Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.4, No.3, 2014 35 Effectiveness of Rhizobacteria to Reduce Rice Blast Disease Intensity Dewa Ngurah Suprapta*, Valente Quintao, and Khamdan Khalimi Laboratory of Biopesticide Faculty of Agriculture Udayana University, Jl. PB. Sudirman Denpasar Bali Indonesia. *Corresponding author’s email : biop@dps.centrin.net.id Abstract Rice blast disease caused by Magnaporthe grisea Barr (anamorf Pyricularia grisea Sacc. synonym Pyricularia oryzae Cav.) is one of important diseases for rice cultivation in Indonesia. Five isolates of rhizobacteria isolated from the rhizospheres of rice in Bali were tested for their effectiveness to reduce the rice blast disease intensity on rice cultivar Ciherang under green house condition. All isolates were formulated in liquid formulas which were respectively contained bacterial suspension of Enterobacter agglomerans Ch2D, Xanthomonas luminescens Ch3D, Enterobacter agglomerans Ch4B, E. agglomerans Gg14D and Serratia liquefaciens Gh13D. Results of this study showed that all five formula of rhizobacteria effectively reduced the rice blast intensity on rice cultivar Ciherang. The rice blast intensity on plants treated with rhizobacteria were varied from 13.96 to 19.44%, while the disease intensity on control was 33.56%. Formula containing bacterial suspension of E. Agglomerans Gg14D resulted in the lowest blast disease intensity and the highest yield per hill. The yield increment resulted from this treatment was 40% when compared to control. This result suggested that E. agglomerans Gg14D is one of promising candidate for bio-control agent to manage rice blast disease. However, the field trial is needed in order to evaluate the stability and effectiveness of the rhizobacteria formula under field condition at several localities. Keywords: rhizobacteria, rice blast disease, disease intensity 1. Introduction Rice blast disease caused by Magnaporthe grisea Barr (anamorf Pyricularia grisea Sacc. synonym Pyricularia oryzae Cav.) is one of important diseases for rice cultivation in Indonesia and other rice growing areas (BPS, 2010, Kato, 2001, Chin, 1975). The yield losses caused by the disease vary by areas, between 1- 100% in Japan (Kato, 2001), 70% in China, and 21-37% in Bali Indonesia (Suprapta and Khalimi, 2012), in South America and Southeast Asia between 30-50% (Baker et al., 1997; Scardaci et al., 1997). Three strategies has been known to control the rice blast disease such as cultural practice, grow the resistant cultivar and the use of synthethic fungicides (TeBeest, 2007; Ghazanfar et al., 2009; BPTP, 2009; IRRI, 2010). The use of resistant cultivas has been known to be the most effective strategy, however, Pyricularia oryzae has been known to develop the new race rapidly that may breakdown the rice resistance. Thus the use of resistant cultivar is limited to certain place and time (BPTP, 2009). Based on this reason, the use of resistant cultivar should be combined with other control strategy which is more effective and friendly to the environment. One of the strategy is the use of antagonists as bio-control agent to suppress the development of rice blast disease. Soil microorganisms those associated with the rhizospheres of plants have been known to contribute in many processes in the soil which in turn may influence the plant growth (Tilak et al., 2005). The interaction of microorganism and plant in the rhizospheres could be neutral, beneficial or harmful to the plant as they may cause plant diseases (Husen, 2003). Several important rhizobacteria have been reported as plant growth promoting agent and antagonists against plant pathogens namely Azospirillum, Alcaligenes, Arthrobacter, Acinetobacter, Acetobacter, Azotobacter, Bacillus, Bradyrhizobium, Burkholderia, Enterobacter, Erwinia, Flavobacterium, Pseudomonas, Proteus, Rhizobium and Serratia (Kloepper et al., 1989; Glick, 1995; Tilak et al., 2005; Naureen et al., 2005; Egamberdiyeva, 2005; Bhawsar, 2011). Khan et al. (1997) reported that antagonistic rhizobacteria Actinoplanes spp. could control the fungal disease caused by Pythium ultimum on sugar cane. Huang and Wong (1998) found that Burkholderia cepacia A3R could control Fusarium graminiearum on wheat. Burkholderia cepacia PHQM and Pseudomonas fluorescens VO61 was reported to be effectively control Fusarium sp. and Pythium sp. on corn (Hebber et al., 1998). Lewis and Larkin (1998) reported Cladorrhinum foecundissinum could be used as bio-control agent to control pathogenic fungi Phythium ultimum and Rhizoctonia solani on egg plant and chili pepper. Bacillus spp. could control the pathogenic fungi Rhizoctonia solani and Gaeumannomyces graminis var. tritici on wheat (Ryder et al., 1999). Other workers reported that Bacillus subtilis BACT-D could control Pythium aphandermatum on tomato (Utkhede et al., 1999) while Pseudomonas fluorescens VO61 could control Rhizoctonia solani on rice (Vidhyasekaran and Muthamilan, 1999). This study was done in order to test the effectiveness of Enterobacter agglomerans, a rhizobacterium isolated from rhizosphere of rice in Bali to control the rice blast disease caused by Pyricularia oryzae.