UWU Repository :: Browsing by Author "Ranawana, S.R.W.M.C.J.K."

Browsing by Author "Ranawana, S.R.W.M.C.J.K."

Now showing 1 - 20 of 28

Allelopathic Effect of Weeds Extracts on Growth and Yield of Tomato (Solanum lycopersicam L.)
(Uva Wellassa University of Sri Lanka, 2019) Ranaweera, R.A.T.L.; Kaliyadasa, P.E.; Ranawana, S.R.W.M.C.J.K.
The weeds are used as mulch, green manure and in compost production that could favourably or adversely affect on crops due to presence of allelochemicals. Such chemicals can be present in any part of the plant and release to microenvironment by leaching, root exudation, residue decomposition and other processes. This study was undertaken to evaluate the allelopathic effect of four common weed species available in agricultural lands on growth and yield of Tomato (Solanum lycopersicam L. var. Padma) under plant house conditions. The dried vegetative parts of Kura thampala (Amaranthus viridis), Bubovitiya (Clidemia hirta), Panithora (Cassia occidentalis) and Hulanthala (Ageratum conysoides) were used to extract aqueous solutions at different concentrations i.e. 4%, 8%, and 12%. Aqueous solutions were applied two weeks after transplanting and continued at one-day intervals until harvesting. Three replicates were used for each treatment in Complete Randomized Design with a control (water applied). Vegetative and reproductive characteristics of tomato such as plant height, No of leaves, No of branches, stem girth, total chlorophyll content, No of flowers, No of fruits, and fruit weight were recorded. Total polyphenol content of weed species and variation of soil pH and EC were analyzed in monthly intervals. The application of 4% of Hulanthala was shown the positive performances in vegetative growth, while 12% of Panithora reported the lowest values for both vegetative and reproductive growth of tomato compared to other treatments (p<0.05). Further, the highest total polyphenol content was in Bubovitiya and highest fruit weight was reported in the plants treated with 4% Bubovitiya compared to other weed species (p<0.05) with the highest brix value. It can be concluded that the weeds such as Hulanthala and Bubovitiya could be used in preparation of compost or in other organic applications at lower concentrations to obtain better growth and yield performances of tomato.
Amelioration of Cadmium (Cd) Stress in Rice (Oryza sativa L.) by using Selected Soil Amendments and Aquatic Plants
(Uva Wellassa University of Sri Lanka, 2020) Weerakkodi, W.A.G.I.S.; Ranawana, S.R.W.M.C.J.K.; Jayawardana, N.U.
Heavy metal contamination in paddy soil, particularly Cadmium (Cd) has become a serious issue with the potential risk of transferring Cd to the human food chain. Rice plants exposed to high Cd, encounter deleterious effects on growth and yield. This necessitates the need to identify effective and feasible remediation measures to ameliorate Cd stress in rice. Therefore, the efficacy of using selected soil amendments and floating aquatic plants to ameliorate Cd stress in rice was evaluated in this study under controlled environmental conditions using rice variety Bg 250. The experiment was laid out in a Complete Randomized Design with six treatments replicated thrice. Water lettuce (Pistia stratiotes), duckweed (Lemna minor), partially burnt rice husk (RH), and rice straw (RS) were evaluated as the amelioration treatments under two soil Cd contamination levels (5 and 8 ppm). The control was maintained with the only Cd without any amelioration. RH and RS were separately incorporated to Cd treated soil and mixed well at two levels (soil: RH or soil: RS, 1:1 and 2:1 v/v). Upon transplanting of rice, the aquatic plants were introduced to Cd treated pots. Growth and yield parameters were measured at 45 and 75 days after transplanting. Rice grown in the soil medium amended with RH (1:1 v/v) showed significantly higher values for plant height (43±0.2 cm), the number of tillers (3.67±0.03), root length (24.33±1.2 cm), root volume (13.33±0.7 cm3 ), root dry weight (3.17±0.2 g plant-1 ), shoot dry weight (7.44±0.07 g plant-1 ) and seed dry weight (3.12±0.15 g plant-1 ) compared to the control under 5 ppm Cd level. A similar pattern was observed in the other Cd level as well. Interestingly, the aquatic plants reduced the growth and yield of rice possibly due to competition for resources. In conclusion, RH has the potential to be used as an effective soil amendment to ameliorate Cd stress in rice. Field investigations are suggested for making a general recommendation. Keywords: Aquatic plants, Cd stress, Growth and yield, Rice, Soil amendments
Ascorbic Acid and Antioxidant Level of Ceylon Olive (Elaeocarpus serratus) as Affected by Variety, Stage of Maturity at Harvest and Different Methods of Preservation
(Uva Wellassa University of Sri Lanka, 2010) Rasanayaka, R.M.D.D.M.; Sarananda, K.H.; Ranawana, S.R.W.M.C.J.K.
