Effects of salinity and drought stress on germination and seedling growth of Avena fatua L. and Phalaris minor L. Arezo Dinari 1*, Fariba Meighani 2 and Mozhgan Farzami Sepehr 1

Avena fatua and Phalaris minor are narrow-leaved weeds that pose problems for many crops. In order to study the effects of sodium chloride (NaCl) and polyethylene glycol (PEG) on germination and initial seedling growth of Avena fatua and Phalaris minor, an experiment was conducted based on a completely randomized design with 4 replications under laboratory conditions during 2011-2012. Eight levels of NaCl: 0 (control), 50, 100, 150, 200, 250, 300, and 350 mM, and 8 PEG concentrations: 0 (control), 15.6, 100.7, 151.4, 190.5, 223.6, 279.3, and 326.2 g/L were used. The findings suggested that in both weed plantlets, increase in NaCl and PEG concentrations resulted in reduced seed germination, and seedling shoot and rootlet length, as compared with the control with no drought stress. In the treatments with high concentrations of NaCl and PEG, seed germination in both weeds approached zero which suggests their sensitivity to salt and drought stress. Overall, it seems that Avena fatua was more tolerant to salt and drought stress in comparison with Phalaris minor.