MULTIFUNCTIONAL MUTANTS OF Azospirillum sp. WITH ENHANCED CAPABILITY OF SOLUBILIZING PHOSPHORUS, FIXING NITROGEN AND PRODUCING INDOLE ACETIC ACID

Azospirillum sp. have long been known as biofertilizer for plant growth because of its capability to produce phytohormones and fix nitrogen from the atmosphere. Multifunctional Azospirillum strain Aj Bandung 6.4.1.2 isolated in 2009 from cauliflower (Brassica oleracea) rhizosphere in Lembang, Bandung, West Java, was capable of fixing nitrogen, solubilizing tricalcium-phosphate, and producing phytohormone indole acetic acid (IAA). The study aimed to modify the multifunctions of Azos-pirillum sp. for better capability of fixing N2, solubilizing P, and producing IAA using ethyl methanesulfonate and 1-methyl-3-nitro-1-nitrosoguanidine (EMS) mutagen. The study was conducted at Indonesian Center for Agricultural Biotechnology and Genetic Resources Research and Development (ICABIOGRAD) in 2010. The results showed that this strain was genetically mutagenized using EMS for better performance in solubilizing P, fixing N2 (nitrogenase activity), and producing phytohormone (IAA). The optimum concentration and the length of incubation time for the process have been determined. Nine selected mutants with increasing capability to solubilize P (determined by clear-zone formation on Pikovskaya’s medium) have been characterized for nitrogenase activities and IAA production compared to wild type Aj Bandung 6.4.1.2. The effect of mutagenesis on IAA produc-tion and nitrogenase activities varied among the mutans. Two mutants, AzM 3.7.1.16 and AzM 1.7.2.12, showed superiority in the production of IAA, while two mutants, AzM 1.5.1.14 and AzM 3.7.1.15, were superior in nitrogenase activities. The EMS mutagenesis of Azospirillum sp. showed enhanced dissolving capa-bility of unsoluble phosphate (tricalciumphosphate) and increased IAA production and nitrogenase activity.

Effect of antagonistic bacteria and its formulation to control fusarium wilt disease on shallot

Biocontrol of pathogenic fungi using antagonistic bacteria isolated from the soil (rhizosphere) is expected to suppress plant diseases to obtain good quality of yield, and thus support sustainable agriculture. The study aimed to formulate and scale up the production of rhizosphere-based bacterial biopesticides that effective in suppressing the onset of Fusarium wilt disease caused by Fusarium oxysporum f.sp. cepae on shallot. The experiment to evaluate the effectiveness of biocontrol agents against Fusarium wilt disease was carried out employing shallot cv. ‘bima curut’ in the field (Patrol-Indramayu,West Java), from May to August 2018 growing season. The experimental plot of 1.20 m x 18 m, was prepared using plant spacing of 15 × 10 cm. The solid formulation of kaolin-based bacteria (containing bacterial cells of 109 CFU/mL) was applied with variation of four concentrations range from 0.3125 to 2.5 mL/L. The experiment was arranged in randomized block design with four replications. Shallot beginning at 30 days old-plant was sprayed three times at one-week intervals. The results showed that the disease intensity was significantly lower than in control. Under natural infection, the spraying application of a bacterial isolate (DSB2) using kaolin formulation (107 CFU/mL) with a formula concentration of 1.25 mL/L could reduce the disease intensity. Tuber yield of formula treatments was significantly higher than that of control. Thus, the use of bacterial formula as environmental-friendly biocontrol agent in this study might be further recommended in controlling Fusarium wilt disease on shallots

Effect of indigenous microbes on growth and blister blight disease of tea plant

The role of the tea commodity in the economy of Indonesia is quite strategic. Various types of microorganisms in nature have been known to increase the benefit of the root function, suppress disease, and accelerate plant growth. This study aimed to determine the potential of indigenous bacteria (Azoto II-1, Acinetobacter sp., bacteria Endo-5, bacteria Endo-65 and Endo-76) on the growth of tea plants and their potential in increasing resistance to blister blight disease. The test of microbes’ potential effect on growth and blister blight was conducted in Gambung, West Java in an experimental field using a randomized block design (RBD) with six treatments and each treatment was replicated four times. The composition of the treatments was: A) Endo-5; B) Endo-65; C) Endo-76; D) Azoto II-1; E) Acinetobacter sp.; and F) control (without microbes). Bacterial suspension was applied directly to the soil at a dose of 2 l · ha−1. The bacterial suspension was applied six times at 1 week intervals. The results of field observations indicated that the intensity of blister blight decreased in all treatments but did not significantly differ from the control. Meanwhile, the results of Acinetobacter sp. treatment in tea shoots was 17.26% higher than the control

Effect of antagonistic bacteria and its formulation to control fusarium wilt disease on shallot

Biocontrol of pathogenic fungi using antagonistic bacteria isolated from the soil (rhizosphere) is expected to suppress plant diseases to obtain good quality of yield, and thus support sustainable agriculture. The study aimed to formulate and scale up the production of rhizosphere-based bacterial biopesticides that effective in suppressing the onset of Fusarium wilt disease caused by Fusarium oxysporum f.sp. cepae on shallot. The experiment to evaluate the effectiveness of biocontrol agents against Fusarium wilt disease was carried out employing shallot cv. ‘bima curut’ in the field (Patrol-Indramayu,West Java), from May to August 2018 growing season. The experimental plot of 1.20 m x 18 m, was prepared using plant spacing of 15 × 10 cm. The solid formulation of kaolin-based bacteria (containing bacterial cells of 109 CFU/mL) was applied with variation of four concentrations range from 0.3125 to 2.5 mL/L. The experiment was arranged in randomized block design with four replications. Shallot beginning at 30 days old-plant was sprayed three times at one-week intervals. The results showed that the disease intensity was significantly lower than in control. Under natural infection, the spraying application of a bacterial isolate (DSB2) using kaolin formulation (107 CFU/mL) with a formula concentration of 1.25 mL/L could reduce the disease intensity. Tuber yield of formula treatments was significantly higher than that of control. Thus, the use of bacterial formula as environmental-friendly biocontrol agent in this study might be further recommended in controlling Fusarium wilt disease on shallots