There has been growing interest in the beneficial health effects of edible fruits as well as certain beverages. Their protective mechanisms against chronic-degenerative diseases are thought to be attributed to the presence of natural antioxidants, minerals and vitamins. In this study attempts were made to investigate. the dynamics of changes in ascorbic acid, antioxidant activity, pH, titratable acidity and Total Soluble Solids (TSS) in two varieties of Ceylon Olive (Elaeocarpus serratus); Pol weralu and Heen weralu and to evaluate the quality of Ready to Serve (RTS) drinks prepared from both varieties. Ready to serve drinks made of olive have evaluated for sensory attributes. The level of ascorbic acid was measured using 2, 6-Dichlorophenol-Indopenol (DCPIP) method. Methanolic extracts of fruits and RTS drinks were analyzed by DPPH (1, 1-dipheny1-2- picrylhydrazyl) antioxidant assay. The highest content of ascorbic acid was detected in mature fruits of Heen weralu (66.15 mg per 100 g), while it was lowest (27.30 mg per 100 g) in Pol weralu at ripe. Ascorbic acid contents in RTS drinks Pol weralu and Heen weralu were 13.3 mg per 100 ml and 27.65 mg per 100 ml respectively as compared to 27.30 mg per 100 g and 43.40 mg per 100 g in ripe fruits. The highest value of TSS (17.05) and pH (4) was observed in full ripe Heen weralu. The IC50 (inhibition concentration 50) which represent the antioxidant activity of the methanolic extracts of Po! weralu and Heen weralu were 6.68 and 5.54 mg/ml respectively. Result confirmed that among two varieties, Heen weralu was best in terms of antioxidant activity for both fruit and RTS drink. RTS drink (Heen weralu) was the best sample which showed the highest rank sum value for sensory attributes. Key words: Ceylon Olive (Elaeocarpus serratus), Ascorbic acid, Antioxidant activity, IC50 (inhibition concentration)
Case Study on Waste Water Management Systems Adopted by Different Industries
(Uva Wellassa University of Sri Lanka, 2020) Nishshanka, J.S.; Kaliyadasa, P.E.; Ranawana, S.R.W.M.C.J.K.; Jeewanthi, P.W.
Different industries discharge wastewater with different contaminants in the production process. The heavy metals and other inert materials present in wastewater will contaminate the environment by causing normal drainage systems and natural water resources polluted. Therefore, it is a timely need to study detail on potential industries that generate wastewater and their adoption measures at present to treat the wastewater. With that objective twenty companies that represent eight different industries were identified using secondary data and a structured questionnaire was used to collect data in this study. Data were analysed by descriptive analysis method using Minitab 17 software. The findings of this study emphasized that different industries have adopted different wastewater management systems and analysis methods, however, their wastewater treatment methods at present are of very expensive. Further cost for water consumption by eight different industries is significantly different every month and recorded an average of Rs. 4,700,000.00 per month. Among the eight different industries and the highest cost recorded in the glove industry that costs about Rs. 5,000,000.00 per month. Moreover, 98% of industries prefer to implement a cost-effective wastewater treatment method in which each industry would be able to reuse the water and enhance the efficiency of water usage in a sustainable way. Keywords: Waste water treatments, Heavy metals, Industries, Water reuse
Comparative Efficacy of Selected Insecticides in Comparison with Chlorpyrifos to Control Tobacco Cutworm (Spodoptera litura)
(Uva Wellassa University of Srilanka, 2011) Weerawansha, A.N.R.; Abeysekara, N.N.R.; Ranawana, S.R.W.M.C.J.K.
