Improvement in growth and alkaloid content of Rauwolfia serpentina on application of organic matrix entrapped biofertilizers (Azotobacter chroococcum, Azospirillum brasilense and Pseudomonas putida)

The field experiment was conducted to study the effect of conventional chemical fertilizer (urea),conventional biofertilizers (charcoal based) and organic matrix entrapped biofertilizer; (OMEB: a consortium of Azotobacter chroococcum, Azospirillum brasilense and Pseudomnas putida entrapped with clay soil, neem leaves, and cow dung in ratio of 1:1:1 and 15% saresh (plant gum of Acacia sp.) in various doses on growth parameters of Rauwolfia serpentina in terms of root length, shoot length, number of leaves, number of roots and fresh and dry weight of roots and shoots. Replacement of conventional chemical fertilizer by the consortium of biofertilizers (un-entrapped) increased plant growth in a dose dependent manner up to triple dose of the recommended dose (RD) of biofertilizers (1.80 kg ha-1). This increase in plant growth was not up to the level which appeared in the application of RD of urea. Entrapment of the same biofertilizers in an organic matrix mentioned above enhanced the plant growth similar to that observed for urea. The percentage increase of 9.57 and 7.54 in fresh weight (FW) and 11.93 and 11.12% in dry weight (DW) of shoot and 17.94 and 37.87% in FW of roots and 31.90 and 50.08% in DW of roots were recorded in 75 days old plant by the application of OMEB- triple dose over the conventional biofertilizers triple dose and recommended dose of urea. Conventional biofertilizers enhanced the availability of nitrate, nitrite and phosphate in the roots and leaves of the plant over application of urea as well as conventional biofertilizers. This formulation also increased alkaloid contents of in the roots of this plant. Microbial population of soil was also improved indicating enhanced soil fertility with application of OMEB. The results indicate that replacement of chemical fertilizers with microbial biofertilizers is possible with application of higher dose of biofertilizers entrapped into the organic matrix for the cultivation of medicinal plants like R. serpentina.