Effect of combined use of fertilizer and plant growth stimulating bacteria Rhizobium, Azospirillum, Azotobacter and Pseudomonas on the quality and components of corn forage in Iran

Zea mays variety 704 (single cross) was studied to investigate effect of chemical fertilizers and growth-promoting bacteria on yield and yield components of corn ( Zea mays ). A factorial experiment was conducted in a completely randomized block design with three replications at Tehran-Varamin Research Farm (Iran) in 2017. The treatments were as follows: inoculation of the seeds with growth promoters in four levels: Rhizobium , Azospirillum , Azotobacter and Pseudomonas ; Rhizobium , Azospirillum and Pseudomonas ; Rhizobium , Azotobacter and Pseudomonas ; Azospirillum , Azotobacter and Pseudomonas and use of nitrogen (N) and phosphorus (P) fertilizers at four levels: no use, 1/3, 2/3, and 100 % recommended were applied. The results showed that the use of fertilizer was significant on the traits such as several leaves per plant, number of seeds per row, number of seeds per ear, plant height and forage yield at 1 % level. The results indicated that the highest forage yield of 33.78 t ha-1 was obtained from the interaction between the use of fertilizers and biological fertilizers, Rhizobium , Azospirillum , Azotobacter and Pseudomonas , which was 42 % higher than control.