Kelimpahan dan Uji Kemampuan Rhizobium dari Lahan Gambut untuk Peningkatan Pertumbuhan Acacia crassicarpa di PT. Mayangkara Tanaman Industri
UMMI ROSYIDAH, Dr. Ir. Handojo H Nurjanto, M.Agr.Sc., IPU; Dr. Ir. Eny Faridah, M.Sc., IPM.
2023 | Tesis | S2 Ilmu Kehutanan
Indonesia memiliki lahan gambut seluas 13,43 juta ha yang sebagian telah dimanfaatkan sebagai lahan pertanaman dalam bentuk Hutan Tanaman Industri. Lahan gambut memiliki karakteristik berupa lahan tergenang, anaerob, pH serta unsur hara rendah, sehingga membutuhkan pengelolaan khusus. Upaya pengelolaan ini perlu dilakukan untuk memberikan kondisi optimal bagi pertumbuhan tanaman. Nitrogen merupakan unsur hara yang terbatas bagi tanaman yang sebagian besar diperoleh melalui symbiosis dengan mikroorganisme tanah salah satunya rhizobium. Isolasi bakteri rhizobium dari lahan gambut diperlukan agar lebih sesuai dikembangkan menjadi biofertilizer bagi tanaman di lahan gambut. Penelitian ini dilakukan untuk mengevaluasi populasi dan mendapatkan isolat bakteri rhizobium terpilih yang akan dikembangkan sebagai pupuk hayati, serta mengetahui pengaruhnya terhadap pertumbuhan tanaman di persemaian.
Indonesia has of
13.43 million hectares of peatland, some of which have been utilized as
plantation land in form of Industrial Plantation Forests. Peatlands have
characteristics waterlogged landscape, anaerobic condition, a low pH, and
limited nutrient availability, necessitating distinctive management approaches.
To ensure optimal condition for plant growth, it is necessary to implement
management strategy. Nitrogen is a limited nutrient for plants mostly obtained
by fixation from the atmosphere through soil microorganisms, one of which is
rhizobium. Isolation of rhizobium from peatlands is needed to reduce habitat
selection so that they can be developed into biofertilizers to improve plant
growth. This study aims to evaluate the population and obtain selected
rhizobium bacteria to be developed as biofertilizers, and to determine their
response to plant growth in the nursery.
Plantation of A.crassicarpa stands ranging from 1-4 age classes with a spacing of 3x2.5 meters were used in this study. For each age class, three replication of 20x20 m sample plots were established to obtain data on growth, environmental conditions, soil samples, and root nodules. Isolation was conducted from root nodules using the discontinue streak method with pH medium treatment, while the abundance was analysed by employing the microdroplet method. The isolates obtained were characterized and tested for nodule formation for 2 months to obtain selected isolates. Six selected isolates were propagated using yeast extract-mannitol liquid media and formulated into a biofertilizer. The biofertilizer were then inoculated employing 3 shade treatments (P1, P2, and P3) with 60 replications was carried out for 3 months. The assessed parameters were the percentage of germination, percentage of survival, height, biomass, and weight of nodules.
The findings
revealed that the height of A. crassicarpa aged 1, 2, 3, and 4 years
were 4.2, 7.6, 12.7, and 12.2 m, respectively,
while their corresponding diameters were 3.6, 8.3, 10.5, and 13 cm. The
cultivated land has a groundwater level of 25-45 cm, a soil
moisture content of 347%-580% and a bulk densityt of 0.064-0.101 gr/cm3. The abundance of rhizobium in peatlands
ranged from 104 to 107 cfu/g
soil. A total of 73 rhizobium isolates were obtained, comprising 24 isolates
(KU 1), 24 isolates (KU 2), 18 isolates (KU 3), and 6 isolates (KU 4). The six
selected isolates, namely isolate A (1-1-2 (5)), B (1-2-2 (5)), D (1-3-1 (5)), E
(1-3-2B (5)), C (1-2-2B (6)), and F (2-1-1B (6)), demonstrated the ability to
form nodules in 39-44 days after inoculation, with 6 to 11 nodules. The
inoculation of isolate A, B, D, and E resulted in fairly good response in terms
of plant growth, encompassing seedling height, above-ground and below-ground
biomass, as well as the number of root nodules.
Kata Kunci : rhizobium, peatland, A.crassicarpa, nursery