Effect of biofertilizers and chemical fertilizers on yield and yield components of pumpkin (Cucurbita pepo L. Convar. pepo Var. styriaca)

In order to study the effect of biofertilizers and chemical fertilizers on yield, yield components, chlorophyll and photosynthesis rate of pumpkin (Cucurbita pepo L.), an experiment was conducted in a randomized complete blocks design with 8 treatments and 3 replications at Research Farm of Kurdistan University in 2009. Treatments included: control (N1), nitroxin (free-living nitrogen fixing bacteria) (N2), phosphate solubilizing bacteria (N3), nitroxin + phosphate solubilizing bacteria (N4), chemical fertilizer (urea 120 kg ha-1 + mono super phosphate 150 kg ha-1) (N5), 50% chemical fertilizer + nitroxin (N6), 50% chemical fertilizer + phosphate solubilizing bacteria (N7), 50% chemical fertilizer + nitroxin + phosphate solubilizing bacteria (N8). Results indicated that the fertilizer treatments had significant effects on chlorophyll, photosynthesis rate, fruit diameter, fruit fresh weight and fruit and seed yield. Maximum seed yield (97.97 gr/m2) was obtained from (N8) treatment and the highest fruit yield (6272.2 and 5790/5 gr/ha), photosynthesis rate (15.56 and 14.05 µmol m-2 s-1 CO2) and chlorophyll (53.06 and 50.08 SPAD values) were obtained from (N8) and (N6) treatments respectively. The fertilizer treatments had no significant effects on the 1000 seed weight and number of fruits per stem. According to the results, it is concluded that application of biofertilizers along with 50% chemical fertilizer could reduce the need for chemical fertilizers and the highest seed and fruit yield would be obtained.