Showing papers in "The South Pacific Journal of Natural Science in 2009"

Improving taro (Colocasia esculenta var. esculenta) production using biotechnological approaches

Abstract: Taro (Colocasia esculenta L. Schott) is an important crop worldwide but is of particular significance in many Pacific Island countries where it forms part of the staple diet and serves as an export commodity. Escalating pest and disease problems are jeopardizing taro production with serious implications to food security and trade. Biotechnological approaches to addressing pest and disease problems, such as somatic embryogenesis and transgenesis, are potentially viable options. However, despite biotechnological advancements in higher profile agronomic crops, such progress in relation to Colocasia esculenta var. esculenta has been slow. This paper reviews taro biology, highlights the cultural and economic significance of taro in Pacific Island countries and discusses the progress made towards the molecular breeding of this important crop to date.

Studies on biodegradation of crude oil by Aspergillus niger

Abstract: Hydrocarbon degrading microorganisms play a major r ole in the environment. In the present study crude oil degrading fungal strain Aspergillus niger was isolated from o il contaminated soil near crude oil production well (Lingala) Andhra Pradesh. The rate of reduction in some petroleum hy drocarbon fractions, such as n-alkanes, aromatics, nitrogen, sulfur and oxygen (NSO)-containing compounds and polycycli c aromatic hydrocarbons (PAHs), were monitored by m eans of gas chromatography. The nC 17/Pristine and n C18/Phytane ratios, extrapolated from the GC profiles decreased from the initial value of 2.510 and 7.289 to 0.132 and 0.474 respect ively at day 60.

Microbial degradation of polyethylene (PE)

Abstract: Thirty two bacterial isolates were obtained from soil by soil burial method followed by enrichment culture technique in film culturing (FC) media. Bacterial isolates differing in morphology were selected, purified and maintained at 4°C. Thirty % of these isolates were found to be Gram negative and 50% showed positive starch hydrolysis test and were screened for their ability to degrade Low Density Polyethylene (untreated, UV and heat strips) in film culturing media and percent weight loss of polyethylene after 4th week was determined. Among various isolates, highest degradation was by Is 3, Is 22 and Is 31 to the range of 25–27%, of UV treated polyethylene strips. High temperature (40°C), was found to enhance degradation rate of polyethylene more effectively by 24–28% compared to low temperature at 30°C (18–21%). Degradation of treated polyethylene strips (UV, heat steam) was up to 4% by compost treatment as studied by using CO2 evolution, an estimation tool to analyze % degradation. Bacterial activity was also affected by various environmental factors like sunlight, temperature, oxygen etc.

Gene effects for different metric traits under normal and high temperature stress environments in wheat (T. aestivum L. Em Thell)

Abstract: The present investigation was conducted to analyze gene effects for grain yield and its components under two different environments. Nine wheat genotypes were selected to generate the experimental material comprised six parental and segregating generations (P1, P2, F1, F2, BC1 and BS1 of BC1 of each of the following six crosses – PBW 343 x WH 283, PBW 343 x WH 542, PBW 343 x PBW 435, UP 2565 x UP 2425, EIGN 1 x Raj 3765 and EIGN 8 x UP 2425. Joint scaling tests revealed the presence of epitasis. Six parameter model revealed the significance of additive gene effects (d) for biological and grain yield and their components in most of the crosses. The relative magnitude of (h) was higher than (d) in all the crosses for most of the characters while additive x additive (i) effects appeared to be significant for grain yield per plant (E1) and number of grain per spike (E2) in PBW 343 x WH 283. Significant (i) type of interaction was recorded in PBW 343 x WH 542 for number of grain per spike (E1), number of tillers per plant (E2) in PBW 343 x PBW 435 and for 1000-grain weight in UP 2565 x UP 2425. Pedigree method and simple selection in crosses like PBW 343 x PBW 435, UP 2565 x UP 2425, PBW 343 x WH 283 and PBW 343 x WH 542 should be used for improvement of traits governed by additive and additive x additive gene effect.

