RASTI SARASWATI
Indonesian Soil Research Institute

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Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of bacterial leaf blight (BLB), is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD) with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants i RATIH DEWI HASTUTI; YULIN LESTARI; ANTONIUS SUWANTO; RASTI SARASWATI
HAYATI Journal of Biosciences Vol. 19 No. 4 (2012): December 2012
Publisher : Bogor Agricultural University, Indonesia

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.4308/hjb.19.4.155

Abstract

Xanthomonas oryzae pv. oryzae (Xoo), a causal agent of bacterial leaf blight (BLB), is one of the most important pathogens of rice. The effectiveness of ten Streptomyces spp. isolates in suppressing Xoo disease was assessed in planta and in vitro. In planta experiments were carried out in a greenhouse and arranged in a randomized completely block design (RCBD) with three replications. Twenty treatments were tested which included plants inoculated with both Streptomyces spp. and Xoo, and plants inoculated with only Streptomyces spp. Plants inoculated with Xoo and sprayed with a chemical bactericide, and plants inoculated with only Xoo served as positive controls, whereas plants not inoculated with either Streptomyces spp. or Xoo were used as negative controls. The results showed that the effect of endophytic Streptomyces spp. on BLB disease expressed as area under disease progress curve (AUDPC) was not significantly different to that on control plants (P > 0.05). However, plants inoculated with endophytic Streptomyces spp. were significantly taller and produced higher tiller number than control plants (P < 0.05). Streptomyces spp. isolate AB131-1 gave the highest plant height. In vitro studies on biocontrol mechanisms of selected Streptomyces spp. isolates showed that isolate LBR02 gave the highest inhibition activity on Xoo growth, followed by AB131-1 and AB131-2. Two isolates (AB131-1 and LBR02) were able to produce chitinase, phosphatase, and siderophore which included biocontrol characteristics. Morphological and colonization studies under SEM and light microscopy confirmed that the three isolates were endophytic Streptomyces spp. from different species. These studies found that the paddy plant which was inoculated with endophytic Streptomyces spp. AB131-1 and infected by Xoo could increase the height of plant and number of tillers.
CHARACTERIZATION AND QUALITY ASSESSMENT OF INDONESIAN COMMERCIAL BIOFERTILIZERS Edi Husen Husen; R.D.M. Simanungkalit; Rasti Saraswati; Irawan Irawan
Indonesian Journal of Agricultural Science Vol 8, No 1 (2007): April 2007
Publisher : Indonesian Agency for Agricultural Research and Development

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.21082/ijas.v8n1.2007.p31-38

Abstract

Biofertilizers currently sold in the market are not labeled with a distinct quality standard. As such, farmers may buy low quality biofertilizers, which can reduce their profit and trust on the benefit of biofertilizers. This paper presents the characteristics of various products of commercial biofertilizers as well as farmers’ knowledge and experience on the products. The study was carried out in 2004-2006 by collecting and analyzing data on registered commercial biofertilizers, checking their availability at the market (39 agricultural shops), and interviewing farmers on their knowledge and experience on the use of biofertilizers on various farming systems in Bandung District, West Java (86 respondents) and Semarang District, Central Java (77 respondents). The quality of biofertilizers was tested in the laboratory based on microbial density and its functional (phenotypic) traits. The study showed that amongst various brands of biofertilizers commercialized, 41 brands of them have been officially registered as commercial products. Two brands of other biofertilizers found in agricultural shops were registered as organic or inorganic fertilizers. In general, each biofertilizer contained two or more microbial strains and was claimed to have multiple functions. However, most of them (>90%) were not labeled with expiry date information. Macronutrient contents (NPK) of some microbial carriers were almost equal to those of organic fertilizers. Around 38% of respondents in Bandung knew biofertilizers and less than 10% have ever used them. In Semarang, however, familiarity and personal experience of the respondents were much lower, i.e. 10% and 3%, respectively. About 67% and 50% of agricultural shops in Bandung and Semarang sold biofertilizers, respectively. Laboratory analyses showed that microbial density of five biofertilizers tested was lower than that of product specification, although most of them were positive for N-fixing and P-solubilizing traits. Some microbial strains contained less than 103 cfu based on the dilution level testing. These figures imply the urgent need to improve the existing quality standard system of biofertilizers including its control mechanisms.