Effect of Different Fertilization Systems on Yield and Seed Mineral Elements of Pumpkin

To investigate the effects of bio-chemical and organic fertilizers on yield and seeds NPK contents of pumpkin (Cucurbita pepo var. styriaca)، an experiment was conducted at the Research Farm of Kurdistan University in 2009 growing season. Treatments were included 1) control، 2) seeds inoculated with free-living N fixing bacteria (NFB)، 3) seeds inoculated with phosphate-solubilizing bacteria (PSB)، 4) chemical fertilizer (C)، 5) organic fertilizer (O)، 6) NFB + PSB، 7) NFB+ 50% O، 8) NFB+ 50% C، 9) PSB + 50% O، 10) PSB + 50% C، 11) 50% O + 50% C، 12) NFB+ PSB + 50% O، 13) NFB+ PSB + 50% C، 14) NFB+ PSB + 50% O + 50%. The highest value of nitrogen concentration was observed in the NFB+ 50% C and NFB+ PSB+ 50%C treatments. The highest potassium concentration was found in the NFB+ 50% C treatment. The maximum phosphorous concentration was observed in PSB+ 50%C. The maximum seed yield was obtained from the treatment that pumpkin seeds inoculated with free-living N (NFB) and phosphate-solubilizing bacteria (PSB) + 50% organic fertilizer. The highest fruit yield was obtained from NFB+ PSB+ 50%C+ 50%O. It was concluded that application of biofertilizers in combination with 50% chemical and organic fertilizers، reduced the use of chemical fertilizers and produced higher seed and fruit yield.