BIOTROPIA - The Southeast Asian Journal of Tropical Biology
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CONTROL OF AFLATOXIGENIC Aspergillus flavus IN PEANUTS USING NONAFLATOXIGENIC A. flavus, A. niger and Trichoderma harzianum
Get PDFThe effects of nontoxigenic Aspergillus flavus, A. niger and Trichoderma harzianum inoculated into planting media on toxigenic A. flavus infection and its aflatoxin production in peanut kernels at harvest were investigated together with (1) the moisture content of planting media before peanut planting, at the time of inflorescence, and at harvest, (2) the population of aflatoxigenic and nonaflatoxigenic A. flavus, A. niger and T. harzianum in peanut planting media before peanut planting, at the time of inflorescence, and at harvest, (3) the moisture content of peanut kernels at harvest, and (4) toxigenic A. flavus invasion in peanut plant parts (roots, stems, petioles, leaves and flowers) at the time of inflorescence. The fungal isolates were inoculated into planting media at the same time with the planting of peanut seeds. Peanut plants were grown under glasshouse conditions. Treated planting media were inoculated with the combined use of (1) toxigenic and nontoxigenic A. flavus, (2) toxigenic A. flavus and A. niger, and (3) toxigenic A. flavus and T. harzianum. Planting media inoculated only with each fungal isolate and uninoculated planting media were used as controls. Two watering treatments of peanut plants were carried out, i.e. watering until harvest and not watering for 15 days before harvest. The populations of the fungal isolates in the planting media and peanut kernels were determined using dilution method followed by pour plate method; the percentages of toxigenic A. flavus and test fungal colonizations in peanut plant parts were determined using plating method; the moisture content of planting media and peanut kernels were determined using oven method; the aflatoxin content of peanut kernels was determined using Thin Layer Chromatography method. The results indicated that at the time of harvest the decrease in moisture contents of planting media not watered for 15 days before harvest was higher than those watered until harvest. The lowest population of toxigenic A. flavus was in planting media inoculated with the combined use of toxigenic and nontoxigenic A. flavus at the time of inflorescence and at the time of harvest. Toxigenic A. flavus could invade the roots, stems and flowers of peanut plants. The lowest percentage of invasion was on the plant parts which planting media were inoculated with the combined use of toxigenic and nontoxigenic A. flavus. The moisture content of peanut kernels originated from watered plants until harvest were higher than those not watered for 15 days before harvest. The population of toxigenic A. flavus in peanut kernels derived from the plants whose planting media were inoculated with the combined use of toxigenic A. flavus and each test fungi, was lower than those inoculated only with toxigenic A. flavus. It indicated that the test fungi inoculated into planting media could inhibit toxigenic A. flavus infection in peanut kernels. Aflatoxin was only detected in peanut kernels originated from one plant whose planting medium was inoculated only with toxigenic A. flavus and the plant was watered until the time of harvest. Toxigenic A. flavus infection and aflatoxin production were not influenced by planting media which were not watered for 15 days before harvest. Keywords: Biocontrol / Aflatoxigenic / Nonaflatoxigenic / Aspergillus flavus I Aspergillus niger I Trichoderma harzianum I Peanut
ANALYSIS OF THE TEMPERATURE DEPENDENCE OF CO2 ASSIMILATION RATE (STUDY CASE: GLYCINE MAXL. MERR)
Get PDFThe maximum rate of carboxylation (Kcmax) and maximum rate of regeneration of Ribulose bisphosphate (RuBP) (controlled by the rate of electron transport, Jmax) arc two processes governing the photosynthetic capacity of plants. Both processes are affected by temperature. This paper examines how the response of these two photosynthetic capacities to temperature determines the temperature response curve of the CO2-assimilation rate for plants grown at different temperatures, by using the concept of the Farquhar €3 photosynthesis model. The goal is to use photosynthetic parameters from CO2 and light curves to predict the temperature dependence of the CO2-assimilation rate (A) of soybean and to estimate the preferred growth temperature. Analysis shows that the optimum temperature of the assimilation rate changes with the changing temperature dependence of carboxylation and regeneration of RuBP. Key words : temperature dependence/soybean/modeling photosynthesis/preferred growth temperature
HETEROLOGOUS EXPRESSION OF A CHITINASE GENE FROM AEROMONAS CAVIAEIN PSEUDOMONAS FLUORESCENS
