Karakterisasi bakteri diazotrof dan pengaruhnya terhadap pertumbuhan tanaman kedelai (Glycine max L. Merrill)

Abstract

One of the challenges to increased soybean yields is the high demand for nitrogen. The average N uptake reaches up to 219 kg N/ha. So far, the N supply has been obtained from chemicals fertilizers that are not environmental-friendly. Diazotroph bacteria as candidates of biological fertilizers can support the implementation of sustainable agricultural practices and soybean self-sufficiency in Indonesia. The aims of this research were to understand the morphological and physiological characteristics of three diazotroph bacteria from The Agricultural Microbiology Laboratory Research Center of Biology Indonesian Institute of Science (LIPI) (NFB₄, NFB₁₀) and Indonesian Culture Collection (InaCC) (InaCC B₁₄₁₂) and to investigate the effects of each diazotroph bacteria inoculant on soybean plant growth as an exploration effort to the best diazotroph bacteria. The results indicated that NFB₄, NFB₁₀, and InaCC B₁₄₁₂ had quite different colony morphological characteristics, but all of them were Gram-negative, rod-shaped bacteria. Apart from their nitrogen-fixing capability, they also had various capabilities at once, such as ammonia producing, phosphates solubilizing, IAA producing, ACC deaminase producing, and siderophore producing. All of them increased root length and root dry weight of soybean plant significantly (P ≤ 0,05), they also increased shoot length, shoot dry weight, number of nodules, leaf chlorophyll content, and number of soybean pods, albeit not significantly.