effects of different nutrition systems and biofertilizer (pgpr) on phenology period yield and yield components of sunflower (helianthus annuus l.)

in order to study the effects of different nutrition systems (organic, chemical and integrated) and biofertilizer (pgpr) on phenology period, grain yield and its component in sunflower (helianthus annuus l.) an experiment was conducted using alestar cultivar at the research farm of college of agriculture, tarbiat modares university in 2007. five levels of nutrition systems including f1 (100% organic), f2 (75% organic + 25% chemical), f3 (50% organic + 50% chemical), f4 (25% organic + 75% chemical), f5 (100% chemical) in main plot and two levels of biofertilizer i1 (inoculation) and i0 (control) as subplot were used in a split plot arranged in a randomized complete block design with three replications. results showed that chemical treatment (100% n) decreased phenology period gdds but treatment (100% fym) increased it. different nutrition systems and biofertilizer significantly affected yield, plant height, biological yield, harvest index (hi), seed oil content, the results revealed that the maximum grain yield, plant height, biological yield, harvest index (hi) was recorded in integrated system f3 (50% organic + 50% chemical). the grain yield in integrated system was more than organic and chemical systems (f3›f4›f2›f5›f1). bacterial inoculants with pgpr (i1) showed an increase in grain yield and yield components when compared campared to the control.