Investigation of biology of hoary cress (Cardaria draba L) against some edaphic factors

The laboratory studies were conducted at Islamic Azad University, Karaj branch in 2015 to determine the effect of osmotic potential, temperature and salt concentration on hoary cress (Cardaria draba) seed germination. The treatments were seven levels of water potential (0, -0.2, -0.4, -0.6, -0.8, -1 and -1.2 MPa), seven levels of temperature (5, 10, 15, 20, 25, 30 and 35 °C) and seven levels of NaCl concentration (0, 50, 100, 150, 200, 250 and 300 mmol). According to the results in all osmotic levels, germination rate in 10 °C was less than other temperatures. On the other hand, by increasing osmotic potential, more difference between germination rate and percentage was shown in each temperature treatments. Under all of temperatures, increasing resulted in decrease in germination percentage and germination rate but this depression under unmoral temperature (such as 10 °C) was more than others. Germination percentage was zero in 5°C and 35 °C and optimum temperature for the highest germination percentage is predicted as 20.9 °C. In PEG concentration of -0.6 MPa germination percentage was zero. Based on the regression results, salinity stress negatively affected the germination percentage and germination rate. Thus the germination percentage is predicted to reach zero in 285 mmol of NaCl concentration.