Diazotrophic inoculation supplemented nitrogen demand of flooded rice under field conditions

Supplementing n fertilizer demand of flooded rice (oryza sativa l.) crop by integrated means is important area of research for economical and sustainable agriculture. for present field trial,three soil n rates (60,90,120 kg ha −1) were applied to main plots. before transplantation to randomized subplots,roots of rice seedlings were dipped for 1 h in water (control),azospirillum and azotobacter in 1:1 ratio (diazotrophs) or diazotrophs + 10 −5 m l-tryptophan (l-trp). compared with control of seedling treatment,diazotrophs alone or in combination with l-trp significantly (p≤0.05) increased straw and paddy yields at low (60 kg n ha −1) and medium (90 kg n ha −1) rates of n. however,paddy yield was only non-significantly different between 90 kg n ha −1 with diazotrophs alone and 120 kg n ha −1 with or without diazotrophs. at 90 and 120 kg n ha −1,most of the studied plant growth and nutrient accumulation responses were statistically at par between seedling treatments with diazotrophs and diazotrophs + l-trp. nitrogen application was the main factor that influenced n concentration in plant tissues. however,seedling treatments also significantly increased n and p concentration in rice straw and grain. maximum net value of the produce and value-to-cost ratio were achieved with diazotrophic inoculation at 90 kg n ha −1. conclusively,diazotrophic inoculation supplemented n demand of flooded rice by potentially fixing atmospheric n2 and influencing nutrient dynamics in soil. © 2015,university of agriculture. all right reserved.