Potensi Bakteri Penambat Nitrogen dalam Menginduksi Pertumbuhan Padi dan Kompatibilitasnya terhadap Ralstonia pickettii TT47.

Abstract

Tanaman padi merupakan tanaman pangan yang membutuhkan unsur nitrogen (N) yang tinggi dalam proses pertumbuhannya dibandingkan dengan unsur lainnya. Rizosfer tanaman padi merupakan habitat dari bakteri penambat nitrogen. Bakteri penambat nitrogen berperan dalam stimulasi pertumbuhan tanaman dengan meningkat nitrogen bebas di atmosfer. Infeksi patogen Rhizoctonia solani mudah ditemukan pada padi dengan sistem budidaya yang menggunakan bahan tanam varietas unggul dan pemupukan secara intensif. Bakteri Ralstonia pickettii merupakan salah satu agens hayati yang dapat menghambat pertumbuhan cendawan Rhizoctonia solani. Penelitian ini bertujuan mendapatkan isolat bakteri penambat nitrogen asal rizosfer padi dalam menginduksi pertumbuhan padi serta kompatibilitas dengan R.pickettii TT47. Tahapan penelitian yang dilakukan meliputi pengambilan sampel rizosfer padi pada lokasi yang berbeda, isolasi dan karakterisasi bakteri asal rizosfer padi pada media Nitrogen-free Bromthymol Blue (NFB), uji keamanan hayati, uji kompatibilitas isolat bakteri rizosfer padi dengan R.pickettii TT47, uji kemampuan isolat bakteri rizosfer padi dalam menginduksi pertumbuhan tanaman, serta identifikasi molekuler. Isolat bakteri asal rizosfer padi yang berhasil diisolasi pada media NFB semi padat sebanyak 64 isolat dan sebanyak 47 isolat lolos uji keamanan hayati. Terdapat 27 isolat yang kompatibel terhadap R.pickettii TT47. Perlakukan isolat A14, B25, C25, dan D25 menunjukkan pertumbuhan tajuk tanaman padi tertinggi yang mewakili setiap lokasi A, B, C,dan D. Identifikasi molekuler menunjukkan bahwa isolat A14, B25, dan C25 memiliki kekerabatan paling dekat dengan spesies Klebsiella variicola, Klebisella sp., dan Enterobacter sp. Isolat D25 belum berhasil diidentifikasi secara molekuler berdasarkan sikuen gen 16S rRNA.

The rice plant is a food crop that requires a high nitrogen (N) element in the growth process compared to other elements. The rhizosphere of rice plants is the habitat of nitrogen-fixing bacteria. Nitrogen-fixing bacteria play a role in stimulating plant growth by fixing free nitrogen from the atmosphere. Infection of the pathogen Rhizoctonia solani is commonly observed in rice cultivation systems that use high-yielding varieties and intensive fertilization. Ralstonia pickettii bacteria is one of the biological agents that suppress the growth of Rhizoctonia solani. Rice rizosphere is the soil around plant roots and is the habitat of many microorganisms that are beneficial for plant growth including nitrogen fixing bacteria. This study aims to obtain nitrogen fixing bacteria from rice rhizosphere for inducing growth of rice plant and compatible to R. pickettii TT47. The research methods included collecting samples of rice rhizosphere in different locations, isolation and characterization of bacteria from rice rhizosphere on Nitrogen-free bromothymol blue (NFB) media, biosafety test, compatibility test of isolates of bacteria from rice rhizosphere to R. pickettii TT47, test the isolate ability of bacteria from rice rhizosphere for inducing plant growth, and molecular identification of potential isolates of bacteria. Bacteria isolates from the rice rhizosphere that were successfully isolated on semi-solid NFB media totaled 64 isolates and 47 isolates passed the biosafety test. There were 27 isolates that were compatible with R. pickettii TT47. Among of those nitrogen fixing bacterial isolates, the isolates A14, B25, C25, and D25 showed the highest growth of rice plant height. Molecular identification showed that isolates A14, B25, and C25 had the highest similarity with Klebsiella variicola, Klebisella sp., and Enterobacter sp. Isolate D25 has not been successfully identified by molecular based on 16S rRNA gene sequences.