Cigarette tobacco production is done by the registered farmers of Ceylon Tobacco Company for a pre-trade agreement while other types are grown purely on freelance basis and hence cigarette tobacco production has a better accountability. It is a great matter of concern that, tobacco plant is susceptible for cutworm damage during its life cycle eventually making inconsistent production. It causes a considerable damage to the tobacco plant particularly in the vegetative growth. The cutworm damage is more severe in the field level and in many cases it is present in the nursery level too. The Ceylon Tobacco Company has clearly discovered the demerits of the prevailing pest and chemical control has been playing a leading role for a long period of time as it has become more successful in its efficacies. The company commonly uses Chlorpyrifos 40 EC, a broad spectrum contact insecticide, which belongs to the chemical group of Organophosphate. Direct application of organophosphate insecticides including Chlorpyrifos is toxic and causes environmental pollution. In the environment, the organophosphate insecticide residues and the degraded ingredients pollute the soil, water, air and food. These compounds harm not only non beneficial insects but also beneficial insects, beneficial soil organisms and other animals including human beings. Therefore, usage of Chlorpyrifos is supposed to be phased out from the tobacco cultivations in the island wide. The objective of this study was to find a possible alternative to Chlorpyrifos to reduce environmental toxicity.
Comparison Study on the Growth and Yield Parameters among Seedling and Stem cutting of Thai Kangkong (Ipomoea aquatica)
(Uva Wellassa University of Sri Lanka, 2010) Uthpala, J.P.T.; Malathy, P.; Ranawana, S.R.W.M.C.J.K.; Nilanthi, W.D.G.P.
Thai Kangkong (Ipomoea aquatica Forssk), is one of the most important leafy vegetables in the Southeast Asia. Lack of sufficient quantities of quality seeds at affordable price is one of the major constraints in Kangkong cultivation in Sri Lanka. Even though stem cuttings are used as an alternative planting material, there is no research data available on quality of seedlings and suitable age of stem cuttings. This study was carried out with the aim of comparing yield and growth parameters of seedlings and stem cuttings of different ages and to select the best planting material. Five different ages such as 08, 09, 10, 11 and 12 weeks old cuttings and seedlings were evaluated in a RCBD with four replicates at the research field of HORDI, Gannoruwa (March- July, 2010). As Growth parameters; plant height, length, width and weight of leaves, number of leaves and number of stems, length, width and weight of stems, internodal length, leaf to stem ratio, and as yield parameters; fresh and dry weight per plant and total weight per plot were measured at each harvest in two weeks interval. The data were analyzed statistically with ANOVA using SAS package. Results revealed that the seedlings were best in terms of growth performances such as plant height, length, width and weight of leaves, stem width and leaf: stem ratio compared to stem cuttings only at the initial stage. However, yields of seedlings were not higher than stem cuttings of different ages throughout the experimental period though they had shown quick establishment and good growth performance initially. Among the stem cuttings, 8, 9 and 10 weeks old cuttings showed fluctuation in growth performances while 11 and 12 weeks old cuttings exhibited better growth performances and higher yields in terms of both fresh and dry weight throughout the harvesting period. It is concluded that the 11 and 12 weeks old stem cuttings can be used successfully in the commercial cultivation of Thai Kangkong. Key words: Age of stem cuttings, Ipomoea aquatica Forssk, Planting materials, seedlings, Thai Kangkong
Determination of Cadmium Accumulation and Consequent Responses of Four Different Rice Varieties in Sri Lanka
(Uva Wellassa University of Sri Lanka, 2019) Gunawardhana, S.N.; Jayawardhana, N.U.; Ranawana, S.R.W.M.C.J.K.
