Browsing by Author "Prematilake, K.G."
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Item Evaluating the Seed Germinability and Growth Performances of Nursery Plants of Alternative Shade Tree Species in Tea Plantations(Uva Wellassa University of Sri Lanka, 2016) Suman, M.; Prematilake, K.G.Tea is a shade loving plant. Hence, shade trees are necessary to provide shade for tea as well as to add green biomass to soil by regular lopping. There are two species of shade tree species such as Grevillea robusta, Derris mycrophylla and Albizzia moluccana which cultivate as high shade trees in the Uva region and Dadap (Tithonia diversifolia) is cultivated as low shade species. Hence, there was a scarcity of shade tree species in tea plantations, but there is a very high demand for alternative shade tree species in all tea growing regions particularly to face to the sudden drought conditions. An experiment was conducted to study the germination and growth performances of three potential tree species such as Derris mycrophylla, Cassia spectabilis and Techoma stance to provide shade for tea in comparison with recommended shade tree species such as Albizzia moluccana and Grevillea robusta. Tetrazolium test was used to test the viability of seeds. Germination of seeds was tested after subjecting seeds to different pre-treatments such as pre-soaking in water at ambient temperature, hot water treatment, chemical treatment (98%, H2SO4) and mechanical damaging. The highest viability percentage was shown by Cassia spectabilis followed by Derris mycrophylla and Albizia mollucana. But, Techoma stance seeds did not show any viability. The highest germination percentage was recorded with Cassia seeds pre-treated with mechanical damaging of seed coat. Whereas, Albizia mollucana and showed the highest germination rate with hot water treatment followed by mechanical damaging. Mean growth rate was also the highest with Cassia spectabilis followed by Derris mycrophylla and Derris mycrophylla. Leaf number per plant was more or less same in all species. Growth rate of Techoma stance was relatively lower than that of Grevillea robusta, but the leaf number per plant is other way round. Cassia spectabilis had the highest viability percentage, highest growth rate compared with other alternative species such as Techoma stance and Derris mycrophylla as far as pretreatment for the germination and growth rate are concerned Cassia spectabilis was the best. Keywords: Pre-treatments, Viability, Germination, Shade trees, NurseryItem Impact of Pesticide Use Practices on Farmers' Health: A Case Study in Wijayagama and Eheranda in Matale District(Uva Wellassa University of Sri Lanka, 2016) Dulanjalee, K.G.A.P.; Prematilake, K.G.; Weerawansha, A.N.R.; Sumith, J.A.The study documented a serious consequence of the indiscriminate use of pesticides for the farmers' health in Wijayagama and Eheranda, two rural villages located in Naminigama Grama Niladhari division of Wilgamuwa Divisional Secretariat division in Matale district. The farmers residing in both villages, who applied pesticides by themselves, were selected as the sample and it was 110. Primary data were collected through pre-tested questionnaires. Secondary data were collected from the reports of National Census and Statistical Department and Office of the Registrar of Pesticide. Over 55% of farmers were found to be overusing pesticides. Only 11% of farmer's usage of personnel protective equipment to be called as "good" and 89% belongs to "bad" usage of personnel protective equipment. The 16% of the farmers not affected, 43% lightly affected, 30% moderately affected, 11% highly affected and nobody was very highly affected. Therefore, only 16% of the farmers were not affected and 84% of the farmers reported to having one or more considered acute pesticide poisoning symptoms, after routine application of pesticides. Considered acute pesticide poisoning symptoms occurrence was positive for 85% of the farmers and negative for 15% of the farmers for the previous cropping seasons, during or after pesticide application. This study gave indications that a majority of farm households do not take cognizance of the long term and short term health hazards of pesticides in pesticide use practices and acute pesticide poisoning symptoms are under- reported in Wijayagama and Eheranda in Matale district. Keywords: Pesticide use practices, Farmers' healthItem Investigating the Association of Vesicular Arbuscular Mycorrhiza (VAM) with Commelina benghalensis Weed Species(Uva Wellassa University of Sri Lanka, 2019) Herath, H.M.M.P.S.; Prematilake, K.G.; Gunasena, H.M.P.M.A study was conducted to investigate an association between Vesicular Arbuscular Mycorrhiza (VAM) and Commelina benghalensis weed. In field experiment 1 carried out at Wewessa estate consisted of 2 treatments, i.e. tea alone and a tea plot infested with C. benghalensis. In field experiment 2 carried out at the Uva Wellassa University, tomato was planted as an indicator plant in association of C. benghalensis. Single nodal stem cuttings of C. benghalensis was planted at 4, 8 