PGIS Research Congress

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Browsing PGIS Research Congress by Author "Abeysundara, H. T. K."

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    Plant diversity in organic and conventional rice farming: a case study from Malsiripura, Kurunegala District, Sri Lanka
    (Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Premachandra, M. V. N.; Madawala, H. M. S. P.; Nanayakkara, B. S.; Abeysundara, H. T. K.; Boyagoda, S. H.; Gunaratne, A. M. T. A.
    Use of chemical fertilizers in conventional farming contributes significantly to many environmental issues including biodiversity loss, whereas organic farming practices enhance agro-biodiversity by promoting a healthier ecosystem and enhanced ecosystem services. This study investigates the effects of organic (using organic fertilizer and other organic methods) and conventional farming (using chemical fertilizer, weedicides, pesticides and other conventional methods) on plant diversity in selected paddy fields in the intermediate climatic zone of Sri Lanka, during “Maha season”. Vegetation sampling was conducted in rice fields (representing 12 quadrats per field, inside fields and along field bunds), covering three growth phases of rice: vegetative (V), flowering (F), and ripening (R) using pin frame method. During V, F, and R stages, the organic paddy recorded a total plant abundance of 730, 1322, and 986 individuals, while conventional paddy recorded 429, 874, and 1349 individuals, respectively. Nearly 42%, 46% and 4% in organic paddy and 43%, 43% and 7% in conventional paddy were of native, exotic and endemic plant species, respectively. Although 100% of plants belonged to weeds in conventional paddy, only 80% of plants in organic paddy were weeds. The species richness was 13, 15, 15 in organic paddy and 7, 9 and 6 in conventional paddy for V, F and R stages, respectively. Shannon-Wiener diversity indices were 0.44 ± 0.55, 0.68 ± 0.40 and 0.31 ± 0.42 in organic paddy, 0.35 ± 0.36, 0.57 ± 0.41 and 0.44 ± 0.49 in conventional paddy, for the three phases, respectively. Species richness was significantly higher in organic than conventional farming in all phenophases. However, Shannon-Weiner Diversity Indices did not significantly vary among conventional and organic fields for the Maha season. Conventional farming had greater evenness in all three phases (V = 0.178, F = 0.261, R = 0.191) than organic farming (V = 0.171, F = 0.258, R = 0.103). The highest value of Simpsons’ Diversity index was reported in organic farming at F phase (5.07) followed by V (4.50) and R (3.45), and in conventional farming, the highest was recorded for R (3.77), followed by F (3.75) and V (2.72). Cyperus rotundus was the most abundant species (excluding O. sativa) in both paddy fields during all phenophases. The study underscores that while farming practices influence plant species richness, they do not significantly impact plant diversity.
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    Survival analysis of ovarian cancer patients and influential socio-demographic and genetic factors
    (Postgraduate Institute of Science (PGIS), University of Peradeniya, Sri Lanka, 2024-11-01) Neelawansha, S. L. S. F.; Abeysundara, H. T. K.; Dhanapala, C.; Wijeratne, A.
    Ovarian cancer is a fatal disease primarily affecting postmenopausal women, with the highest incidence in those over 50. Annually, approximately 190,000 new cases are diagnosed worldwide. Due to nonspecific symptoms and inadequate screening methods, the disease is often detected at advanced stages, leading to poor survival outcomes. Although less common than breast cancer, ovarian cancer-related deaths are projected to rise by 2040. This study aimed to estimate the survival probabilities of patients and assess how socio-demographic and genetic factors influence survival. Key socio-demographic variables include age at diagnosis (under 50, 51–70, and over 70), race (Asian, White, Black or African, and others), and ethnicity (Hispanic/Latino and others). Six overexpressed genes in 177 patients over a three-year follow-up period were evaluated. Kaplan-Meier estimates revealed survival rates of 84% in the first, 59% in the second, and 38% in the third year. The Log Rank test was used to compare survival curves and Cox proportional hazards models quantified relationships between the covariates. Results indicated that older age groups face significantly higher hazard rates, and White non-Hispanic/Latino patients exhibit poor survival. Significant risk factors include interactions between age and specific genes, as well as time-dependent gene expression. These findings emphasize the importance of tailoring treatment plans considering race, ethnicity, age, and genetic expression to improve patient care outcomes.