Inokulasi Fungi Mikoriza Arbuskula untuk Meningkatkan Pertumbuhan Tanaman Ubi Kayu (Manihot esculenta Crantz) di Tanah Inceptisol

Abstract

Ubi kayu banyak ditanam di tanah Inceptisol. Budidaya tanaman di tanah tersebut menghadapi beberapa masalah, seperti kemasaman tanah yang cukup tinggi, kadar bahan organik yang rendah, dan kurangnya unsur hara esensial. Sebagai media tumbuh, kesuburan tanah Inceptisol dapat ditingkatkan dengan pemberian inokulan fungi mikoriza arbuskula (FMA). Fungi mikoriza arbuskula dapat menghasilkan enzim-enzim yang dapat melepaskan unsur hara yang terjerap di dalam tanah, sehingga membantu tanaman untuk memperoleh unsur hara yang terjerap. Fungi tersebut juga membentuk hifa eksternal yang akan memperluas jangkauan akar tanaman dalam mendapatkan unsur hara. Efektivitas FMA terhadap tanaman ubi kayu belum banyak dilaporkan. Penelitian ini bertujuan untuk mengisolasi dan mengkarakterisasi spora FMA dari rhizosfer ubi kayu, serta menyeleksi untuk mendapatkan inokulan FMA yang efektif dan efisien dalam meningkatkan pertumbuhan tanaman ubi kayu di tanah Inceptisol. Penelitian ini dilaksanakan dari bulan Mei-Desember 2021 di Balai Penelitian Tanah, Kampus Penelitian Pertanian, Jl. Tentara Pelajar No. 12, Bogor, Jawa Barat. Spora FMA diisolasi dari rhizosfer ubi kayu yang diambil dari tujuh kecamatan yang merupakan wilayah pengembangan ubi kayu yaitu Bogor Tengah, Dramaga, Tamansari, Cijeruk (Jawa Barat); Mojongsongo (Jawa Tengah); Percut Sei Tuan, Sei Rampah (Sumatera Utara). Spora FMA yang berhasil diisolasi, diidentifikasi dan diseleksi pada tanaman inang jagung dengan media tanam zeolit. Isolat FMA potensial diuji efektivitasnya pada tanaman ubi kayu di tanah Inceptisol menggunakan Rancangan Acak Kelompok. Terdapat delapan perlakuan yang diulang tiga kali sehingga diperoleh 24 unit perlakuan, yaitu M1 (NPK rekomendasi), M2 (Glomus manihotis), M3 (konsosium Acalauspora tuberculata dan G. rubiforme), M4 (Gigaspora sp.2), M5 (konsorsium G. manihotis, A. tuberculata, dan G. rubiforme), M6 (konsorsium G. manihotis dan Gigaspora sp.2), M7 (konsorsium A. tuberculata, G. rubiforme, dan Gigaspora sp.2), dan M8 (konsorsium G. manihotis, A. tuberculata, G. rubiforme, dan Gigaspora sp.2). Pada perlakuan M2 sampai M8, pupuk NPK diaplikasikan sebanyak 75% dosis rekomendasi. Data parameter pengamatan dianalisis ANOVA (Analysis of Varience) menggunakan program RStudio 4.1.1. Analisis ragam yang berbeda nyata kemudian dilanjutkan dengan analisis menggnakan uji BNJ taraf 5%. Spora FMA yang berhasil diisolasi dari rhizosfer tanaman ubi kayu sebanyak 19 jenis. Spora FMA diidentifikasi menjadi dua ordo, lima famili, dan tujuh genus. Jenis FMA yang potensial adalah Gigaspora sp.2, Acaulospora leavis, dan Septoglomus constrictum. Dari hasil uji efektivitas FMA terhadap tanaman ubi kayu di tanah Inceptisol diperoleh dua inokulan potensial yaitu G. manihotis dan inokulan konsorsium A. tuberculata, G. rubiforme, dan Gigaspora sp.2 yang efektif meningkatkan pertumbuhan tanaman ubi kayu pada delapan minggu setelah tanam.

Cassava is widely cultivated in Inceptisol soils. The cultivation of plants in these soils faces several problems, such as the high acidity, low organic matter content, and lack of essential nutrients. Inceptisol soil fertility can be increased by giving arbuscular mycorrhizal fungus (AMF) inoculants. As a growing medium, AMFs produce enzymes to release unavailable nutrients in the soil, thereby helping plants absorb nutrients. These fungi also form the external hyphae, which expand the reach area of plant roots to absorb nutrients. There were limited studies of the effectiveness of AMF on cassava. This study aimed to isolate and characterize AMF spores from the cassava rhizosphere, as well as to select AMF inoculants that are effective and efficient in increasing cassava plant growth in Inceptisol soils. The research was conducted from May to December 2021 at the Soil Research Institute, Agricultural Research Campus, Jl. Tentara Pelajar No. 12, Bogor, West Java. Spores of AMF were isolated from cassava rhizosphere obtained from seven sub-districts which are development areas of cassava, namely Central Bogor, Dramaga, Tamansari, Cijeruk (West Java); Mojongsongo (Central Java); Percut Sei Tuan, Sei Rampah (North Sumatra). The AMF spores were identified and selected using corn as a host plant with zeolite media. Furthermore, the potential AMFs were tested their effectiveness in cassava plants in Inceptisol soil using The Randomized Block Design. There were eight treatments which repeated three times in order to obtain 24 treatment units. The treatments were M1 (recommended NPK), M2 (G. manihotis), M3 (consortium A. tuberculata and G. rubiforme), M4 (Gigaspora sp.2), M5 (consortium G. manihotis, A. tuberculata, and G rubiforme), M6 (consortium G. manihotis and Gigaspora sp.2), M7 (consortium A. tuberculata, G. rubiforme, and Gigaspora sp.2), and M8 (consortium G. manihotis, A. tuberculata G. rubiforme, and Gigaspora sp.2). For the M2 to M8 treatments, 75% of NPK fertilizers were applied at the recommended dose. Observational parameter data were analyzed by Analysis of Variance using the RStudio 4.1.1 program. The analysis of variance resulted in significantly different were then analyzed using the BNJ test at the 5% level. There were 19 species of the AMF spores that were successfully isolated from the rhizosphere of cassava plants. The AMF spores were identified into two orders, five families, and seven genera. The potential AMF species were Gigaspora sp.2, Acaulospora leavis, and Septoglomus constrictum. The results of the effectiveness test of AMF against cassava plants in Inceptisol soil showed that there were two potential AMF inoculants effective in increasing the growth of cassava plants at eight weeks after planting in Inceptisol soil, namely the single Glomus manihotis and the consortium inoculants Acaulospora tuberculata, Glomus rubiforme, and Gigaspora sp.2.