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The CYN degradation kinetics of each bacterial species were studied using High Performance Liquid Chromatography. The greatest CYN degradation (28.22 ± 0.24%) was shown by the bacterium B. cereus-S in 5.0 mg/L CYN within 14 days. The CYN degradation by the other strains was lower than 10% under the same conditions. Further studies employing different initial concentrations of CYN revealed that B. cereus-S could degrade lower CYN concentrations at a higher percentage (1.0 mg/L, 2.5 mg/L, and 5.0 mg/L of CYN removal percentages were 36.83 ± 2.43%, 32.25 ± 1.25%, and 24.72 ± 0.40%, respectively, after 14 days of incubation at 28℃ and pH 7). The maximum average degradation rates were recorded for 1.0 mg/L, 2.5 mg/L, and 5.0 mg/L CYN on the 6th (0.05 ± 0.00 mg/L/day), 8th (0.04 ± 0.01 mg/L/day), and 12th (0.02 ± 0.01 mg/L/day) days of incubation, respectively. The study showed the potentiality of the bacterium B. cereus-S on the application for degrading CYN among the tested bacteria species. [ABSTRACT FROM AUTHOR]

Rice (Oryza sativa L.) is the staple food in Sri Lanka and phosphorus (P) and potassium (K) are major nutrients for the rice plant. However, the variation of P and K contents (mg kg-1) in rice soils and rice grains as affected by agro-climatic zones (ACZs), water source used (i.e., major irrigation, minor irrigation and rain-fed) and cropping systems adopted (i.e., fallow, vegetable, perennials, other field crops) by Sri Lankan farmers are not well elucidated, and are thus investigated in the present study. A total of 200 rice soil and 230 rice grain samples across the country were collected from farmer fields, representing different ACZs, water sources used, and cropping systems adopted using a stratified random sampling approach. The total and available P and K contents in rice soil, and the P and K contents in rice grains were determined. The plant-available P contents in soil were similar among ACZs, water sources, and rice-based cropping systems. Exchangeable K content was higher in rice fields where vegetables were cultivated in the previous season. Grain P and K contents were similar among the water sources used and rice-based cropping systems. Grain P contents was the lowest in the Low country Wet zone. Soil available-P and total-P contents (r = 0.29, p < 0.0001), and grain P and K contents were positively correlated (r = 0.51, p < 0.0001). The knowledge generated in the present study is important in P and K nutrient management in rice cultivation in the country. [ABSTRACT FROM AUTHOR]

Various environmental, economic and health problems have arisen in the world due to the continuous application of N-fertilisers for crop production, especially in the third world countries. The current study was undertaken to develop effective rhizobial inoculants for three major legume crops in Sri Lanka, namely Vigna mungo, Vigna radiata and Glycine max to replace the application of nitrogen fertilisers. Rhizobial isolates were obtained from the root nodules of different cultivars of edible legumes, non-edible wild legumes and wild relatives of Vigna spp. Authentication and screening for effectiveness of the isolates were carried out, and five strains were selected as effective isolates and cross inoculated with the three legumes along with a stress tolerant strain, which was previously screened. A pot experiment was followed by a field trial in the dry zone of Sri Lanka under farmers' conditions as single and multi-strain inoculations. The results of the pot experiment indicated that the addition of rhizobial inoculants increased the growth performance in all treatments. In the field trial, both single and multi-strain inoculants gave significant increases in yield, compared to N-fertiliser application in all three crops, viz; an increase of the yield from 3 % to 39 % in V. mungo, 5 % to 14 % in V. radiata, and 4 % to 13 % in G. max. In conclusion, the current study has shown that single and multi-strain rhizobial inoculants are capable of completely replacing urea application to V. mungo, V. radiata and G. max, in Sri Lanka without any yield reduction. [ABSTRACT FROM AUTHOR]

Mineral detection using remote sensing techniques is important since it saves the time and effort of carrying out manual land surveys. In this paper a novel algorithm, which can be used to detect ilmenite using hyperspectral image analysis is discussed. To investigate this task, a hyperspectral image obtained from the Earth Observing-1 (EO-1) satellite's Hyperion sensor was used. In the proposed algorithm, first, principal component analysis (PCA) was used for dimensionality reduction and an Euclidean distancebased method was used to extract the pixels containing soil. Thereafter, lab spectral data of typical ilmenite deposits were considered as the reference and a correlation factor analysis was carried out to determine the soil pixels, which are most likely to contain ilmenite and most unlikely to contain ilmenite. Using these two sets of pixels, a training set was constructed to apply Fisher's discriminant analysis (FDA) in order to separate the dataset into two distinct classes - ilmenite and non-ilmenite. Based on the spectral similarity, each pixel of the image was classified under one of these classes. This paper also introduces a probability-based approach to obtain results that are more accurate. A probability density function was designed considering the spatial distribution of the mineral. Thereafter, classification was done considering the probability measure as well. Lab tests performed on the soil samples collected from the locations, which were detected by the algorithm validate that the algorithm is accurate. [ABSTRACT FROM AUTHOR]

Two fungal strains capable of decolourisation of CI Direct Blue 201 textile dye were isolated from textile wastewater effluent sites in Sri Lanka and they were identified as Aspergillus aculeatus and Aspergillus nomius using 18s rRNA analysis. A. nomius and A. aculeatus showed 98% decolourisation of CI Direct Blue 201 textile dye (50 mg/L) at 3rd day of incubation with the supplement of modified Kirk's medium. Both fungal strains were found to be more effective for dye decolourisation at temperatures ranging from 24 °C to 36 °C. Further, it was found that the decolourisation potential increased at pH 5 and 10 under shaking condition (100 rpm) with the presence of glucose and nitrate as additional carbon and nitrogen sources. Seed germination assay showed less germination (22.2 ± 5.0% and 10.0 ± 3.3% for Oryza sativa and Vigna radiata, respectively) when seeds were exposed to the original dye in comparison to 100% seed germination observed when exposed to fungal treated dye effluent, showing the detoxification of dye by the fungal isolates. [ABSTRACT FROM AUTHOR]

The objective of this study was to develop an environmental friendly, low cost technology for cultivation of livestock forage legumes so as to minimise the use of nitrogen fertiliser (N-fertiliser) that pollute the pristine highland watersheds. Inoculants were prepared by screening several rhizobial isolates obtained from farm cultivated clover plants and selecting the most efficient strain. In field tests at three separate sites, the average amount of biomass produced by inoculated Trifolium plants was higher compared with the plants fertilised with urea. Root nodulation and other plant parameters were assessed on several randomly harvested plants 60 days after planting. The results indicate that root nodulation and plant growth increased significantly in inoculated plants. Average results obtained from nine crop cuts taken during a period of 15 months showed that regeneration and biomass production after crop cutting were better under inoculation than under N-fertiliser application. It is inferred that rhizobial inoculation has the potential to replace N-fertiliser applications to Trifolium repens L. in the Sri Lankan highland farming systems. [ABSTRACT FROM AUTHOR]