Get PDFA transcriptional fusion for an Aeromonas caviae chitinase gene was constructed under the control of a constitutive promoter of the kanaraycin resistance gene (PKmR). The construct was inserted into a medium copy number broad host range plasmid vector to yield recombinant plasmid pAM340, which harbored transcriptional fusion PKmR- chi. Another transcriptional fusion, Ptac-chi, in a recombinant plasmid pAM630, was conducted as comparison. Triparental mating of E. coli carrying the recombinant plasmids with Pseudomotws fluorescens 5100, a phyllosphere bacterium, was performed. Pseudomonas fluorescens 5100 exconjugants were examined for constitutive expression of chitinase employing a spectrophotometric assay; they showed stronger chitin degradation activity than Escherichia coli transformants. Using a fungal antagonism plate assay, this chitinolytic P. fluorescens, however, could not inhibit selected phytopathogenic fungi. Keywords:   Aeromonas  caviae/ chitinase  gene/transcriptional  fusion/PKm\u27V  Vtac-chilPseudomonas fluorescen
EFFECT OF PHYTASE SUPPLEMENTATION IN SOYBEAN MEAL BASED DIET ON NUTRIENT DIGESTIBILITY AND GROWTH PERFORMANCE OF GREEN CATFISH (Hemibagrus nemurus)
Get PDFThis experiment was conducted to evaluate the effect of phytase supplemented to the diet on phosphorus (P) digestibility and growth performance of the green catfish Hemibagrus nemurus. Five kinds of experimental diets were used in this experiment, namely diets A, B, C, D and E. Diet A, as a control, was supplemented with inorganic P, without phytase supplementation. Diet B, C, D and E were supplemented with 0, 20, 40 and 60 mg phytase/100 g soybean meal (SBM), respectively, without inorganic P supplementation. Fifteen fish with initial body weight of 6.9 + 0.2 g were stocked into each 60-l aquarium. Fish were fed on the diets for 60 days. Results indicated that P digestibility increased from 64.5% to 87.0% as phytase supplement increased from 0 mg in diet B to 60 mg phytase/100 g SBM in diet E. P digestibility in diet E was higher than that in diet A (77.6%). The daily growth rate and feed conversion ratio followed similar trend. P, Calcium (Ca) and Zinc (Zn) concentration in the whole body and bone of fish fed diet E were higher than the fish fed diet B, C and D, but were insignificant compared to the fish fed diet A. Nitrogen (N) and P loading by fish fed diet E were, respectively, 76% and 20% lower than those in fish fed the control diet. It is concluded that the inclusion of 60 mg phytase/100 g SBM in the diet of the green catfish could replace the utilization of inorganic P increase the digestibility of the diet thereby resulting in increased growth rate and reduced excretion of P and N into the waters.
Keywords: Hemibagrus nemurus, phytase, soybean meal, phosphorus
PRODUCTION STRUCTURE OF MAIN COMMERCIAL TREE SPECIES IN A MANGROVE FOREST IN EAST SUMATERA, INDONESIA
Get PDFProduction structure of main commercial tree species was studied in a mangrove forest in East Sumatera, Indonesia. This research was carried out in January 1991 using the estimation of standing biomass with stratified clipping method in order to know the production structure of the main commercial tree species in this mangrove forest, i.e. Rhizophora apiculata, Bruguieraparviflora and B. sexangula. The results obtained show that R. apiculata tended to have a sparser foliage of thicker leaves along the stem than B. parviflora or B. sexangula; therefore, R. apiculata is regarded as a shade-intolerant tree species. In contrast, either B. parviflora or B. sexangula tended to have a larger proportion of leaves and branches along the stem; consequently, those species are recognized as shade-tolerant tree species
STUDIES ON THE BREEDING STRUCTURE OF TREE SPECIES IN THE TROPICAL RAIN FOREST. I: FAMILY CLUMPS AND INTRAPOPULATION DIFFERENTIATION
Get PDFBreeding structures of two tropical rain forest tree species, Altingia excelsa in Java and Agathis borneensis in Kalimantan were investigated. Assuming that similarity in the assortment pattern of the isoperoxidase bands tells genetic relationship between trees, on the one hand, and that inbreeding increases smaller values of the disagreement counts, on the other, it has been concluded that inbreeding occurs considerably in Altingia excelsa and to some extent in Agathis borneensis. Finding that trees showing very low disagreement counts are located close to each other, they were grouped as an assumptive family. It was found that different families were quite dissimilar with respect to isoperoxide constitution and in several leaf characters as well. The distance between two trees at which they can mate is estimated to be 16 to 18 meters or 16.5 meters and the area one family occupies is 200 to 250 m^, assuming that a family clump can be a breeding unit in Altingia excelsa, within which trees mate at random. Some families were distributed mixed with each other within the mating distance, but they were found still genetically differentiated from each other. This reproductive isolation among families is interpreted to be due to genetic differences between families in flowering time. In Agathis borneensis, there was no indication of family clump formation. Related trees may have been widely scattered in the forest, and the inbreeding of the species may be due to self-fertilization of individual trees and not to outcrossing between relatives
