RESPONSE OF MAIZE TO FOLIAR APPLICATION OF ZINC AND AZOTOBACTER INOCULATION UNDER DIFFERENT LEVELS OF UREA FERTILIZER

In order to investigate the effects of zinc and Azotobacter on maize production properties under different regime of urea as mineral fertilizer, an experiment was conducted at research field of Sari Agricultural Sciences and Natural Resources University during the cropping season of 2014. The nitrogen mineral fertilizer in 100, 200 and 300 amounts of kg urea ha^-1, Azotobacter (inoculation and non-inoculation) and foliar application of zinc (Zn1 = 1000 mg l^-1 zinc sulfate, Zn2 = 500 mg l^-1 zinc sulfate and Zn3 = 0 mg l^-1) were considered as the applied treatments. Grain yield, biological yield (dry matter), and total protein content of each treatment were assessed. Results indicated that foliar applications of Zn had a significant effect on all studied traits. The highest grain yield was related to Zn1 treatment in each urea application and also between biological fertilizer treatments the highest yield was observed in inoculation treatment. Between all studied treatments the maximum grain yield (with 10.23 ton ha^-1) was obtained through non-inoculation treatment × Zn1 for 300 kg urea ha^-1. The highest biological yield was observed in Zn1 + inoculation treatment. There were no significant differences between Azotobacter inoculation and non-inoculation for each level of zinc applications in 300 kg urea ha^-1 treatment. Finally, it might be concluded that using of mineral fertilizer could be reduced by combining some management strategies in maize production.