157 Journal of Biological Control, 29(3): 157-161, 2015 Research Article M. SURENDRAN, G. S. KANNAN 1 , KAMALA NAYAR 2 and S. LEENAKUMARY Rice Research Station, Moncompu-688 503, Thekkekara P.O., Alleppey District, Kerala, India. 1 Department of Plant Protection, Faculty of Agriculture and Animal Husbandary, Gandhigram Rural University, Gandhigram-624 302, Dindigul,Tamil Nadu, India. 2 Instructional Farm, College of Agriculture, Vellayani-695 522, Trivandrum, Kerala, India. *Corresponding author E-mail: surenpath@yahoo.co.in Biochemical characterization of native fluorescent pseudomonads and its suitable carrier material for mass multiplication in Kuttanad ecosystem (Article chronicle: Received: 02-05-2015; Revised: 16-07-2015; Accepted: 25-09-2015) ABSTRACT: Bacterial antagonist fluorescent pseudomonads for sheath blight disease were isolated from different locations in Kuttanad region. Three effective strains viz., PF 43, PF 46 and PF 47 were tested along with standard culture P 1 against sheath blight disease of rice under glass house condition. The confirmation tests viz., physiological and biochemical characterization of the efficient isolates were car- ried out at Rice Research Station, Kerala Agricultural University, Moncompu. Various physiological tests on growth at different pH, Iron toxicity and Aluminium toxicity level showed that the isolate PF 43 grew at pH ranging from 1.0 to 14 and tolerated upto 1000 ppm of iron toxicity and 90 ppm of aluminium toxicity level. The biochemical tests indicated that three efficient isolates were confirmed as gram negative, rod shaped, fluorescent in King’s B medium and positive response for growth at 4º C, Levan formation, Gelatin liquefaction and Catalase tests. However, there was a negative response for growth at 41ºC, Methyl red, VogesProskaur and Indole tests. Thus, based on morphological and biochemical characteristics, the isolated strains were identified to be Pseudomonas fluorescens. P. fluorescens PF 43 product survived upto 150 days with required population of 1.01 to 1.63 x 10 8 cfu per g in talc, dolomite and gypsum based formulations. At 240 days of storage, 1 x 10 7 cfu were detected in talc, dolomite and gypsum based formulations. The cheap and easily available carrier material, gypsum and dolomite can be used for mass production of native P. fluorescens and is recommended to 66,000 ha rice growing tracts of Lower, Upper and Karilands of Kuttanad regions like Alleppey, Kottayam and Pathanamthitta District for ecofriendly manage- ment of diseases. KEY WORDS: Dolomite, gypsum, Pseudomonas fluorescens, rice, sheath blight INTRODUCTION The sheath blight of rice caused by Rhizoctonia solani Kuhn. was first noticed in Kuttanad in 1969. It is now rat- ed as one of the most serious diseases of rice in the tract. The locally accepted variety, Uma occupies a vast area of Kuttanad since fifteen years, but it is highly susceptible to sheath blight disease. The farmers periodically apply many fungicides to control the disease leading to environmental pollution. Hence, for ecofriendly management biocontrol agents have gained considerable importance for the control of sheath blight disease in recent years. Many fluorescent pseudomonads have been reported to induce systemic re- sistance against sheath blight disease. For effective biocon- trol of soil borne plant pathogens, the biotic agent should possess high level of rhizosphere competence, fungicide resistance and should grow under wide range of pH, tem- perature, iron and aluminium toxicity. A successful biocon- trol agent should possess many desirable characters. All the characters may not be present in a single strain. The objective of the present study was to isolate efficient native fluorescent pseudomonads, characterization of isolates and identify suitable carrier material for increasing the shelf life of the bioformulation. MATERIALS AND METHODS Comparative efficacy of screened fluorescent pseu- domonads isolates on control of sheath blight incidence under green house condition Talc based formulation of the best three effective iso- lates (PF 43, PF 46, PF 47 ) obtained from in vitro screening test against fungal pathogen (R. solani) and the standard culture P1, of fluorescent Pseudomonas sp., was prepared