Journal of Biology, Agriculture and Healthcare www.iiste.org ISSN 2224-3208 (Paper) ISSN 2225-093X (Online) Vol.11, No.16, 2021 14 Efficacy of Rhizobacteria to Promote the Growth and Increase the Yield of Several Rice Cultivars Dewa Ngurah Suprapta* I Gede Rai Maya Temaja Laboratory of Biopesticide, Faculty of Agriculture Udayana University Jl. PB. Sudirman Denpasar Bali Indonesia Abstract Rice is still play important role as staple food for most of Indonesian population; consequently Indonesia is greatly relying on rice production to maintain food security. This plant is commonly cultivated with intensive use of synthetic agrochemicals such as synthetic chemical fertilizers and pesticides. However, the improper use of agrochemicals may result in adverse effects to the environment including biotic and abiotic components. This study was conducted to evaluate the efficacy of rhizobacteria formulation to promote the growth and increase the yield of four rice cultivars that commonly grown in Indonesia i.e. Ciherang, Cigeulis, Inpari 33, and IR64. Experiment was done in a green house with three concentrations of rhizobacteria formulation i.e. 0%, 1%, and 2% (v/v). Several parameters were observed in this study such as seedling height, leaf chlorophyll content of seedling, plant height at 50 days after transplanting (DAT), leaf chlorophyll content at 50 DAT, number of tillers per plant at 50 DAT, number of productive tillers per plant, and yield per plant. Results showed that significant interactions were observed between rice cultivar and concentration of rhizobacteria formulation in all parameters observed. Rice cultivar IR64 consistently showed superior growth and yield among four rice cultivars tested. Except for cultivar IR64, rhizobacteria concentration at 2% showed superior results compared to 1% and 0% for all parameters observed. This study proved that rhizobacteria formulation containing Stenotrophomonas maltophilia Sg3 and Enterobacter cloacae Al7Kla effectively promoted the growth and increase the yield of four rice cultivars that commonly cultivated in Indonesia, suggested that this rhizobacteria formulation is promising bio-agent to be used for rice production in Indonesia. Keywords: Rhizobacteria, plant growth promotion, rice yield DOI: 10.7176/JBAH/11-16-03 Publication date:August 31 st 2021 1. Introduction Plant production is relying on the use of synthetic chemical fertilizers to provide enough macro nutrients such as N, P, and K. These macro nutrients are also very important in rice production in Indonesia. The use of macro nutrients in particular N is not entirely absorbed by the rice plant due to the poor root system. Consequently, part of N will remain in the soil; some lost because of evaporation, leaching through water runoff and potentially pollute water bodies in rivers as well as lakes. In addition, excessive use of N results in the plant growth become weak and susceptible to several plant pathogens such as blast disease caused by Magnaporthe grisea Barr (anamorf Pyricularia grisea Sacc., synonym Pyricularia oryzae Cav.) (Kato, 2001). Based on this reason, it is necessary to find bio-agents in particular from plant rhizospheres that posse’s ability to enhance the formation of root hairs and improve the root system. Hence will increase the efficiency of absorption of nutrients. Rice productivity in Indonesia was about 5.14 ton/ha (BPS, 2012) which is relatively lower than other countries such Australia 8.22 ton/ha, Japan 5.85/ton/ha and China 6.06 ton/ha (USDA, 2004). They gave of rice productivity in Indonesia with other rice growing countries suggested that there is a chance to increase the rice productivity through the use of rhizobacteria from rhizospheres of plants. Several rhizobacteria have been known to have plant growth promotion potential such as Pseudomonas, Enterobacter, Azospirilum, Azotobacter, Burkholderia, Bacillus and Serratia (Alam et al., 2001; Vidyasekaran et al., 1997; Khalimi et al., 2012). Seed treatment with Pseudomonas fluorescens strain Pf1 obviously increased the rice yield (Vidhyasekaran et al., 1997). Rice plant inoculated with Rhizobium sp. IRBG74 increased the rice yield by 11,6% (Biswas et al., 2000), while Alam et al. (2001) found that treatment by soaking the root of rice seedling for 24 h with the suspensions of Azotobacter nigricans, A.armeniacus, Bacillus sphaericus, B. megaterium, Enterobacter and Xhantobacter increased the rice yield by 15,03%. Other study done by Khalimi and Suprapta (2012) showed that the treatment with Pantoea agglomerans isolates PaJ and BS2a isolated from the rhizosphere of groundnut increased the yield of rice cultivar Cicih Medang Selem (a local rice variety of Bali) by 154.17% when compared to control. As rhizobacteria may have specificity in their host plant, in this study a formulation of rhizobacteria containing Stenotrophomonas maltophilia Sg3 and Enterobacter cloacae Al7Kla was tested for its potential to promote the growth and increased the yield of 4 (four) rice cultivars that commonly cultivated in Indonesia. The aim of this study is to know variation of responses among 4 (four) rice cultivars against rhizobacteria treatment.