In 2011, we found a new bacterial disease characterized by wilt, dwarf and blight symptoms on sweet corn in Batu, East Java, Indonesia. The objective of this study is to characterize the causal agent of the disease. In this study, several assays were conducted, including hypersensitive response, pathogenicity, physiological and biochemical characteristics, PCR detection using two specific species primer pairs for Pantoea stewartii pv. stewartii, and homology analysis of 16S rRNA gene sequence. Four Gram-negative, non-motile, facultative anaerobic bacteria were isolated from the diseased tissue. Only two strains, BD1 and BB2, gave positive result in hypersensitive reaction, pathogenicity, and Koch's postulate assays. BB2 and BD1 strains also showed positive results in the PCR amplification using specific primers derived from the P. stewartii subsp. stewartii 16-23S gene region but showed negative result when using primers derived from P. stewartii subsp. stewartii hrpS gene region. Sequence of partial 16S rRNA gene of BD1 and BB2 showed highest homology at 96% to P. stewartii subsp. stewartii strain ATCC 8199 (NR. 044800.1). This results suggest that bacterial pathogens isolated from sweet corn in Batu were strains of Pantoea spp.

Tomato is an important horticultural commodity in Indonesia and plays strategic role in fulfilling daily needs of the public. The increase in production of tomato can be done by optimizing the provision of nutrients that support growth. The ability of bacteria as biological fertilizer to dissolve phosphate and produce IAA (Indole Acetic Acid) are important criteria for the use of bacteria as agents of plant growth promoters. The purpose of this study was to determine the ability of some isolates of Bacillus subtilis and Pseudomonas fluorescens in dissolving phosphate and produce IAA to enhance the growth of tomato. Phosphate test results showed that all isolates of B. subtilis and P. fluorescens capable of dissolving phosphate with the highest value indicated by P. fluorescens UB-PF5 (18 mm). All isolates of bacteria capable to produce IAA. The resulting value IAA ranged from 0.69 to 1.09 ppm with the highest value produced by B. subtilis UB-ABS2 (1.09 ppm). The test results on the parameters of root weight, root length, plant height and number of leaves showed that tomato treated with B. subtilis and P. fluorescens increased significant growth compared with watering only with distilled water. The highest increased root weight and root length were resulted by P. fluorescens UB-PF5 with values 97.10% and 64.83%, respectively. The highest increased plant height and number of leaves length were resulted by P. fluorescens UB-PF6 with values 38,80% and 30,7%, respectively.

Abstract. Astriani M, Zubaidah S, Abadi AL, Suarsini E. 2020. Pseudomonas plecoglossicida as a novel bacterium for phosphate solubilizing and indole-3-acetic acid-producing from soybean rhizospheric soils of East Java, Indonesia. Biodiversitas 21: 578-586. The use of synthetic fertilizers to grow soybean (Glycine max (L.) Merrill) in a long time, can increase the risk of environmental damage. Therefore, the current study aimed to find phosphate solubilizing bacteria that can produce indole-3-acetic acid (IAA) hormone to minimize the use of chemical fertilizers. Superior isolates selected through characterization of phosphate solubilization activity on Pikovskaya medium, screening of IAA producing bacteria, quantitative estimation of phosphate solubilizing activity using a spectrophotometer, hypersensitivity assay, antagonist within isolate assay, and molecular identification of selected bacterial isolates using 16S rRNA sequencing with primer forward 63f and primer reverse 1387r. Among the isolated bacteria, isolate Arj8 showed the highest phosphate solubilizing activity and IAA production. Molecular identification indicated that isolate Arj8 shared 100% similarity with Pseudomonas plecoglossicida. The highest phosphate solubilizing activity (75.39 mg/L) and IAA production (38.89 ppm) recorded on day-3. Multiple potentialities of P. plecoglossicida as phosphate solubilizing and IAA producing bacterium are a novel finding in the development of bioinoculants as bio-fertilizers that can reduce dependency on synthetic chemical fertilizers.

The Research was aimed to identify the diversity of arthropods in Cocoa plantation in three strata of shade tree. Research was conducted in Rahmat village, the sub-district of Palolo, District of Sigi, the Province of Central Sulawesi, Indonesia from December 2012 to June 2013.Berlese funnel, Pitfall, Malaise and Light trap were used to collect arthropod samples. There were five indices such as species richness (R), species evenness (E), species diversity (H`and D), and species similarity (Iss) to analyze the diversity of arthropods in cocoa plantations. The result showed that species richness (R) of arthropods under the two strata of shade tree, species evenness (E) and both of species diversity indices, Shannon (H`) and Simpson (D) was the highest, with value of 18.216, 0.839, 4.383, and 0.833 respectively. In addition, percentage of species similarity (Iss) was the highest under two strata of shade tree with value 72.297%.

<p><span>Jatropha is a plant that has many functions, but this plant can be attacked by various diseases. Expert systems can be applied in identifying so that can help both farmers and extension workers to identify the disease. one of method that can be used is Extreme Learning Machine. Extreme Learning Machine is a method of learning in Neural Network which has a one-time iteration concept in each process. In this study get a maximum accuracy of 66.67% with an average accuracy of 60.61%. This proves the identification using Extreme Learning Machine is better than the comparison method that has been done before.</span></p>

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This study was to determine the fruit maturity level of wild bitter gourd and the composition of water extract which is effective as antifeedant and appropriate for mortality test on armyworm larvae. Results obtained show that water extract of wild bitter gourd fruit contains phenolic compounds, flavonoids and triterpenoids. Terpenoid compounds contained in water extract of fruits at maturity level 4H, 8H and 12H were momordicoside L, momordicoside K, compound 3β, β7, 25-trihydroxycucurbita-5.23(E)-diena-19-al:R1=H, R2= H and momordicine 1. Fruit maturity level 4H 50% and 4H 60% resulted to the highest antifeedant index, ie 40.08% and 44.20%. LC 50 at fruit maturity level 4H observed on day 7 was 40%.