The heavy metal Cadmium (Cd) is known to be a widespread environmental contaminant in certain parts of the world. Thus, this study was conducted under controlled environmental conditions to identify a Cd tolerant rice variety with low Cd accumulation. The experiment was laid out in Complete Randomized Design with three replicates. Two traditional rice varieties (Pachchaperumal Ac940 and Goda Heenati Ac798) and two new improved rice varieties (Bg 250 and Bg 352) were grown in pots under different soil Cd levels (0.3, 1.5 and 4.5 mg kg-1). The control was maintained without external Cd. The effect of soil Cd on rice plant was measured with respect to plant height, number of tillers, root length, root volume, shoot and root dry weight and flag leaf chlorophyll content. Amount of Cd accumulated in root, stem and leaves were measured using Atomic Absorption Spectrophotometer. For each variety, Accumulation Factor (AF), Bio concentration Factor (BCF) and Translocation Factor (TF) were calculated. At the highest soil Cd level, Pachchaperumal showed a significant increment in root dry weight compared to its control and all other parameters did not show any significant change except the reduction in number of tillers in Bg 250 compared to its control. (p<0.05). The highest Cd accumulation on roots and stem were identified in Pachchaperumal and Goda Heenati, respectively (p<0.05). No significant difference in Cd accumulation was detected in leaves. The lowest AF (0.72 ± 0.29) was found in Bg 352 and hence it can be identified as a Cd excluder (AF < 1). TF and BCF of Goda Heenati (0.24 ± 0.13, 1.0 ± 0.3, respectively) and Pachchperumal (0.04 ± 0.02, 1.0 ± 0.3, respectively) revealed their potential to be used as a phyto stabilizer (TF < 1, BCF > 1). Moreover, Pachchperumal can be identified as the least affected variety in terms of vegetative growth and hence appeared to be tolerant to above tested Cd levels.
Determination of Economic Injury Level and Economic Threshold Level of Tobacco Cutworm (Spodoptera litura)
(Uva Wellassa University of Sri Lanka, 2019) Sriyantha, K.W.A.R.; Weerawansha, A.N.R.; Ranawana, S.R.W.M.C.J.K.; Edirisooriya, C.H.
Total eradication of Spodoptera litura in tobacco cultivations is virtually impossible and is usually undesirable because it can spell the demise of the pests, natural enemies and can upset the broader economic balance. This experiment was conducted to find out the Economic Injury Level and the Economic Threshold Level of Spodoptera litura in tobacco cultivations. The equation, EIL = C/VD'K where C = management cost per production unit, V = market value per production unit, D’ = damage per unit injury, and K = proportional reduction in injury with management, was used to find the EIL and the equation, ETL = EIL-(EIL⁄2) was used to find ETL. In determination of damage per unit injury, four uniform tobacco seedlings were grown in each treatment plot with three replicates and laid out in a Randomized Complete Block Design. Plants’ exposure time period to the pest was considered as the treatments where the second instar larvae which were mass reared in a culture cage, were introduced at the rates of 0, 5, 10, 15 and 20 to the treatment plots having exposure times of 0, 5, 10, 15 and 20 days, respectively in the 22nd day after transplanting. Pest damage was quantified in terms of damaged leaf area. The management cost per unit production was calculated by taking both pesticide cost and application cost into account. Damage per unit injury was calculated as 1.56 and the management cost per unit production unit was calculated as LKR 4.92. Proportional reduction in injury with management was 0.8 and the market value per production unit was LKR 450.00. Upon substitution of the values in the variables of the formulas, the EIL of tobacco cutworm was determined as 8.76 larvae per 1000 plants and ETL was calculated as 4.38 larvae per 1000 plants.
Determination of Neurotoxic Pesticide Residues in Vegetables by Using Rapid Bioassay Method
(Uva Wellassa University of Sri Lanka, 2019) Senanayake, O.S.; Silva, N.R.N.; Ranawana, S.R.W.M.C.J.K.; Weerawansha, A.N.R.
Pesticide residues in vegetables are determined by expensive and time consuming laboratory techniques. An experiment was conducted to develop a rapid and cost effective protocol for the analysis of pesticide residues in vegetables through Rapid Bioassay of Pesticides Residues (RBPR) method. RBPR is a method that integrates with acetyl cholinesterase (AChE) test to screen the residues of AChE inhibiting neurotoxic pesticides. In this study, 48 vegetable samples (30 non-organic from Kandy central market in Sri Lanka and 18 organics from home gardens) including cabbage, bean, and carrot were tasted for pesticide residues of carbosulfan, diazinon and profenofos using RBPR. AChE was extracted from melon flies (Bactrocera cucurbitae) brain using standard protocol and its inhibition was tested. The inhibition of AChE was assessed by determining the reductions of absorbance in contaminated sample after a fixed reaction period. Calibration curves were developed for each pesticide separately and used for vegetable sample testing. Inhibition of AChE by vegetable extracts was analysed. The highest residue levels of carbosulfan, diazinon and profenofos were found in cabbage (0.00 - 0.53, 0.00- 0.44 and 0.00 - 0.58 ppm, respectively) and the lowest values were recorded in carrot (0.00-0.15, 00-0.29 and 0.00-0.21ppm, respectively) although the difference was not significant (p>0.05) among vegetables. No pesticide residues were detected in organic samples. Moreover, the cost of sample testing was approximately Rs. 450.00 per sample. This bioassay technique can be used for initial screening of neurotoxic pesticide residues in vegetables as rapid and cost effective technique
Determination of Optimum Water Application Interval for Young Tea Plants
(Uva Wellassa University of Sri Lanka, 2020) Senevirathne, K.V.D.K.; Bandara, N.P.S.N.; Ranawana, S.R.W.M.C.J.K.