RAPD analysis for genetic polymorphism in bread wheat (Triticum aestivum L. Em Thell) genotypes varying for grain protein content

Abstract: Genetic polymorphism was investigated among nine s pring wheat genotypes, differing in grain protein c ontent, including C-306M10 ( mutant of drought tolerant va riety C306), DI 8, DI 9, DI 16, DI 20, DI 716, DI 7 17, DI 728 (near isogenic lines) and HGPC (from Wheat x R ye crosses) using 55 RAPD primers. Out of 55 primer s used, only 36 amplified and generated 2(OPG08, OP D0 5) and 12 (OPD02 ) bands. A total of 342 amplified p were observed, of which 168 were polymorphic (49.12 %) while 174 were monomorphic. The primer OPC-05 aOPC-07 revealed 92.86% and 80.00% polymorphism, respectively and t hese primers were most useful in characterization o f nine wheat genotypes included in this study. The primer OPG-08 showed no polymorphism. It is concluded that the primers OPC -05 and OPC-07 were very effective in distinguishing wheat genotypes in the present study. Twenty six RAPD primers produced a t otal of 48 unique bands for high protein content that were either present o r absent in HGPC a-high grain protein genotype and thus can be used in wheat improvement through marker-assisted select ion (for the bands which are unique by their presen ce). Data (RAPD analysis) were used to generate the similarit y coefficients using ‘siMqual’ subprogram of softwa re NTSYS-PC. The similarity coefficient values ranged from 0.97(DI8 and DI9) to 0.68 (DI9 and HGPC), indicating high genetic variability among the selected wheat genotypes. The cluster analysis and principle component analysis broadly divided the wheat genotypes into two groups and sho wed that DI 9 and HGPC were most divergent genotype s.

The annual effective dose due to natural radionuclides in the reservoir and tap water in Yaoundé area, Cameroon

Abstract: The average concentrations of radionuclides of reservoir and tap water in the Yaounde area, with a population of 1.5 million inhabitants were estimated from measurements of mean specific activity using a well calibrated Canberra NaI(Tl) detector system. Water samples were collected from reservoirs and taps during the dry and the rainy seasons respectively in December 2002 and July 2003. The radionuclides observed with regularity belonged to the decay series naturally occurring radionuclides headed by 238U and 232Th as well as the non-series nuclide 40K. The average specific activity values obtained for 40K, 226Ra and 228Ra, respectively were for reservoir water 70 ± 11 BqL–1; 8.7 ± 3.5 BqL–1; 0.6 ± 0.2 BqL–1 during the dry season, and 50 ± 9 BqL–1; 8.5 ± 3.7 BqL–1; 0.6 ± 0.2 BqL–1 during the rainy season and for tap water, we have respectively 111 ± 17 BqL–1; 11.4 ± 3.7 BqL–1; 1 ± 0.3 BqL–1 during the dry season, and 51 ± 10 BqL–1; 9 ± 3.5 BqL–1; 0.7 ± 0.2 BqL–1 during the rainy season. The annual effective dose received by Yaounde adult population as a result of ingestion of this drinking water is respectively 0.925 mSv for the reservoir water and 1.052 mSv for the tap water.

Morphological variation, an expanded description and ethnobotanical evaluation of Cycas seemannii A.Braun (Cycadaceae)

Abstract: Cycas seemannii (Cycadaceae) is a widespread and highly variable species. This study investigates morphological variability and ethnobotanical uses throughout the entire range (Torres Strait Islands, Vanuatu, New Caledonia, Fiji and Tonga) of the species. The morphological characters studied are highly variable among populations and unrelated to genetic differences. Characters are also more variable than previously assumed and because of this we provide an updated, detailed taxonomic description of Cycas seemannii based on extensive morphometric data, fieldwork and herbarium specimens. The plant is of great cultural importance in Vanuatu, its seeds are utilised as a source of starch and it is a widely cultivated ornamental. Possible consequences of the plant's decreasing cultural importance are discussed.

