Influence of chemical fertilizers and bioinoculants on growth and yield of sunflower (Helianthus annuus L.)

The present study was conducted to investigate and compare the effect of applying various levels of chemical fertilizers and bioinoculants on the growth and yield of sunflower during the 2017-2018 crop year in Hamedan, Iran. This study was executed as two factorial experiments, as a randomized complete block design in three repetitions. Chemical fertilizers containing nitrogen (N) and phosphorus (P) were used in the first experiment, and nitrogen-fixing (NI) and phosphate-solubilizing (BI) bioinoculants were used in the second experiment. The experimental treatments included applying a urea fertilizer (N-0=0, N-1=45, N-2=90 kg pure nitrogen/ha) and a triple superphosphate (P-0=0, P-1=40, P-2=80 kg pure phosphorus/ha), as well as a nitroxin biofertilizer (NI0=0, NI1=0.5, NI2=1 L/ha) and a biophosphorus (BI0=0, BI1=0.5, BI2=1 L/ha). The results indicated that the highest levels of leaf dry weight, number of seeds per head, head diameter, head weight, seed yield, and the plant's biological yield were obtained for the chemical treatment (N2P2) and biological treatment of (NI2BI2). Group comparisons between the chemical and biological treatments did not show a significant difference for any of the studied characteristics, therefore, the results of this study conclude that the investigated levels of bioinoculants could be appropriate alternatives to chemical fertilizers.