POPULASI BAKTERI PENAMBAT NITROGEN SIMBIOTIK PADA RIZOSFER BEBERAPA VEGETASI PIONIR DI LAHAN BEKAS ERUPSI GUNUNG API MERAPI

TRI NUGROHO JATI, Ir. Handojo H. Nurjanto, M. Agr. Sc.

2014 | Skripsi | BUDIDAYA HUTAN

Lahan bekas erupsi Gunung Api Merapi ditumbuhi jenis-jenis vegetasi pionir, antara lain Leguminosae. Pengaruh rhizosfer beberapa vegetasi pionir terhadap bakteri rhizobium di lahan tersebut belum diketahui. Penelitian ini bertujuan untuk Mengetahui populasi bakteri Rhizobium pada rizosfer beberapa vegetasi di area yang terkena dampak erupsi Gunung Api Merapi. Penelitian dilakukan di Kaliadem dan Kalitengah Lor. Sampel diambil dari Rizosfer vegetasi (Trema orientalis, A. decurrens, Pennisetum purpureum, dan Ptridophyta) dan tanah tanpa vegetasi di lokasi, masing-masing 3 ulangan. Variabel vegetasi yang diamati antara lain jumlah dan efektivitas bintil akar. Populasi bakteri penambat nitrogen dihitung dengan metode Plate count. Bakteri yang tumbuh diisolasi, diidentifikasi dan diuji kemampuan pembentukan bintil akarnya pada semai Acacia decurrens. Analisa yang digunakan adalah deskriptif kuantitatif. Bintil akar terbanyak dan efektif dijumpai di vegetasi Trema orientalis (25,6 bintil/tanaman, 83,68%) diikuti A. decurrens (12 bintil/tanaman, 75,04%) di daerah Kaliadem. Di daerah Kalitengah Lor, bintil akar dijumpai pada tumbuhan A. decurrens (10,3 bintil/tanaman, 46,46%). Rerata jumlah bakteri Rhizobium di rizosfer vegetasi di tapak Kalitengah Lor sebesar 3,23 x 106 CFU/g dan tanpa vegetasi sebesar 2,44 x 106 CFU/g. Rerata jumlah bakteri Rhizobium di rizosfer di tapak Kaliadem sebesar 1,91 x 106 CFU/g dan tanpa vegetasi sebesar 1,27 x 105 CFU/g. Hasil isolasi diperoleh 24 isolat. Isolat Rhizobium (6 isolat) membentuk koloni berbentuk bulat, cembung, berwarna putih sampai putih susu, dan memiliki morfologi sel batang pendek dan gram negatif. Uji pembentukan bintil akar pada semai A. decurrens belum mampu membentuk bintil akar.

Land affected by Merapi volcano eruption was occupaid by pioneer vegetations, such as Leguminosae. Rhizosphere effect of these vegetations on Rhizobium population was not known yet. The purposes this research was to know Rhizobium populations in the rhizosphere of vegetation in areas affected by Merapi volcano eruption. This research was conducted in Kaliadem and Kalitengah Lor. Samples were taken from the rhizosphere of vegetations (Trema orientalis, A. decurrens, Pennisetum purpureum, dan Ptridophyta) and soil without vegetation, each with 3 replications. Variable vegetation observed were amount and effectiveness of root nodules. Nitrogen-fixing bacteria population was counted by the Plate count method. The coloni were isolated, identified and tested for the ability of root nodule formation in Acacia decurrens seedlings. The analysis used was quantitative descriptive analysis. The greatest effective number and nodules were found in Trema orientalis (25.6 nodules/plant, 83.68%) followed by A. decurrens (12 nodules/plant, 75.04%) growing in Kaliadem area. In Kalitengah Lor area, root nodules were found in A. decurrens (10.3 nodules/plant, 46.46%). The mean number of Rhizobium in the rhizosphere of vegetation in Kalitengah Lor was 3.23 x 106 CFU/g and without vegetation 2.44 x 106 CFU/g. The mean number of Rhizobium cell in the rhizosphere in Kaliadem was 1.91 x 106 CFU/g and no vegetation was 1.27 x 105 CFU/g. Isolation has obtained 24 isolates. Rhizobium isolates (6 isolates) formed spherical colonies, convex, white to milky white in color, and have a short rod cell morphology and gram negative. Root nodule formation experiment in A. decurrens seedlings found that the isolates did not form root nodule.

Kata Kunci : Rhizobium, Vegetasi, Rizosfer, Gunung Api Merapi