Effect of Different Levels of Drought Stress and Mycorrhiza on Yield of Safflower Cultivars

Safflower is known as valuable oil plant due to its high quality of seed oil and the presence of more than 90% of unsaturated fatty acids. Drought stress is the most important factor limiting crop yields in many parts of the world, including Iran. Coexistence with mycorrhizal fungi increases growth, improves yield, and increases plant resistance to a variety of environmental stresses, including drought. The aim of this study was to investigate the effect of coexistence with mycorrhiza on the tolerance of spring safflower cultivars at different levels of drought stress by measuring some quantitative and qualitative traits.

This experiment was conducted as a factorial-split plot based on randomized complete block design at research farm of Urmia agricultural high school during 2014 with three replications. The main plots (factor A and B) consisted of three levels of irrigation including optimum irrigation, moderate drought stress and severe drought stress and factor B included mycorrhiza in two levels: non-inoculation (control) and inoculation with mycorrhiza species Glomus mosseae. Sub plots (factor C) consisted of five spring safflower cultivars (Padideh, Gol Mehr, Goldasht, Safheh and Mexic).

The results of variance analysis showed that Severe drought stress compared to optimum irrigation reduced 1000-seed weight, number of seeds per head, number of head per plant, seed yield, oil yield and protein yield by about 29, 30, 33,58, 62 and 63%, respectively. Inoculation with mycorrhizal fungi compared to non-inoculation increased seed yield, chlorophyll index, protein yield, 1000-seed weight and biological yield by about 14, 13, 14, 5 and 39%, respectively.

One of the best methods for improving the quantitative and qualitative performance of safflower cultivars, especially under drought stress conditions, inoculation with mycorrhizal fungi is recommended. Also, in all three different levels of drought stress conditions, among the cultivars studied, Padideh cultivar was superior to other cultivars for yield and this cultivar is suitable for cultivation in this area.