PEMANFAATAN BAKTERI RHIZOBIUM TAHAN SALIN DAN KALSIUM UNTUK PENGEMBANGAN TANAMAN LEGUMINOSA PAKAN DI LAHAN PANTAI UTARA JAWA TENGAH

Eny Fuskhah, Ir.,M.Si., Prof. Dr. Ir. R. Djoko Soetrisno, M. Sc

2011 | Disertasi | S3 Ilmu Peternakan

Tujuan penelitian secara umum adalah mengkaji pemanfaatan wilayah pantai yang belum tereksplorasi untuk penanaman leguminosa pakan demi mendukung pengembangan bidang peternakan. Hasil kajian diharapkan dapat merekomendasikan suatu paket teknologi baru yang menguntungkan untuk pengembangan peternakan di wilayah pantai. Penelitian pertama dilakukan pengujian tingkat salinitas tanah di lima lokasi di Pantai Utara Jawa Tengah meliputi Semarang, Pekalongan, Jepara, Demak, dan Rembang. Hasil penelitian menunjukkan tingkat salinitas tanah bervariasi dari sangat rendah sampai sangat tinggi pada musim kemarau, bulan Juli 2006. Demak (Wedung) memiliki tingkat salinitas tanah paling rendah yaitu DHL (daya hantar listrik) 0,85 mmhos/cm, diikuti Jepara (Kedung) dengan DHL 2,2 mmhos/cm, Semarang (Tugu) DHL 6,4 mmhos/cm, Pekalongan (Pantai Pasir Kencana) DHL 11,4 mmhos/cm, dan tertinggi Rembang (Kaliori) DHL 17,5 mmhos/cm. Telah diperoleh pula isolat Rhizobium yang diisolasi dari bintil akar turi (Sesbania grandiflora), lamtoro (Leucaena leucocephala), dan calopo (Calopogonium mucunoides) tahan pada salinitas sangat tinggi yaitu 8.500 ppm NaCl setara dengan DHL 15 mmhos/cm. Penelitian kedua dilakukan uji asosiasi Rhizobium terseleksi dengan leguminosa pakan dalam kondisi tercekam salin di rumah kaca. Tanah salin yang digunakan berasal dari daerah pantai Tugu Semarang dengan DHL 6,4 mmhos/cm. Berbagai campuran isolat bakteri Rhizobium tahan salin diinokulasikan pada tiga golongan leguminosa berdasarkan selektivitasnya terhadap kebutuhan Rhizobium yaitu sangat selektif (lamtoro/Leucaena leucocephala), tidak selektif (Calopogonium mucunoides), dan selektif moderat (Centrosema pubescens). Percobaan menggunakan Rancangan Acak Lengkap pola Faktorial 4 x 3 dengan 3 ulangan. Faktor pertama adalah macam isolat, I1 = tanpa isolat, I2 = Isolat asal Calopogonium, I3 = isolat asal lamtoro, I4 = gabungan isolat asal Calopogonium dan lamtoro dan faktor kedua adalah jenis leguminosa, T1 = lamtoro, T2 = Calopogonium, T3 = Centrosema. Hasil penelitian menunjukkan semua isolat Rhizobium yang dicobakan mampu membentuk bintil akar efektif, dan cenderung meningkatkan pertumbuhan dan produksi leguminosa yang dicobakan. Pertumbuhan dan produksi leguminosa dipengaruhi faktor jenis tanaman. Tanaman lamtoro paling baik diberikan inokulum Rhizobium asal lamtoro, Calopogonium dengan Rhizobium asal Calopogonium dan Centrosema paling baik diberikan inokulum Rhizobium campuran asal lamtoro dan Calopogonium untuk pertumbuhannya. Penelitian ketiga mengkaji pengaruh gipsum dan Rhizobium pada tanaman lamtoro dan Calopogonium di lahan salin. Penelitian di kawasan pantai Morosari, Sayung, Demak dengan DHL tanahnya 20,45 mmhos/cm. Rhizobium yang digunakan tahan salin sampai 12.000 ppm NaCl setara dengan DHL 20 mmhos/cm. Percobaan menggunakan rancangan petakpetak terbagi 2 x 2 x 2 dengan 3 ulangan. Petak Utama adalah jenis leguminosa yaitu T1 = lamtoro, dan T2 = calopo. Anak petak adalah inokulasi Rhizobium yaitu I1 = tanpa inokulasi, dan I2 = inokulasi Rhizobium tahan salin. Anak-anak petak adalah penggunaan gipsum yaitu G1 = tanpa gipsum, dan G2 = dengan gipsum. Hasil penelitian menunjukkan bahwa Calopogonium tidak mampu bertahan hidup sampai minggu ke 13 pada tanah sangat salin dengan DHL tanah 20,45 mmhos/cm dengan persentase kematian mencapai 73,96%. Lamtoro masih bertahan hidup walaupun kerdil dengan persentase kematian 21,35%. Dapat disimpulkan bahwa leguminosa lamtoro lebih tahan ditanam pada tanah dengan tingkat salinitas tinggi dibandingkan leguminosa Calopogonium. Penggunaan gipsum dan inokulan Rhizobium cenderung meningkatkan pertumbuhan dan produksi leguminosa pada lahan salin.

