Study of qualitative and quantitative yield and some agronomic characteristics of sunflower (Helianthus annus L.) in response of seed inoculation with PGPR in various levels of nitrogen fertilizer

In order to study the qualitative and quantitative yield and some agronomic characteristics of sunflower (Helianthus annus L.) in response to seed inoculation with PGPR under various levels of nitrogen fertilizer, a factorial experiment was conducted based on a randomized complete block design with three replications in field experimental University of Mohaghegh Ardabili during growing season of 2009-2010. Factors were nitrogen fertilizer in three levels (0, 80 and 160 kg N ha-1) as urea and seed inoculation with plant growth promoting rhizobacteria in four levels containing, without inoculation (as control), seed inoculation with Azotobacter chroococcum strain 5, Azospirillum lipoferum strain OF, Psedomunas strain 186. Results indicated that nitrogen levels and seed inoculation with Plant Growth Promoting Rhizobacteria (PGPR) had significant effects on all of characteristics studied (except grain 1000 weight and stem diameter). Grain yield, plant height, head diameter, seed number per head,, yield and oil percentage, yield and protein percentage increased with increasing of nitrogen fertilizer and application of seed inoculation with PGPR. Response of grain yield wasnt the same for various levels of nitrogen fertilizer and seed inoculation with PGPR. The highest grain yield belonged to application of 160 kg N ha-1 and seed inoculation with Azotobacter. Means comparison showed that treatment compounds N160 × without inoculation with PGPR and N80 × seed inoculation with PGPR Azotobacter had similar grain yields. Thus, it can be suggested that in order to increasing of grain yield seed should be inoculated with Azotobacter bacteria × 80 kg N/ha in conditions of Ardabil region.