Response of Sunflower Seed Quality Characteristics to Plant Growth
Promoting Rhizobacteria under Water Stress

In order to study the quality of sunflower in response to PGPR and different levels of urea under water stress condition, an experiment was conducted during 2006 growing season at the Eslam Abad-Gharb Agricultural Research Station, Kermanshah province, Iran. The experimental design was split-plot laid out in RCB with three replications. The main plots were three levels of irrigation [irrigation at 85% field capacity (I1), irrigation at 70% field capacity (I2) and irrigation at 55% field capacity (I3)] and sub plots were six levels of fertilizer [control (C), recommended rate of N (125 kg urea/ha) (N), inoculation with Azotobacter chroccocum&Azospirillum lipoferum (AA), AA+100% recommended rate of N (AA100), AA+75% recommended rate of N (AA75) and AA+50% recommended rate of N (AA50))]. Water stress significantly affected protein percentage but fertilizer treatment had high significant effect on this trait. The I3 and AA100 treatments significantly increase of protein percentage. The highest and lowest oil percentages were obtained from I1AA100 and I3C treatments, respectively. Combination treatments of I3C increased palmitic and stearic acid in seeds. The lowest percentage of palmitic and stearic were obtained from I1AA treatment. The I1AA50 and I1AA treatments significantly increased oleic and linoleic acid respectively, whereas these fatty acids decreased in I3AA100 and I3AA75 treatments, respectively. Overall, drought stress significantly decreased oil percentage, oleic and linoleic acids but increased palmitic and stearic acids in the seeds. Application of biofertilizers with urea significantly increased the oil, protein and unsaturated fatty acids in sunflower seeds. Because of the low price and positive effect of biofertilizers on sunflower seed quality, utilization of these fertilizers are therefore highly recommended in sunflower culture.