Efficacy of Leaf Extracts of Invasive Tithonia diversifolia Against Selected Fungal Pathogens Causing Leaf Spot Diseases

Invasive alien plant species are recognized as a significant threat for species extinction globally. Sri Lanka, been a tropical country has the optimum conditions for distribution of various invasive plant species, and they are a threat to the local biodiversity. Many research have been carried out towards utilization of such plants as a method of successful eradication. Horticultural growers use synthetic fungicides to overcome the problems caused by plant pathogenic fungi, and it has lead to many negative impacts on environment and human health. Consequently, demand for the natural fungicides is increasing. With this background, there is a potential to use invasive plants as natural fungicides due to the presence of bioactive compounds within them. Tithonia diversifolia is an invasive plant species in Sri Lanka. The aim of this study was to find the efficacy of T. diversifolia leaf extracts to inhibit selected fungal pathogens causing leaf spots in ornamental plants. Extractions were done using methanol, dichloromethane and n-hexane. Antifungal activity was tested using standard methods against Curvularia sp., Fusarium sp., and Alternaria sp. Highest inhibition for Curvularia sp. and Fusarium sp. were obtained in n-hexane and methanolic leaf extracts respectively. Minimum inhibitory concentration (MIC) for the Curvularia sp. in n-hexane was 0.0175 g/ml and MIC for Fusarium sp. in methanolic extract was less than 0.0175 g/ml. Leaf anatomical observations revealed three types of trichomes. They were non-grandular and two types of glandular trichomes; capitate and non-capitate. Preliminary tests and Gas chromatographic analysis were done to determine the phytochemical constituents of the three extracts. Results revealed that the three extracts are different from each other where methanolic and dichloromethane were capable in extracting more secondary metabolic compounds. Methanolic and dichloromethane were tested for total phenolics and methanolic extract had the highest content with a 4.4963 μg/ml. Therefore, it can be concluded that leaf extracts from T. diversifolia have the potential to be used as a natural fungicide on disease causing fungi in plants while conserving biodiversity.Keywords: Invasive species, Tithonia diversifolia, Natural fungicides, Phytochemical, Biodiversit

Relations of science students’ academic performance at university level with their gender: a case study at the faculty of science, university of Peradeniya, Sri Lanka

University is an institution for higher education, research, and social development. Hence, the students’ performance at the University is very important as graduates are supposed to become future leaders in this world. There are many factors affecting the students’ performance at the University level. Thus, this study was focusing on assessing the impact of gender on students’ academic performance at University level. This is a quantitative study. Sample of the study was drawn from the Faculty of Science, University of Peradeniya through convenient sampling technique. The sample consisted of 1729 undergraduates from four consecutive batches from 2006 to 2009. There were 822 males and 907 females in the sample. The data were collected through documents from the Faculty of Science, University of Peradeniya and analyzed using MS Excel 2010 and SPSS 17. The study established a relationship between gender of students and their performance measured according to the students’ Grade Point Average (GPA) at the University. The results of the study revealed that the performance of female students is higher than that of males. There were 18% of female undergraduates in 4.00-3.70 GPA range while only 5% of male undergraduates were in the same range. Male undergraduates are prominent in 3.30-3.00 GPA range and < 3.00 GPA.This situation could be due to many inter-related factors such as study habits, aspirations, self-concepts, motivation, other psychological conditions, and some physiological aspects. Thus, an in-depth study has to be conducted to investigate the issue in order to support especially the male students to perform well in their higher education at the University level

Tagetes lemmonii (Atapethiya) as a Potential Candidate for Phytoremediation of Cadmium in Soils

Phytoremediation is one of the eco-friendly strategies used to remove heavy metals such as Cadmium (Cd) from the environment. Tagetes erecta is one such plant used in the phytoremediation of Cd polluted soils. T. lemmonii which belongs to the same genus was used in the current study to investigate its tolerance to cadmium to determine its suitability in phytoremediation of Cd under greenhouse conditions. One-month-old nursery plants were uprooted and transferred into soil containing pots and allowed to establish under greenhouse conditions for one week. Then, soil in pots was treated with 20 mgkg-1, 50 mgkg-1, 100 mgkg-1, and 200 mgkg-1 Cd2+ concentration series with four replicates for each. The control treatments were four pots of plants without Cd2+ added and four pots of soil treated with Cd2+ in each concentration without plants. At two-day intervals, morphological changes such as the height of the plant, and the number of leaves were observed and after 14 days, plants were uprooted and the number of leaves, leaf area, number of rootlets, length of the root, length of the shoot, and total length of the plants were compared among treatments and controls. Cadmium-treated plants, in comparison to the control plants, showed a significant increase in leaf area (p=0.000), fresh weight (p=0.000), dry weight (p=0.000) and a significant decrease in root length (p=0.005 and the number of rootlets (p=0.000) except at 100 and 50 mgkg-1respectively. The increase in plant height (p=0.950), the increase in shoot length (p=0.914), and the decrease in the number of leaves (p=0.322) were not significant. The results suggest that T. lemmonii has a significant survival ability under Cd2+ in soil. Significant total height increments of T. lemmonii plants under Cd2+ treatments suggest that this plant is a hyperaccumulator of Cd2+. Future investigations on anatomical parameters, accumulation, and reduction of Cd2+ in plant tissues and soil respectively will reveal its remediation potential of Cd2+. The results of this study will be utilized to develop phytoremediation strategies for Cd2+ polluted soils using T. lemmonii. Keywords: Heavy metals, Ornamental plants, Eco-friendly, Hyperaccumulatio