Improvement of yield, yield components and oil quality in sesame (Sesamum indicum L.) by N-fixing bacteria fertilizers and urea

Experiments were conducted in 2009-2010 at the Agricultural and Natural Resources Research Center of Yazd, Iran, to study the effect of nitrogen levels and plant growth-promoting rhizobacteria (PGPR) containing Azotobacter sp. and Azospirillum sp. on seed yield, its components and quality traits of sesame cultivars. Treatments were arranged in a factorial experiment based on randomized complete block design with nitrogen rates (0 (control), 25 and 50kgNha(-1)), cultivars (Darab-14, GL-13 and local) and N-fixing bacteria levels (non-inoculation and inoculation) were applied with three replications. Nitrogen fertilizer significantly increased yield and yield components, but reduced oil content in 2010. Inoculating seeds with PGPR increased yield and yield components of sesame cultivars compared to the control treatment. Seed yield in PGPR inoculation with half a rate of N fertilizer treatment was more than seed yield in the full rate of N fertilizer without a PGPR inoculation treatment. N fertilizer and PGPR application significantly decreased saturated fatty acids (palmitic and stearic acid) while it significantly increased unsaturated fatty acids (oleic and linoleic acid). Oleic acid had a significant negative correlation with linoleic acid (r=-0.79). The result showed that an application of PGPR could be usefully applied to reduce use of chemical fertilizer.