Effects of Nickel Salt Concentrations on Germination and Development of Grevillea exul var. rubiginosa

Abstract: Endemic plant species have been considered as one of the best means of ecological restoration of exploited mine sites in New Caledonia. These plants have the adaptability characteristics that allow them to thrive on serpentine soils. This study has investigated the physiological effects of nickel concentrations at different developmental stages on Grevillea exul var. rubiginosa an endemic New Caledonian species. The first two stages of a plant life cycle germination and post germination under controlled conditions were studied. The experiment involved Petri dish germination and growth of seeds and seedlings respectively particularly root development and length in different salts of nickel (acetate, chloride and sulphate) with 0­500 ppm concentrations. Decrease in both studied parameters: germination rates and root lengths were observed with increasing concentrations of nickel solutions supplied to seeds. A minimum concentration of 5 ppm of nickel in the medium had a positive effect on germination rate as well as root length. Results suggest that it is the concentration of nickel used in the present investigation to test the germination rate and root elongation in Grevillea exul var. rubiginosa which are essential for experimental work in the field rather than the form (salt) of nickel. These results will be help-full in re-vegetation efforts of nickel mining sites in New Caledonia.

Effect of hybrids, plant density and fertility levels on nutrient concentration, uptake and productivity of pearl millet in semi arid environment.

Abstract: A Field experiment was conducted at Crop Research F arm, Chaudhary Charan Singh Haryana Agricultural Un iversity, Hisar, during the kharif seasons of 2004 and 2005 to find out sui table spacing for pearl millet hybrids along with N and P levels so as to increase the productivity of pearl millet. The experiment was la id out in split plot design allocating combinations of two hybrids and three plant densities in main plots and four fertility levels iplots with three replications. Highest pooled grain yield was recorded by HHB 672. Sowing pearl millet at 45x12 cm spacing produced highest pooled grain and stover yield. Application of 90 kg N + 45 kg P2O5 ha -1 resulted maximum pooled grain and stover yield and was at par with 60 kg N + 30 kg P 2O5 ha -1 . HHB 67-2 had significantly higher total uptake over HHB 67. Wider spacing of 60x12 cm had higher NPK content but 45x12 cm resulted into higher total uptake of NPK. NPK content and uptake was found higher when pearl millet was fertilized with 90 kg N + 45 kg P 2O5 ha -1 .

Trace element concentrations in sediments from Kadavu passage, Fiji

Abstract: Grab sediments, collected from 11 locations from the Pacific Ocean floor in the region between Suva Peninsula and Kadavu Island, Fiji, were investigated for concentrations of 20 elements using neutron activation and high-resolution gamma ray spectroscopy techniques. The sediments were collected at distances between 5-35 km from the mainland and at ocean depths ranging from 500 to 2000 m. A comparison of the elemental abundances of these sediments with those of the Suva lagoon and other nearby locations indicates that the ocean sediments are likely to be derived from sediments washed out to sea from the mainland. The sediments also show no evidence of any metal contamination from the industrial activity in the Suva metropolitan area.

Composition and structure of the cloud forest on Mt. Delaco, Gau, Fiji

Abstract: The composition and structure of cloud forest on Mt. Delaco (715m), Gau, Fiji Islands, is investigated using a transect following a ridge. Diameter (dbh), height, epiphyte cover and distance to the nearest neighbour were measured for each plant of 5 or more cm in dbh. A total of 42 vascular species were identified. The canopy was 3-5m tall, with Alpinia boia reaching 7m in height. The tree fern Dicksonia brackenridgei dominated the vegetation, accounting for 56% of the total basal area. Rapanea myricifolia, Hedycarya dorstenoides and Ascarina diffusa were other common species. Epiphytes were abundant and epiphyte cover for most trees was more than 50%. The most common epiphytes were Nephrolepis tuberosa and Nephrolepis saligna, Collospermum montanum, Peperomia spp., mosses and filmy ferns (Hymenophyllaceae) were other common species. A species of Freycinetia was the dominant climber. There was a moderately strong correlation between epiphyte richness and dbh of the host species (r = 0.59). The limited literature on cloud forest in the tropical insular Pacific suggests that while many taxa are shared, the species composition may vary considerably on different mountains.

Maximization of poly-β-hydroxy butyrate production by rhizo-bacteria using eco-friendly agri-byproducts

Abstract: Attempts have been made, using rhizobacteria, to de velop a protocol for economical polyhydroxybutyrate production using agribyproducts. The optimum conditions for maximum PHB production were found with modified glucose minimal media. A cost effective media using exclusively readily available agri-bypr oducts yielding as much as 60 mg/l PHB (which corre spond to 53.1 % of the biomass) from isolates of rhizobacteria has been de veloped