Tea productivity is highly vulnerable to changes in precipitation. With limited availability of water for irrigation, identification of optimum irrigation interval is necessary to increase water use efficiency. Therefore, a pot experiment was conducted at the Tea Research Institute, Rathnapura to determine the optimum water application interval for young tea plants using one year old uniform tea plants of cultivar, TRI 2027 under controlled environmental conditions (Max and Min temperatures, 32.1 °C and 23.1 °C, respectively; Average sunshine hours, 3.15 h day-1 ). The experiment was laid out according to Complete Randomized Design with four replicates. Four irrigation treatments were applied as daily watering (175 ml plant-1 ), watering at a 4-day interval (750 ml plant-1 ), watering at a 7-day interval (1150 ml plant-1 ), and none watering (control). Plant growth performance was evaluated during the experimental period. The highest evapotranspiration rate (3.02 mm day-1 ) was recorded at daily watering followed by watering at a 4-day interval (2.33 mm day-1 ). Plants watered daily showed significantly higher (p<0.05) plant height (51.4 cm), girth (6.1 mm), leaf dry weight (5.7 g), leaf area (550.5 cm2 ), stem dry weight (3.1 g) and leaf nitrogen percentage (3.15%) compared to control (35.3 cm, 4.1 mm, 1.33 g, 119 cm2, 1.3 g, 2.14%, respectively). Interestingly, growth performances of plants that watered daily were not significantly deviated (p>0.05) from plants that watered at the 4-day interval. There was no significant difference (p>0.05) in root volume and dry weight among different treatments. The results of this experiment suggest that frequent irrigation at least once in four days is important for better establishment of young tea plants. However, before drawing any firm conclusion it is suggested to continue such trials for at least three dry spells. Keywords: Evapotranspiration, Growth performance, Irrigation interval, Young tea plants, Water availability
The Effect of Canopy Thermal Changes on Growth, Yield and Grain Sterility of Three Ultra-short age Rice Varieties under Aerobic and Flooded Conditions
(Uva Wellassa University of Sri Lanka, 2020) Wettasinghe, D.R.Y.; Silva, L.C.; Ranawana, S.R.W.M.C.J.K.; Jeewanthi, P.W.
Canopy Temperature (CT) represents the temperature experienced by the uppermost portion of the crop canopy. CT may better explain the grain sterility associated with high temperatures than the air temperature. Most of the CT related experiments were conducted on wheat. Therefore, Sri Lankan rice varieties were evaluated at the Rice Research and Development Institute, Bathalagoda under two soil moisture conditions to realize the canopy thermal changes and its impact on growth, yield, and grain sterility. This Experiment was arranged in a two-factor factorial in Completely Randomized Design with eight replicates. Factor one was soil moisture conditions, aerobic, and flooded. Factor two was rice varieties; Bg 250, Bg 252, and Ld 253. CT, growth, and yield parameters were recorded. CT at 10:00 h had a positive impact (r=0.76) on grain yield in flooded condition and CT at 9:00 h had a positive impact (r=0.77) on yield in aerobic conditions. Grain sterility increased with increasing CT in both moisture conditions. The number of tillers was negatively correlated with maximum CT, while plant height was positively correlated with minimum CT in both conditions. CT at spikelets opening had a negative impact (r=0.76, 0.80) on pollen fertility at heading and positive impact (r=0.95, 0.85) on grain sterility in both conditions. Moreover, growth and yield performances were superior under flooded conditions compared to aerobic conditions. Interaction between soil moisture and variety was significant for thousandgrain weight and pollen fertility % where highest values were recorded by Bg 250 (29.33 g) and Bg 252 (96.4%) in flooded conditions, respectively. In conclusion, monitoring CT dynamics can be considered as a useful tool to assess the growth and yield performances of rice under varying environmental conditions. Keywords: Rice (Oryza sativa), Canopy temperature, Aerobic & flooded conditions, Grain sterility, Pollen fertility
Effect of Different Concentration of Liquid Nutrient Solution on Potato Tuber Initiation of Two Varieties (Granola And Golden Star) under Hydroponic System
(Uva Wellassa University of Srilanka, 2011) Mohammed Haaris, N.M.; Nugaliyadde, M.M.; Ranawana, S.R.W.M.C.J.K.
