Azotobacter and azospirillum inoculants for nitrogen economy in vegetable cultivation

Abstract

The study on Azotobacter and Azospirillum inoculants for nitrogen economy in vegetable cultivation was conducted at College of Agriculture, Vellayani, Thiruvananthapuram during 1994-1996. Two sets of experiments consisting of pot and field trials were conducted for this purpose. Pot culture experiments with amaranthus showed that, plant height, root biomass, leaf area index and yield were significantly high in the treatment combination of Azospirillum inoculation along with FYM and 75 percent fertilizer nitrogen (N3FYM+AS). Flowering time was also significantly delayed in this treatment. Among Azotobacter treatments also plant height, leaf area index and yield were significantly high in the treatment receiving 75 percent nitrogen along with FYM and Azotobacter inoculation (N3FYM+AB). In brinjal while Azospirillum inoculation along with 75 percent nitrogen and FYM (N3FYM+AS) could significantly increase yield and increase plant height and root biomass production, there were no significant difference among Azotobacter treatments on yield. In chilli also Azospirillum treatment coupled with vermicompost and 100 percent nitrogen (N4 VEC+AS) was significantly increasing number of branches, number of fruits and yield. Whereas there were no significant differences among Azotobacter treatments on yield of chilli. When the individual effect of organic manure and biofertilizer application for all the three crops were studied, no significant differences were obtained between two biofertilizer treatments except for some delay in flowering time in amaranthus due to Azospirillum inoculation. But FYM application had favorable effects in most of the plant growth and yield parameters of all the three crops. The selected treatments from pot culture experiments were evaluated under field conditions for all the three crops. Maximum yield for amaranthus was obtained in Azotobacter treatment with FYM and 75 percent fertilizer nitrogen (N3FYM+AB), which also had a significant increase in plant height. For brinjal, the Azotobacter treatment recervmg FYM and 75 percent nitrogen (N3FYM+AB) produced maximum plant height, number of branches, number of fruits and yield. But keeping quality of fruits was significantly high in Azotobacter treatment with full dose of vennicompost and 75 percent fertilizer nitrogen (N3 VECF+AB). For chilli, Azospirillum treatment receiving full dose of vermicompost and 100 percent nitrogen (N4VECF+AS) produced maximum yield which also has got maximum plant height. Keeping quality of fruits was also significantly high in this treatment. The population of bacteria, fungi, actinomycetes, Azospirillum and Azotobacter were significantly high in most of the treatments receiving either Azospirillum or Azotobacter inoculants and organic manure supplements.