Effect of Seed Priming with Plant Growth Promoting Rhizobacteria (PGPR) on Phyllochron and Leaf Appearance Rate of Barley (Hordeum vulgar L.) at Different Levels of Nitrogen

In order to investigate the effects of plant growth promoting rhizobacteria (PGPR) at various levels of nitrogen and phosphorus fertilizers on phyllochron and leaf appearance rate of barley (Hordeum vulgar L.)، an experiment was conducted at the Research Farm of Islamic Azad University of Ardabil during 2009 growing season. The combination of nitrogen fertilizer at three levels (0، 40، and 80 kg N/ha as urea) and phosphorus fertilizer (0، 30، and 60 kg P2O5/ha) were factorially assigned to the main plots and seed priming with plant growth promoting rhizobacteria (PGPR) at four levels (no priming، seed priming with Azetobacter chorchorum strain 5، Azospirillum lipoferum strain OF، and combination of seed priming with Azosprilium +Azetobacter) were assigned to the subplots. The results showed that phyllochron، leaf appearance rate، number of leaf per plant، leaf dry matter and leaf area index were significantly affected by nitrogen and phosphorus levels and seed priming with PGPR. With increasing nitrogen and phosphorus levels، the phyllochron decreased but rate of leaf appearance increased. Leaf appearance rate in seed priming with both Azospirillum+Azetobacter was more than Azospirillum or Azetobacter priming alone. Leaf dry matter was increased significantly in the combined treatment of seed priming with PGPR×levels of N and P fertilizers. Maximum leaf dry matter was obtained in the plots which had received the highest levels of nitrogen and phosphorus fertilizers in seed priming with Azospirillum compared to the control treatment. The highest number of leaf per plant and leaf area index were observed in seed priming with both Azospirillum +Azetobacter، and the least values of these parameters were recorded in no priming. Maximum number of leaf per plant and leaf area index were obtained at the highest levels of N and P fertilizers and the minima were observed in treatments with no fertilizer application. In all sampling stages، leaf area index in seed priming with PGPR was more than no priming (control). Thus، in order to increase leaf appearance rate، number of leaf per plant، and leaf area index، seeds priming with Azetobacter+Azospirillum at the highest levels of nitrogen and phosphorus fertilizers can be suggested.