Effects of Seed Priming with Plant Growth Promoting Rhizobacteria (PGPR) on Grain Yield, Fertilizer Use Efficiency and Dry Matter Remobilization of Sunflower (Helianthus annus L.) with Various Levels of Nitrogen Fertilizer

In order to evaluate the effects of seed priming with Plant Growth Promoting Rhizobacteria (PGPR) on grain yield, fertilizer use efficiency and dry matter remobilization of sunflower with various levels of nitrogen fertilizer, a factorial experiment was conducted based on randomized complete block design with 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 priming with Plant Growth Promoting Rhizobacteria in four levels containing (without priming as control, seed priming with Azotobacter chroococcum strain 5, Azospirillum lipoferum strain OF, Psedomunasstrain 186). Results indicated that nitrogen levels and seed priming with Plant Growth Promoting Rhizobacteria (PGPR) had significant effects on all of characteristics studied. Grain yield, plant height, head diameter, seed number per head, yield and oil percentage increased with increasing of nitrogen fertilizer and seed priming with PGPR. Response of grain yield wasnt the same for various levels of nitrogen fertilizer and seed 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. Nitrogen use efficiency decreased with increasing of nitrogen application. But, seed priming with plant growth promoting rhizobacteria produced nitrogen use efficiency more than no priming. Maximum nitrogen use efficiency (41.7 kg/kg) was recorded at treatment compound of N80 × priming with Azotobacter and minimum of it (21.09 kg/kg) was recorded at N160 × without priming with PGPR. Means comparison showed that maximum of dry matter remobilization in grain yield (32.98 %) was obtained in no application of nitrogen× without seed priming with PGPR and minimum of it (21.77 %) was recorded at the highest level of nitrogen application× seed priming with Azotobacter. Thus, it can be suggested that in order to increasing of grain yield and nitrogen use efficiency be applied 80 kg N/ha in seed priming with Azotobacter in climatic conditions of Ardabil.