STRAIN DIFFERENCES IN TWO SPECIES OF CALLOSOBRUCHUS (COLEOPTERA: BRUCHIDAE) DEVELOPING ON SEEDS OF COWPEA {VIGNA UNGUICULATA (L.)} AND GREEN GRAM {V. RADIATA (L.)}
Get PDFOvipositional behaviour, development period, and density effect on adult survival of C. maculatus strains from Indonesia, Nigeria, and Yemen, and C. chinensis strains from Indonesia and Kenya on cowpea and green gram were studied at 20°C and 70% relative humidity. Variations on ovipositional behaviour were found among C. maculatus as well as among C. chinensis strains. Variations on developmental period were found only among C. maculatus strains. The developmental period of Callosobruchus spp. was shorter on green gram than that on cowpea. Density effect was remarkably found only on adult survival of C. maculatus Yemen strain. These results make useful contribution to the species biology, and have important implication if strains of these species are accidentally imported to countries, or when new legume crops are introduced
INDUCTION OF CALLUS FORMATION FROM DIFFERENT PARTS OF Citrus grandis (OSBECK) FLOWERS
Get PDF           The objectives of the present work were to study the capability of pomelo’s floral tissues to produce callus and to investigate the influence of plant growth regulators on callus induction and development. Various parts of flower namely petal, sepal, style, ovary, pistil and cup base were cultured onto Murashige and Skoog (MS) basal medium supplemented with different level of 2,4-dichlorophenoxyacetic acid (2,4-D), 6-benzylaminopurine (BAP) and 6-Furfurylaminopurine (kinetin). It was found that different part of flowers favored different level of hormone for callus induction. The highest formation of callus were obtained from petal and sepal cultured on MS media supplemented with 1.5 mg/l kinetin. For the style and pistil, 50 ± 2.3% of the explants had developed callus when cultured on MS media supplemented with 0.05 mg/l and 0.10 mg/l BAP respectively. On the other hand, sucrose agar (SA) media alone had managed to induce callus formation from almost every part of the flowers with a success rate between 7.69 ± 0.32 to 50 ± 3.18%. Callus formation was preferred from the uncut part of flowers as shown in the study on petal with percentage of formation was 14.6 ± 0.35%
GENETIC VARIABILITY OF POLYMESODA EROSA POPULATION IN THE SEGARA ANAKAN CILACAP
Get PDFAbstract Mud clams Polymesoda erosa in the Segara Anakan Cilacap are highly exploited by the local communities for daily consumption. This is presumed causing population decline and potentially causing loss of genetic diversity. Genetic diversity level within population can be obtained by population genetic study using molecular marker such as randomly amplified polymorphic DNA (RAPD). Here we amplified RAPD marker using ten arbitrary primers to assess genetic diversity of P. erosa population in the Segara Anakan Cilacap to provide genetic data for its sustainable use. The result proved that the used RAPD marker has high polymorphisms. The mud clam population was also showed a high level of heterozigosity and genetic diversity. This has important implication for the management plan towards ustainable use of P. erosa in the Segara Anakan Cilacap.  Key words: mud clam, RAPD, polymorphism, genetic diversit
PHYLOGENETIC ASSESSMENT OF GIANT CLAMS (TRIDACNIDAE) USING PARTIAL AMINO ACIDS SEQUENCES OF CYTOCHROME C OXIDASE I GENE
No full textPhylogenetic assessment of the giant clams need to be improved using various genetic markers since their relaionships are plagued by inconsistency result of several studies. This is especially true for the species under sub-genus Chametrachea. Here we studied the phylogeny of the giant clams using amino acid sequence of the mitochondrial COI gene. This study is aimed to assess and better understand the relationships of the giant clams, especially for three species under subgenus Chametrachea. The result showed close proximity between T. crocea and T. squamosa and between T. maxima and T. gigas. However, amino acids sequences of cytochrome c oxidase I gene was not strong enough to discriminate between T. crocea and T. squamosa. The majority of mutations were hydrophobic to hydrophilic amino acids