Rasti Saraswati
Balai Penelitian Tanah

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SOYBEAN SEEDLING ROOT GROWTH PROMOTION BY 1-AMINOCYCLOPROPANE-1-CARBOXYLATE DEAMINASE-PRODUCING PSEUDOMONADS Husen, Edi; Wahyudi, Aris Tri; Suwanto, Antonius; Saraswati, Rasti
Indonesian Journal of Agricultural Science Vol 10, No 1 (2009): April 2009
Publisher : Indonesian Agency for Agricultural Research and Development - MOA

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Abstract

Pseudomonad producing 1-aminocyclopropane-1-carboxylate(ACC) deaminase (E.C.4.1.99.4) has been known to promoteplant growth by lowering ethylene biosynthesis in higher plants,which can be induced by indole-3-acetic acid (IAA) production.The objective of this study was to examine the ability of IAAproducingPseudomonas isolated from local soil environment(rhizosphere of soybean grown in Plumbons agricultural areain Cirebon, West Java, Indonesia) to promote soybean root growthin relation to their ACC deaminase activities. The experimentswere conducted in growth room and Laboratory of Soil BiologyResearch, Indonesian Soil Research Institute, Bogor, from Januaryto August 2008. Soybean seeds were inoculated by immersing theseeds for 1 hour in bacterial cell suspension containingapproximately 108-109 cells ml-1. The seeds were then germinatedfor 2 days before planting in growth pouches containing sterilizeddistilled water. All treated and untreated seeds were grown for7 days in growth room at 24°C with 1300 lux of light intensityfor 12-hour followed by a 12-hour dark period at 22°C. ACCdeaminase activity of the isolates was assayed based on their abilityto grow in Dworkin-Foster’s salt minimal medium containingammonium sulfate or ACC as a source of nitrogen. Thirteen outof 81 isolates tested significantly increased soybean root lengthand weight, up to 50% from untreated plants. Of 13 isolates,11 demonstrated ACC deaminase activities. Two isolates thatdid not show ACC deaminase activities had lower capacity toproduce IAA. The results suggest that the effectiveness of IAAproducingPseudomonas in promoting the growth of the soybeanseedlings is associated with their ACC deaminase activities orthey produce IAA at low levels.
CHARACTERIZATION AND QUALITY ASSESSMENT OF INDONESIAN COMMERCIAL BIOFERTILIZERS Husen, Edi Husen; Simanungkalit, R.D.M.; Saraswati, Rasti; ., Irawan
Indonesian Journal of Agricultural Science Vol 8, No 1 (2007): April 2007
Publisher : Indonesian Agency for Agricultural Research and Development - MOA

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Biofertilizers currently sold in the market are not labeled witha distinct quality standard. As such, farmers may buy low qualitybiofertilizers, which can reduce their profit and trust on the benefitof biofertilizers. This paper presents the characteristics of variousproducts of commercial biofertilizers as well as farmers’ knowledgeand experience on the products. The study was carried out in2004-2006 by collecting and analyzing data on registered commercialbiofertilizers, checking their availability at the market(39 agricultural shops), and interviewing farmers on their knowledgeand experience on the use of biofertilizers on various farmingsystems in Bandung District, West Java (86 respondents) andSemarang District, Central Java (77 respondents). The quality ofbiofertilizers was tested in the laboratory based on microbialdensity and its functional (phenotypic) traits. The study showedthat amongst various brands of biofertilizers commercialized,41 brands of them have been officially registered as commercialproducts. Two brands of other biofertilizers found in agriculturalshops were registered as organic or inorganic fertilizers. In general,each biofertilizer contained two or more microbial strains andwas claimed to have multiple functions. However, most of them(>90%) were not labeled with expiry date information. Macronutrientcontents (NPK) of some microbial carriers were almostequal to those of organic fertilizers. Around 38% of respondentsin Bandung knew biofertilizers and less than 10% have ever usedthem. In Semarang, however, familiarity and personal experienceof the respondents were much lower, i.e. 10% and 3%, respectively.About 67% and 50% of agricultural shops in Bandung andSemarang sold biofertilizers, respectively. Laboratory analysesshowed that microbial density of five biofertilizers tested waslower than that of product specification, although most of themwere positive for N-fixing and P-solubilizing traits. Some microbialstrains contained less than 103 cfu based on the dilution leveltesting. These figures imply the urgent need to improve theexisting quality standard system of biofertilizers including itscontrol mechanisms.