Effect of different soil fertilizing agents on growth and yield of isabgol and black seed as two medicinal plants

In the first experiment the influence of vermicompost (2.5 and 5 ton.ha-1), cow manure (10 and 20 ton.ha-1) and humic acid application (1 and 2 kg.ha-1) combined with control was studied on qualitative and quantitative indices of isabgol based on a randomized complete block design. In the second study the effects of Sulphur (0, 150 and 300 kg.ha-1), thiobacillus bacteria (50:1 weight ratio of sulfur and bacteria) and cow manure (0 and 30 ton.ha-1) was evaluated on yield and yield components of black seed. Results showed that the effect of experimental factors was significant only on number of tiller, number of spike and SPAD reading in isabgol. The highest amounts of tiller and spike (5.6 and 48.5 number, respectively) was obtained by 2 kg.ha-1 humic acid application, while their lowest (3.8 and 31.6 number, respectively) was belonged to control treatment. Application of cow manure and humic acid increased partially the swelling factor of seeds. In addition, the highest seed yield (3.76 g per plant or 1038 kg.ha-1) was obtained at the rate of 2 kg.ha-1 humic acid usage. In the second experiment, the impact of experimental factors was not significant on black seed medicinal plant growth indices. However, almost all of studied criteria were improved by cow manure consumption, so that finally the seed yield of the plant was 292 and 243 kg.ha-1 in application and no-application cow manure treatments, respectively. overall, our results revealed that isabgol and black seed are two low-input medicinal plants in terms of nutrients requirements.