the ecological factors of this grass weed will contribute to development of its control programs. In order to study germination characteristics to water and salinity stress conditions at different temperatures, an experiment was conducted. Temperatures regimes included 5, 10, 15, 20, 25, 30 and 35°C. For each temperature the treatment, for salinity and water stress was 4 potentials (zero, -4, -8, and -12 bar) of NaCl and 4 potentials (zero, -4, -8, and -12 bar) of PEG. Results showed that increasing salinity stress decreased significantly germination rate and percentage. Tb germination was increased from 11°C to 22°C in -12 salinity potential and Tc decreased from 42°C to 33°C. Result showed that seed germination under drought was more sensitive, so that germination percentage at -8 bar was zero. Obtained germination data for high salinity and drought clearly showed that the permissive temperature range for germination was limited. Canada thistle (Cirsium arvense) is a noxious weed and one of the most problematic weeds in field crops, orchards, vegetables, pastures and grasslands in Iran. Determining the ecological factors of this grass weed will contribute to development of its control programs. In order to study germination characteristics to water and salinity stress conditions at different temperatures, an experiment was conducted. Temperatures regimes included 5, 10, 15, 20, 25, 30 and 35°C. For each temperature the treatment, for salinity and water stress was 4 potentials (zero, -4, -8, and -12 bar) of NaCl and 4 potentials (zero, -4, -8, and -12 bar) of PEG. Results showed that increasing salinity stress decreased significantly germination rate and percentage. Tb germination was increased from 11°C to 22°C in -12 salinity potential and Tc decreased from 42°C to 33°C. Result showed that seed germination under drought was more sensitive, so that germination percentage at -8 bar was zero. Obtained germination data for high salinity and drought clearly showed that the permissive temperature range for germination was limited.

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