and 12 cuttings per plot as treatments. Experiment was undertaken in a randomized complete block design with four replicates. Plant height of tomato and creeper length of C. benghalensis were measured weekly. Soil N, P and pH were analysed before and 3 months after commencement and tea yield was measured weekly at Wewessa estate. In both experiments VAM spore counts and root colonization percentages were calculated at 6 weeks’ intervals. Dry weights of both C. benghalensis and tomato were measured. A significantly higher VAM colony count (19.5) and spore count (21) were reported in the treatment of Tomato planted with 12 C. benghalensis cuttings per plot 3 Months After Planting (MAP) when compared to that of Tomato planted with 4 cuttings per plot and the initial root colony count. Phosperous level in the rhizosphere was also significantly (p<0.05) increased when tomato planted with 12 C. benghalensis cuttings per plot, 3 MAP when compared to that of tomato planted with 4 cuttings per plot. In the field trial, there was no any significant (p>0.05) difference in tea yield between tea alone and tea planted in association of C. benghalensis. The study concluded that there is an association between VAM and P solubilization in C. benghalensis. This association has favourably affected on tea and tomato growth.Item Investigating the Association of Vesicular Arbuscular Mycorrhiza (VAM) with Commelina benghalensis Weed Species in Tea Lands(Uva Wellassa University of Sri Lanka, 2020) Wijesingha, W.A.H.M.; Prematilake, K.G.; Silva, P.D.P.M.D.A study was conducted to investigate the association of Vesicular Arbuscular Mycorrhiza (VAM) with Commelina benghalensis (Girapala), which is an aggressive weed infesting in tea cultivations. A field experiment was carried out at Wewessa estate, Badulla from September to December 2019. Four treatments i.e. Tea infested with C. benghalensis slashed at 3 weeks interval, Tea infested with C. benghalensis slashed at 6 weeks interval and Tea with no weeding for 3 months and tea alone (weed-free), were included. VAM spore count and root colonization percentages were calculated at 6-week intervals. Soil Phosphorus was analyzed and tea yield was measured. VAM spore count and root colonization percentage were significantly (p<0.05) higher in two treatments with C. benghalensis compared to those of no weeding treatment. Spore counts were recorded as 190, 200 spores/100g of soil in the treatments of which C. benghalensis was slashed at 3 and 6 weeks interval, against 120 in no weeding treatment. Root colonization was also reported as 56.7%, 60%, 39.4% in tea infested with C. benghalensis slashed at 3 and 6 weeks interval, and no weeding treatments, respectively. Significantly higher levels of soil Phosphorus (241 ppm and 237 ppm) were also reported from two treatments of C. benghalensis slashed at 6 and 3 weeks intervals compared to no weeding (230 ppm) treatment at the end of 3 months. There was no significant difference in tea yield between treatments. The study concluded that there is an association of VAM with C. benghalensis and P solubilization is taken place with VAM colonization in the rhizosphere of C. benghalensis. VAM association with C. benghalensis weed has thus been favorably affected on tea growth. Keywords: Aeroponics, Growth, Yield, Potato mini-tubers, Quality, Root pruningItem Investigating the causes for poor control of Crassocephalum crepidioides (Thandam pillu) weed by Glyphosate in the Uva region(Uva Wellassa University of Sri Lanka, 2015) Priyani, A.G.S.; Prematilake, K.G.Weed management in tea field is great importance among other agronomic practices as weeds are the number one pest and they can lower the productivity of tea by 10 to 50 percent due to their competition for light, space, water and nutrients. Various weed management practices are used in tea cultivation such as manual, mechanical, cultural, chemical, and biological methods. Chemical weed control is the most convenient and effective methods among the various weed management techniques available. Unlike manual weeding, chemical weed control minimizes soil erosion and largely eliminates the loss of plant nutrients, which were carried away in the weeds removed from the field and less labour required. Other than normal classifications, weeds can be grouped as common weeds, hard-to-kill weeds and favorable herbs. Among the weeds Thandam pillu was considered as a common weed, but it is becoming a hard-to-kill weed. It was already become resistant to Paraquat herbicide and now there are complaints that it is difficult to control even by Glyphosate herbicide. Recent investigations under up country conditions have shown that such poor control is attributed to the dosage of Glyphosate applied and the age or growth phase of weeds, (Pre matilake and Nawarathne, unpublished). Therefore, the objective of the present study was to elucidate the possible causes of poor control of Thandam pillu weed under Uva region. Materials and methods An experiment was carried out at the Uva Wellassa University during July-August 2014. C.crepidioides weed plants at