Browsing by Author "Aluwihare, Y.C."

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    Quantitative Assessment of Leaf Color Change in Response to Phosphate Deficiency Tolerance in Rice
    (Uva Wellassa University of Sri Lanka, 2013) Aluwihare, Y.C.; Lelwala, R.; Ishan, M.; Sooriyapathirana, S.D.S.S.; Sirisena, D.N.; Samarasinghe, W.L.G.
    Phosphate deficiency tolerance (PDT) is one of the important traits in improving rice varieties. Annual expenditure on phosphate fertilizers for rice is Rs.1158.4 millions in Sri Lanka. Application of phosphate fertilizers also causes many other environmental and health problems (Wickramasinghe et al., 2009). If PDT rice varieties can be developed, they can be grown with reduced fertilizer applications, higher profit margin, and minimum negative effects of phosphate applications (Wissua and Ae, 2001). Because of the phosphate deficiency, the leaf color is changed. If the color differences in leaves can be quantitatively measured, it can be used to assess the PDT of different rice varieties (Fageria et al., 1988). The present study was conducted to screen selected traditional and improved rice varieties developed by Rice Research and Development Institute (RRDI), Batalagoda (Bg) for PDT using the leaf color change measurements in a quantitative approach. Methodology A total of 10 rice genotypes (nine varieties: Bg 358, H 10, H4, Bg 360, Bg 403, Bg 379-2, Bg 352, H 7 and MAS and the landrace: Suduheenati) were grown in a field at RRDI, Bathalagoda where no fertilizer has been applied for last 30 years. Plants were maintained with standard management practices except no phosphate application. The leaf color measurements; L*, a* and b* were recorded in four replicates per plant on the sixth week after planting using a spectrophotometer (CR-10, Konika Minolta, Tokyo, Japan). L* measured the darkness/lightness range of the visual color from black (-L*) to white (+L*), a* measured the range from green (-a*) to red (+a*) while b* measured the range from blue (-b*) to yellow (+b*). The quantitative estimates, C* (chroma; estimate of dullness/sharpness of the visual color) and H* (hue angle; estimate of the overall visual color) were calculated using the following equations (Melgosa, 2000).
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    Study the Mitochondrial COI Gene Sequence Variation of Two Isolated Populations of Cephalopholis sonnerati (Valenciennes, 1828) in East and West Coasts of Sri Lanka
    (Uva Wellassa University of Sri Lanka, 2019) Jayawardane, I.D.S.S.; Aluwihare, Y.C.; Dalpathadu, K.R.; Haputhantri, H.S.S.K.; Athula, J.A.
    Cephalopholis sonnerati (Thambuwa) remained as one of the main reef fish species in the marine fishery sector in Sri Lanka. The major problem associated with the fish species is the huge population reduction in last few years due to the overexploitation. At present, this species has been protected under the fisheries law and this decision has been taken as a precautionary conservation and management measure. It is essential to conduct fish stock studies to assessment of sustainable fishing levels based on stocks. C. sonnerati in East and West coast may be from two different fish stocks due to the limited breeding between the populations. Due to the restriction of gene flow between two isolated populations, nucleotide level variation would provide a basic idea about population and stock structure. The study was conducted with the aim of identification of genetic variation at the mitochondrial cytochrome oxidase subunit I (COI) gene in two isolated populations. Fish samples were collected from east coast (Ampara and Batticaloa) and west coast (Chilaw). DNA was extracted by using CTAB method. PCR reaction was performed by using primers designed by COI gene sequences. PCR amplified products were sequenced and sequences were analyzed using BLASTn at NCBI and were aligned by using BioEdit and ClustalW sequence alignment tools. Even though the COI region is highly conserved region, single nucleotide polymorphism (SNP) was identified at 336th position (T/C) in both west and east coast C. sonnerati samples. To confirm the SNP in COI region more samples need to be used in the future studies. Due to the conserved nature of COI region very low nucleotide level difference was observed and all individuals shared similar sequences pattern. It can be confirmed that the two populations may still from the same stock. To confirm that it can be used microsatellite markers along with SNPs in future. This study provides a basic for future genetic stock studies.