This research was conducted to investigating of effect of different vermicompost substitutions (0, 25, 50, 75%) on yield and seed mucilage content of Plantago psyllium in a greenhouse experiments. In reproductive phase, spike number per plant, seeds number per spike, thousand seed weight, seed yield and seed mucilage properties were recorded. Results showed that 25% vermicompost substitution promoted the highest seed number per spike and thousand seed weight but the highest number of spikes per ...