عنوان مقاله [English]
In order to study the effects of PGPR application methods on biological yield and Chl a+b content of Yarrow (Achilea millefolium L.) under drought stress conditions an experiment was performed at Islamic Azad University, Yadegar-e-Imam Khomeini (RAH) Shahre-Rey Branch. This experiment was carried out as a split plot based on randomized completely randomized block design with three replications. Experimental factors were included irrigation regimes as the main plot in three levels (50, 90 and 130 mm evaporation from a class pan) and PGPR application methods in four levels (Non application, root inoculation, application in irrigation water, and root inoculation+ application in irrigation) as the subplot. The results indicated that, simple effect of irrigation and PGPRS were significant on experimented traits but the interaction effects were meaningful only on biological yield content at 5% level of Probability. In this case, drought stress decrease both biological yield and Chl a+b content of yarrow. The treated plants with PGPRS had more evaluated traits compare to control. The results revealed that root inoculation + PGPR application in irrigation were more effective than the other application methods for decreasing harmless effects of drought. So the highest biological yield content (7142 kg/hec) belonged to the normal irrigation condition (50 mm irrigation regime) and 4th level of PGPR application method (root inoculation+ application in irrigation). and the highest Chl a+b content (3.7767 Mg per gram of fresh weight) belonged to the normal irrigation condition (50 mm irrigation regime) and 4th level of PGPR application method (root inoculation+ application in irrigation).