Effect of Drought stress and use of Vesicular Arbuscular Mycorrhizal (VAM) fungi (Glomus mosseae and Glomus intraradices) on Grain yield, Biological yield and Harvest Index on safflower(Carthamustinctorius L.)

Safflower (Carthamus tinctorius L.) has an important role in supplying the needed oilseeds of Iran as a native plant and due to its specific characteristics such as, medicinal and nutritional use of its flowers, high quality vegetable oil due to having more than 90% unsaturated fatty acids; particularly linoleic and oleic acid, a nutritional supplement for livestock and relatively high resistance to environmental stresses such as salinity, drought and cold conditions (Ashkani and Pakniyat, 2003). Vesicular Arbuscular Mycorrhizal (VAM) fungi is one of the biological agents which includes a major part of soil organisms; Mycorrhizal fungi modulates the adverse effects of drought stress in plants (Troehza , 2003). An experiment was carried out during the growing season of 2012 at Agricultural Research Station of Islamic Azad University Varamin–Pishva Branch to evaluate the effect of mycorrhizal and drought stress on safflower yield. A split plot based on randomized complete block design was used with three replications. (complete irrigation, irrigation withholding at 50 percent flowering stage, irrigation withholding at 100 percent flowering and irrigation withholding at grain filling stage) and using mycorrhizal as the sub-factor at three levels (Not using mycorrhizal, using mycorrhizal Glomus mosseae species, using mycorrhizal Glomus intraradices species).Mycorrhizal fungi changes plant water relations and also enhance the absorption of nutrients by increasing the root surface or the effective length of the root. Experiments on the traits such as grain yield, biological yield and harvest index, showed significant differences between the effects of drought stress treatments and mycorrhizal fungi treatment at 1% (Grain yield) and 5% (harvest index and biological yield).The highest grain yield, as the most important attribute of the study, was observed in mycorrhizal fungi treatment of Glomus intraradices species and mycorrhizal fungi of Glomus mosseae species. The results of this experiment showed that the most sensitive stage of irrigation was in 50 % of flowering stage. Because, withholding the irrigation in flowering stages is more critical than the grain filling stage in safflower (Omidi, 2009). Also, by examining the effects of Mycorrhizal fungi in this experiment determined that the effects of mycorrhizal fungi as biofertilizers could increase yield and reduce the negative effects of stress and maintain the plant under drought stress.

Keywords:

Safflower , Mycorrhizal fungi , Grain yield , Harvest Index , Drought Stress