Application of Herbicide in Paddy Fields Inoculated with ‎Azotobacter chroococcum

A field experiment was conducted at Rasht, in 2014, to investigate controlling weeds in native Hashemi cultivar paddy fields by different methods of herbicide applications and inoculated with Azotobacter chroococcum. The factorial experiment based on a randomized complete block design with three replicates was performed. Factors were Azotobacter application with two levels (inoculation with or without Azotobacter chroococcum) and weed management regimes with six levels (pretilachlor plus a supplementary hand weeding, bensulfuron methyl plus a supplementary hand weeding, and pretilachlor bensulfuron methyl plus a supplementary hand weeding, hand weeding during rice growing period no herbicide, un-weeded during rice growing period no herbicide). Results indicated that paddy rice yield was significantly increased by 16% after Azotobacter chroococcum inoculation. Rice paddy yield was significantly reduced in un-weeded plots compared to hand weeded and herbicide treated plots. ANOVA also revealed that there was no interaction effect between Azotobacter chroococcum applications and weed management regimes on paddy and biological yields, indicating that the herbicides had no adverse effect on Azotobacter efficiency in promoting growth and paddy yield of rice. Weed dry weight was reduced by 88, 91, 92, and 94 percentages in weeded plot and plots treated with pretilachlor, bensulfuron methyl, and pretilachlor bensulfuron methyl, respectively, compared to un-weeded plots. Azotobacter chroococcum inoculation had no significant effect on weed biomass. Overall, the result of this experiment confirmed the feasibility of chemical weed control in paddy fields inoculated with Azotobacter chroococcum.