five different growth phases such as 3-4, 5-6, 7-8, 9-10 and > 10 leaf phase, were collated from Ury Estate and they were planted randomly on raised beds, (30 plants per each growth phase) and left for 2 weeks to established. Two Glyphosate (36%) dosages (5 ml/L and 3 ml/L) were sprayed on plants by isolating the plant to prevent contaminations with other plants. An untreated Control was also maintained. Herbicide application was done as drenching application, by using hand sprayer during morning. The degree of chlorosis, wilting of leaves, scorching and drying of leaves and leaf fall occurred at 7, 14 and 21 days after application (DAA) of Glyphosate. Thandam pillu weed was observed and rated. Dead plant percentage, dry weight of viable plants and recovery of plants were recorded at 21 DAA. Results and Discussion Chlorosis was more prominent at 7 DAA and it occurred at significantly higher rate with Glyphosate at 5 ml/L than at 3 ml/L at 3-4 and 5-6 leaf growth phases. Leaf wilting was more prominent at 14 and 21 DAA and it occurred at significantly higher rate with Glyphosate at 5 ml/L at all five growth phases. Scorching and drying of leaves took place at the same rate with both Glyphosate at 5 ml/L and at 3 ml/L at 3-4, 5-6 and 9-10 leaf growth phases. However, symptoms were more severe with Glyphosate at 5 ml/L than at 3 ml/L at 7-8 and >10 leaf phases. Leaf fall also occurred more severely with Glyphosate at 5 ml/L than at 3 ml/L at 7-8 leaf phase. Mean percentage of dead plants of C.crepidioides was significantly higher with Glyphosate at 5ml/L than that of 3ml/L at all growth phases. There was no death of the weed after phase 3 onwards with Glyphosate at 3ml/L and at phase 4 and 5 with Glyphosate at 5ml/L.Item Investigating the Potential of Using Non-Conventional Materials as Mulches in Tea New Clearings in the Uva Region(Uva Wellassa University of Sri Lanka, 2019) Wasala, W.M.O.S.K.; Prematilake, K.G.The unavailability of herbicides to manage weeds in tea has been lead to contemplate on cultural weed management strategies. Hence, a field experiment was conducted to investigate the potential of using non-conventional materials as mulches in a tea new clearing at Demodera Tea Estate in Badulla during September to December 2018. Shoots of Cassia spectabilis (Kahakona), Acacia mangium, Megathyrsus maximus (Guinea grass) and Silver/Black artificial mulch were used as treatments and Mana grass (Cymbopogon confertiflorus) was used as the Control. Each mulch was spread on randomly selected plots each sized 3 × 3.6 m at a rate of 1 kg dry matter m-2 and replicated quadruplicate. The rate of ground exposure as a percentage was visually assessed with the decomposition of each material weekly. Weed density (counts per 0.09 m2) was measured at weekly intervals and the weed dry weight was measured at four weeks intervals. A bioassay was also carried out to study any allelopathic effect of mulches on the suppression of weeds. Tea plant height and diameter were also measured before and 8 weeks after mulching (WAM). Half-life (time taken for the 50% ground exposure) of 8.8, 11.5, 10, 12 weeks was recorded for C. spectabilis, A. mangium, M. maximus and C. confertiflorus, respectively. Ground exposure in artificial mulch was remained as zero and weed density was also zero even at 12 WAM. Weed density and weed dry weight were significantly lower in C. spectabilis and C. confertiflorus treatments and there was also weed growth suppression due to their allelopathic effect. Tea growth was not significantly affected by any treatment. Artificial mulch was found to be more durable and effective than plant based mulches. Although C. spectabilis mulch was less durable, the weed occurrence with it was relatively lower than that of other plant mulches.Item Investigation of Possible Vesicular Arbuscular Mycorrhizal (VAM) Associations in Prevalent Weeds in Tea Cultivations of Uva Region(Uva Wellassa University of Sri Lanka, 2019) Ranasinghe, D.H.Y.A.; Prematilake, K.G.; Silva, P.D.P.M.D.; Gunasena, H.M.P.M.A study was carried out to investigate the possible Vesicular Arbuscular Mycorrhizal (VAM) associations in some prevalent weeds. VAM association in roots of some weeds is said to be favourable for crop growth. Weed root samples from the rhizosphere of Ageratum conyzoides, Axonopus compressus, Bidens pilosa, Borreria latifolia, Cleome rutidosperma, Drymaria cordata, Eleusine indica, Erigeron sumatrensis and Oxalis corniculata were collected from two tea estates, Wewessa and Spring Valley in Uva region covering IM1a agro-ecological zone. Soil samples from the rhizosphere of each weed were collected and tested for soil pH. VAM root colonization percentages and spore counts were calculated using Grid method and Doncaster’s counting disc method, respectively. The highest VAM count was recorded as 47.67% with Axonopus compressus weed and the lowest as 20% with Eleusine indica. The highest spore number was counted as 265 with Borreria latifolia and the lowest as 70 with Axonopus compressus. The mean pH was within the range of 6.2 to 4.8 at 19 ± 1 °C in two locations.