Standardization of dosage of liquid and cyst formulations of Azospirillum for different application methods

Abstract

Azospirillum bioinoculant is well known for its high nitrogen-fixing and plant growth-promoting characters. Carrier-based bioinoculants generally suffer from shorter shelf-life, poor quality, high contamination and low field performance. As an alternative, the liquid and cyst formulations of Azospirillum inoculants can play a significant role. Liquid and cyst formulations of Azospirillum were developed by adding amendments to the NFb broth and to MSM medium, respectively, which have longer shelf-life and tolerance to adverse conditions such as temperature and desiccation. The dosage of liquid and cyst-based formulations of Azospirillum for various inoculation methods such as seed treatment, seedling root dipping and soil application was standardized and their survival was studied. Inoculum levels of 10 ml/kg seeds, 150 ml/quantity of seedlings required for 1 ha and 300 ml/ha were found to be the optimum doses for seed treatment, seedling root dipping and soil application methods, respectively. The liquid and cyst formulations of Azospirillum have exhibited better adherence and survival on seeds, seedling roots and in the rhizosphere than the carrier-based form. These results indicated that there is substantial room to improve the liquid and cyst formulations of Azospirillum inoculant to obtain the desired benefits.

Effect of liquid and cyst formulations of Azospirillum with inorganic nitrogen on the growth and yield of rice

“…The Azospirillum culture was grown in an environmentally controlled shaker at 100 rpm at 30 o C. The liquid (Thamizh Vendan and Thangaraju, 2006) and cyst (Thamizh Vendan and Thangaraju, 2007a) formulations developed and standardized earlier were used in this study. The dosage of the formulations for various inoculation methods was also standardized (Thamizh Vendan and Thangaraju, 2007b). To evaluate the performance of the liquid and cyst formulations of Azospirillum, field experiments were laid out with the rice variety ADT-46 (short duration, 115 days).…”