Rhizobacteria Consortium Improves Growth, Yield, and Phytochemicals In Robusta Coffee (Coffea canephora L.)

NI Luh Suriani^1*Mohammed Alzahrani^2,3Fahd Nasr³Lina M Alneghery³Dewa Ngurah Suprapta¹I Nyoman Suarsana¹Ni Made Delly Resiani^1,4Riyazali Sayyed⁵JAYANTHI BARASARATHI⁶Ting Seng Ho⁷Yulmira Yanti⁸

• ¹Biology Department, Faculty of Mathematics and Natural Science, Udayana University,, Bali, Indonesia
• ²College of Medicine, Imam Mohammad Ibn Saud Islamic University, Riyadh, Saudi Arabia
• ³Imam Muhammad ibn Saud Islamic University, Riyadh, Saudi Arabia
• ⁴University of Technology Malaysia, Johor Bahru, Johor Darul Takzim, Malaysia
• ⁵University of Nizwa, Nizwa, Oman
• ⁶INTI International University, Nilai, Negeri Sembilan Darul Khusus, Malaysia
• ⁷Back2Nature Organic Farm, Kuala Pilah, Malaysia
• ⁸Andalas University, Padang, West Sumatra, Indonesia

Coffee is among the most sought-after and valued commodities because it has a high market value and serves as a soothing beverage. However, organically grown coffee remains limited.Most coffee farmers still use chemical fertilizers and pesticides, which, when misused, can harm both the environment and human health. Therefore, alternative methods are needed to produce healthier crops, such as utilizing rhizobacteria, which are environmentally friendly and safe for human health. Through this study, rhizobacteria treatment was applied to coffee plants to enhance growth, phytochemical content, and antioxidant activity. This study aims to determine the influence of rhizobacteria on the growth, production, and phytochemical content of Balinese robusta coffee plants. The research utilized a randomized group approach with four treatments, six repetitions, and three units, resulting in 72 experimental plants. F0 represents the control group with untreated soil, while F1, F2, and F3 correspond to treatments with 2% Bacillus nitrificans, 2% Bacillus velezensis, and a consortium of 2% Bacillus nitrificans and 2% Bacillus velezensis, respectively. The results indicated that the F1, F2, and F3 treatments showed a notable distinction was observed in comparison to the control. The F3 treatment proved to be the most efficient in enhancing growth, antioxidant activity, alkaloid content, tannin levels, caffeine concentration, and coffee production, whereas the F2 treatment resulted in the highest flavonoid content. Both types of rhizobacteria have the ability to generate IAA, facilitate nitrogen fixation, and solubilize phosphorus. Moreover, all four rhizobacteria are capable of colonizing the roots of Robusta Bali coffee. The two rhizobacteria, B. nitrificans and B. velezensis, can function as biofertilizers and biostimulants for Robusta coffee plants in Bali, as they enhance growth, yield, and phytochemical content. Combined, these rhizobacteria produce better results than the control and single treatments, as they generate more biofertilizers and biostimulants. Therefore, these rhizobacteria are highly suitable for supporting sustainable agriculture.