The potato (Solanum tuberosum L.) belongs to Solanaceae family. Potato is grown mainly in the up country wet zone of Sri Lanka. Non availability of good quality disease free seeds of desirable varieties at the correct time for planting is considered as the main constraint for increasing the productivity of potatoes in Sri Lanka (Nugaliyadde et al., 2005). The total seed potato requirement in the country is around 19,000 tons per year (anonymous, 2011). At present, very high demand for locally produced high quality seed is created. Technologies, such as aeroponics and hydroponics are developed to produce high quantities of pre-basic seeds tubers locally within a short period (Mazeen et al, 2008). The Agricultural research station, Sita-Eliya was successfully producing minitubers of the variety Granola in hydroponics system. It was producing approximately 80-150 minitubers per plant in short period of time, under hydroponics system. However, a longer period is needed for seeds production of Golden Star than Granola, under hydroponics system because of the longer tuber initiation period which is nearly two months, longer stolon length (> 3 feet) and longer root system. Therefore, tuber initiation period, plant growth, stolon length and root length should be reduced to increase the seed production in a short period of time. Therefore, before releasing a variety it should be capable of supplying a large numbers of seed potatoes according to the requirement. Thus, there was a requirement for producing minitubers from Golden Star variety in a short period of time. This study aims to evaluate different liquid nutrient levels in order to control plant growth and time taken for tuber initiation under hydroponics system.
Effect of Different Irrigation Levels on Flower Initiation and Some Yield Attributes of Black Pepper (Piper nigrum L.)
(Uva Wellassa University of Sri Lanka, 2018) Priyadarshana, R.W.LB.; Subasinghe, H.M.P.A.; Herath, H.M.S.K.; Ranawana, S.R.W.M.C.J.K.
Black pepper (Piper nigruni L.) popularly known as "king of spices" is one of the earliest spices known to man and is the largest commodity in the international spice trade. Pepper is cultivated over an area of 32,800 ha. of Sri Lanka, mostly in Matale, Kandy, Kegalle, Kurunegala and Nuwara Eliya districts. Water scarcity in Dry Zone and some parts of Intermediate Zone has limited the expansion of cultivation and moisture stress may cause variation in yield attributes in black pepper. Identification of optimum irrigation level to get higher yield in black pepper is vital as such information is limited. Therefore, a pot experiment was conducted under protected environmental conditions to find out the variation of yield parameters of black pepper under different irrigation levels. Three irrigation levels (8, 4, 2 L plant-I) were applied weekly to the selected 3 year old black pepper vines of MB-12 variety. There were 3 replicates, grown in 38.7 L pots containing a potting mixture of Reddish Brown Latosolic soil and Compost at 2:1 ratio. Different yield parameters were recorded. Mean values of yield attributes such as number of spikes per plant (81), spike length (11.76 cm), filling percentage (88.9%), number of berries per spike (87.4), fresh weight of berries of 10 spikes (128.1 g) and dry weight of berries of 10 spikes (37.9 g) were significantly higher in black pepper vines with the irrigation level of 8 L plant-' compared to other two treatments. It was also observed that the yield attributes progressively decreased with decreasing level of irrigation in the study. Therefore, an irrigation treatment closer to field capacity (8 L plant-I) is more suitable to get a higher yield in black pepper and further studies are suggested at field level before making recommendations.
