Isolation, Screening and Characterisation of Plant Growth-Promoting Endophytic Bacteria from Weed Species

With the intervention of green revolution many of the high yielding varieties, pesticides and fertilizers were introduced in agriculture which resulted in gradual replacement of traditional agricultural practices to chemical farming but, the chemical farming not only deteriorated the soil health. In order to overcome the effects of the chemical farming, the biological means of crop production is gaining lot of importance. Among the biological means, the endophytic microorganisms are a class of microbes that live in internal plant tissues of apparently healthy host plant parts like roots, stems, leaves and seeds which play an important role in growth and development of the crop by nutrient solubilization, biological control and production of phytohormones. So far, the crop endophytes have been exploited more but, the weed endophytic bacteria are not concentrated much in crop production. Hence, there is a need to give attention on the use of the weed endophytic bacteria in agriculture. In an attempt to isolate, screen and characterize the plant growth promoting endophytic bacteria from roots and stems of selected weed species which are grown in cultivated areas of Shivamogga district, Karnataka, India. Out of 5 weed species, as many as twenty seven endophytic bacterial isolates were obtained and assessed for their plant growth promotional activities viz., phosphorus, potassium, zinc and silicon solubilization. Among 27 endophytic bacterial isolates tested, four isolates viz., SENDO – 5, SENDO – 6, SENDO – 17 and SENDO – 27 were efficient in phosphorus, potassium, zinc and silicon solubilization ability. Further, based on morphological and biochemical characters the efficient endophytic bacterial isolates were tentatively identified as Achromobacter and Citrobacter species. Scaleup studies are required to develop and evaluate the different formulations of the efficient endophytic bacterial isolates on different crops for their sustainable production.