effect of plant growth promoting rhizobacteria (pgpr) application, nitrogen and zinc sulphate fertilizer on yield and nitrogen uptake in rapeseed (brassica napus l.)

in order to study the effects of simultaneous application of znso4 and biological fertilizer, azotobacter chroococcum and azospirillum brasilense, on grain yield and nitrogen uptake efficiency in rapeseed (brassica napus l.), cv. hyola308, a field experiment was conducted as split plot factorial based on randomized complete block design at research field of faculty of agricultural sciences, university of guilan, iran, during growing season of 2007-2008. results showed that urea fertilizer, znso4 fertilizer and biological fertilizer had significant effects on nitrogen uptake and accumulation. maximum grain yield (2568 kg.ha-1) were obtained in 150kgn + znso4+ bio treatment. maximum accumulation of nitrogen in rosette stage (4.9%) and nitrogen content of grain (3.6%) was obtained in 150 kg n.ha-1n + znso4 + bio. maximum nitrogen uptake efficiency and nitrogen use efficiency (0.86 and 29.56 kg.kg-1, respectively) were obtained in 50 kgn.ha-1n + znso4 + bio. in regard to significant effects of znso4 and biological fertilizer with lower n rate and high nitrogen uptake efficiency of rapeseed, it seems that the ability of uptake and use of nitrogen fertilizers was greater for seed formation in the presence of znso4 and biological fertilizer in rapeseed, cv. hyola308. the most important of mechanisms of pgprs is increase the bioavailability of mineral nutrients with biological nitrogen fixation and soluble phosphorus and potassium that lead to economize nitrogen fertilizer in rapeseed production and minimizing environmental pollution risk.