The research aim in general was to investigate the unexplored coastal area to legume forage crops for developing livestock field. The result was hoped be able to recommend a new technology for developing livestock in coastal area. In the first study, assessment of soil salinity were conducted in five different locations of Northern Central Java Coast, namely Semarang, Pekalongan, Jepara, Demak, and Rembang. The research showed various level ranged from very low to very high of soil salinity in dry season, July 2006. Demak (Wedung) had the lowest soil salinity that equal to the electrical conductivity (EC) of 0.85 mmhos/cm, the next EC grade was Jepara (Kedung) of 2.2 mmhos/cm, Semarang (Tugu) of 6.4 mmhos/cm, Pekalongan (Pantai Pasir Kencana) of 11.4 mmhos/cm, and the highest Rembang (Kaliori) of 17.5 mmhos/cm. In this step was also able to isolate Rhizobium from turi (Sesbania grandiflora), lamtoro (Leucaena leucocephala), calopo (Calopogonium mucunoides) which were tolerant under high salinity of 8,500 ppm NaCl or equale to electrical conductivity of 15 mmhos/cm. In the second study, test of association selected rhizobium with forage legumes under saline stress condition were done in a glass house. The saline soil tested were taken from coastal area of Tugu Semarang with EC of 6.4 mmhos/cm. Various combination of tolerant saline Rhizobium bacteria isolate were inoculated to 3 groups legume based on its selectivity to Rhizobium need, namely high selectivity (lamtoro/Leucaena leucocephala), low selectivity (Calopogonium mucunoides), and moderate selectivity (Centrosema pubescens). The experiment arranged completely randomized design following factorial 4 x 3 in three times replication. The first factor was kind isolates: I1=without Rhizobium, I2=Rhizobium from calopo, I3=Rhizobium from lamtoro, I4=mix of Rhizobium from calopo and lamtoro. The second factor was kind of legumes: T1=lamtoro, T2=calopo, T3=centro. The results of the study showed, all isolate Rhizobium were able to form effective root nodules of legume and tended to increase growth and production of legumes. The growth and production of legumes were influenced by kind of plant factor. Lamtoro was exhibited growing well when inoculated with Rhizobium inoculum from lamtoro, either Calopogonium when inoculated with Rhizobium inoculum from Calopogonium, while Centrosema responded with Rhizobium inoculum combination from lamtoro and Calopogonium for their growth. The third study following split-split plot 2 x 2 x 2 designed with 3 replication was to investigate the influence of gypsum and Rhizobium to lamtoro and Calopogonium plant in saline soil. The research was held at Morosari Beach Sayung Demak that had electrical conductivity of 20.45 mmhos/cm. The current Rhizobium was tolerant from salinity up to 12,000 ppm NaCl. The main plot was kind of legumes, namely T1 = lamtoro, and T2 = calopo. Sub plot was inoculation rhizobium, namely I1 = without inoculation, and I2 = inoculation tolerance saline rhizobium. While the sub-sub plot, gypsum treatment namely G1 = without gypsum, and G2 = with gypsum. The result showed that Calopogonium was not able to survive to 13rd week in saline soil with EC of 20.45 mmhos/cm with percent of mortality 73,96%. Lamtoro was still survived even short with percent of death 21.35%. It can be concluded that tree legume lamtoro which planted in high level saline soil was more tolerant than cover crop legume Calopogonium. Gypsum and Rhizobium inoculation tended to increase growth and production of legumes in saline land.

Kata Kunci : Rhizobium, Lamtoro, Calopogonium, Centrosema, Salin, Gipsum.