KEANEKARAGAMAN RHIZOBAKTERI DAN POTENSINYA SEBAGAI PGPR (PLANT GROWTH PROMOTING RHIZOBACTERIA) PADA TANAH RHIZOSFER KAKAO (THEOBROMA CACAO L.) VARIETAS IR (FORASTERO) DAN VARIETAS HIBRIDA (TRINITARIO) DI PERKEBUNAN DESA SEKLOK, KABUPATEN SUMEDANG

• Main Author: Amalya Chairinida, Gita
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/47189
• Institution: Institut Teknologi Bandung

Cacao (Thebroma cacao L.) is the third-largest export agricultural commodity in Indonesia. Additionally, Indonesia is one of the largest exporter of cocoa, exporting 596,477 tons of cocoa beans in 2018 alone. West Java is one of the provinces that produces cacao, Sumedang being the one of a region that produces cacao. Cocoa demands were predicted to continue increasingch year from 2019-2025. It shows that high demand for cocoa must be followed by high cocoa production. Therefore, it is necessary to improve the quality and quantity of cocoa yield, one of which is the use of biofertilizer. Biofertilizer is a substance that contains living microorganisms, such as rhizobacteria. Rhizobacteria colonize the rhizosphere or the interior of the plant roots and promote growth and supply primary nutrients to the plant. Biofertilizer is an ideal alternative to chemical fertilizer because it is effective and safe for the environment. Rhizobacteria are commonly used as biofertilizer compositions. Rhizobacteria that can promote plant growth is called PGPR (Plant Growth Promoting Rhizobacteria). The purpose of this study are to compare the diversity of indigenous rhizobacteria from the rhizosphere of the IR (Forastero) and HB(Trinitario) variety of cacao trees in the Seklok Village cacao plantation in Sumedang and see its potential to be a PGPR (Plant Growth Promoting Rhizobacteria) to stimulate plant growth. Rhizobacteria were isolated with Nutrient Agar (NA) medium and their abundance were calculated with Total Plate Count method. The rhizobacteria isolates were screened for the ability of PGPR (Plant Growth Promoting Rhizobacteria) with IAA (Indole Acetic Acid) test, phosphate solubility test, and nitrogen fixation test. The most potential isolate was identified by the MALDI-TOF MS method. The result shows that there were 20 rhizobacteria isolates from IR (Forastero) cacao rhizosphere soil and 17 rhizobacteria isolates from HB (Trinitario) cacao rhizosphere soil. Based on Sorensen Similarity Index of 0.136, the rhizobacteria similarity between the two habitats have low species similarity. Rhizobacteria that have the ability to convert tryptophan to IAA are IR.1B, IR.2, IR.8, HB.13. HB.14, and HB.18. Rhizobacteria that have the ability to do phosphate solubilization are isolates IR.5, IR.7, IR.4, IR.17, HB.2, HB.3, HB.14, and HB.17. Rhizobacteria that have the ability to fix nitrogen into ammonia are IR.1B, IR.5, HB.4, and HB.14. Based on the three tests that were conducted, HB.14 (Bacillus megaterium) was found to be the most potential isolate to become PGPR due to its positive results.