Media Optimal untuk Bradyrhizobium japonicum Toleran Asam- Aluminium Memproduksi Asam Indol Asetat bagi Pertumbuhan Kedelai

Abstract

The demand on soybean recently increase either in quantity or in quality. However, Indonesia have not been soybean self-supporting yet, since low production of soybean especially on acid land. Nitrogen and micro-elements are very low, and aluminium (Al) toxicity become problem in acid land, as well as Bradyrhizobium japonicum (Bj) could not survived. Some of B. japonicum strains are able to syntheses Indole Acetic Acid (IAA) with tryptophan precursor and soybean symbiosis. The objectives of this research were: (1) to find optimal media for IAA production by tolerance acid-Al B. japonicum on the various tryptophan concentrate, and (2) to see the distribution of B. japonicum inoculant and their effects on soybean cultivar Tanggamus growth. Bradyrhizobium japonicum and tryptophan concentrations used in this experiment were Bj 11(wt), Bj 11(19), KDR 15(wt), and USDA 110, and 0.75 mM; 1.00 mM; 1.25 mM; 1.50 mM. For second experiment combination of B. japonicum and tryptophan concentrations, Bj 11 (wt) 1.00 mM tryptophan, Bj 11 (19) 1.50 mM tryptophan, KDR 15 (wt), 1.50 mM tryptophan, USDA 110 1.25 mM tryptophan from first experiment, and without Bj but plus 1.00 mM tryptophan utilized on Tanggamus of soybean at growth–pouch pH 4.5 using randomized completely design, in six replication. Bradyrhizobium japonicum Bj 11(wt) 1.00 mM and Bj 11(19) 1.5 mM tryptophan gave primary root and lateral root length of soybean longer, number of lateral root, and IAA content of soybean increase better than standar strain USDA 110.