Effects of Nitrogen and Seed Biopriming with Plant Growth Promoting Rhizobacteria (PGPR) on yield, Rate and Effective Grain Filling Period of Sunflower (Helianthus annus L. (

In order to evaluate the effects of nitrogen fertilizer and seed  biopriming with Plant Growth Promoting  Rhizobacteria (PGPR) on yield, rate and effective grain filling period of sunflower (Helianthus annus L.), a factorial experiment  was conducted based on randomized complete block design by three replications in field experimental University of Mohaghegh Ardabili in 2010. Factors were: nitrogen fertilizer in three levels (0, 80 and 160 kg N ha^-1) as urea and seed biopriming with plant growth promoting rhizobacteria in four levels containing, without priming (as control), seed biopriming with Azotobacter  chroococcum strain 5, Azospirillum  lipoferum strain OF, Psedomunasstrain 186. Results indicated that effect of treatment compound of nitrogen rates ×seed bio priming with 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 bio priming with PGPR. Response of grain yield wasn^,t the same for various levels of nitrogen fertilizer× seed bio priming with PGPR. The highest grain yield belonged to application of 160 kg N ha^-1  and seed priming  with  Azotobacter. Means comparison showed that treatment compounds N₁₆₀ × without priming with PGPR and N₈₀×seed priming with PGPR Azotobacter had similar grain yields. A two part liner model was used to quantifying the grain filling parameters. Various levels of nitrogen fertilizer×seed biopriming with PGPR affected all grain filling parameters significantly. Maximum grain weight, rate and effective grain filling period was obtained in high nitrogen rates and seed priming with PGPR. Thus, it can be suggested that in order to increasing of grain yield in climate conditions of Ardabil, should be applied sunflower seed bio priming  with Azotobacter.