Effect of Different Nitrogen Fertilizer Levels on Development of Nicotine in Flue Cured Tobacco (Nicotiana tabaccum)
(Uva Wellassa University of Srilanka, 2011) Chamil, R.M.C.; Abeysekara, N.N.R.; Ranawana, S.R.W.M.C.J.K.
Note: See the PDF Version The tobacco plant is one of the very few crops entering world trade entirely on a leaf basis. It is the most widely grown commercial nonfood plant in the world (Akehurst, 1981). The botanical genus Nicotiana contains over sixty four species. Nicotiana tobaccum is the source of commercial tobacco, which is a member of the family Solanaceae and it is grown as an annual crop for its leaves. Tobacco is the common name of the plant Nicotiana tabacum and to a limited extent of Nicotiana rustica. Cigarette tobacco production in Sri Lanka is done by the registered farmers of Ceylon Tobacco Company for a pre-trade agreement. Nitrogen fertilizer plays a crucial role in tobacco production and large and quality production keenly depends on applied nitrogen fertilizer. However, existing nitrogen fertilizer levels have not fully met the yield forecasting and other cost compensating objectives. Therefore, this experiment was conducted to investigate the effect of nitrogen fertilizer level on the nicotine development of flue cured tobacco and to investigate the best application time of fertilizer on the vegetative growth of flue cured tobacco.
Effect of High Temperature on Growth, Pollen Fertility and Yield Parameters of Selected Rice Varieties in Sri Lanka
(Uva Wellassa University of Sri Lanka, 2019) Rajapaksha, R.M.C.Y.; Illangakoon, T.K.; Ranawana, S.R.W.M.C.J.K.; Jeewanthi, P.W.
Temperature is one of the main environmental parameters affecting growth and development of rice. The mean surface air temperature has increased globally by ~0.74 °C in the last century and will further be increased by ~1.1- 6.4 °C by the end of this century. Therefore, identification and development of heat tolerant rice varieties is an urgent need. This study was conducted to screen twenty rice varieties including newly improved and traditional cultivars for high temperature tolerance based on their growth and yield parameters. Heat tolerant rice variety, N22 was used as the control. The experiment was conducted inside a temperature chamber (35-42 °C) using Randomized Complete Block Design with three replicates for each variety. Eighteen days old seedlings were established with the spacing of 15 x 20 cm as one plant per hill and 40 seedlings per replicate. Growth parameters, pollen fertility, days to 50% heading and 85% maturity, and yield were recorded. Cluster analysis was performed to group the varieties. Accordingly, Kalu heenati was grouped with N22 and was categorized as heat tolerant cultivar. The filled grain percentage and yield per plant of them were 53.5% and 2.19, respectively. Bg 300, Bg 304, Bg 305, Bg 310, Bg 94-1, Bg 352, Bg 357, Bg 358, Bg 359, Bg 360, Bg 366, Bg 369, Suwandal, Pachchaperumal and Pokkali were grouped together and categorized as moderately heat tolerant compared to N22. Sulai, Bg 370 and Madathawalu were grouped together and had the lowest pollen fertility, filled grain percentage and the yield per plant revealing its high susceptibility to elevated temperature. Since none of the tested improved rice varieties were tolerant to high temperature, further research is needed to develop heat tolerant rice varieties for changing future climate.
Effect of Propagator Height on Growth and Survival Rate of Black Pepper (Piper nigrum L.)at Nursery Stage
(Uva Wellassa University of Sri Lanka, 2018) Wijerathne, K.I.M.; Kumara, P.G.A.L.; Ranawana, S.R.W.M.C.J.K.; Jayasinghe, H.A.S.L.
Black Pepper (Piper nigrwn L.) is a spice belongs to family Piperaceae and known as the "King" of spices. Propagationthrough stem cuttings is the common practice.Before field planting, stem cuttings should be kept about 1.5 months inside the propagators and another two months under hardening process at the nursery stage. There is a need to identify the proper height of propagator which gives the highest growth and survival rate. Objective of the study was to increase the growth rate of pepper cuttings to produce field-ready plants within a short period of time by changing the propagator height. The experiment was conducted at the Central Research Station, Matale, Sri Lanka, during August to November 2017 and six different propagator heights (30, 40, 50, 60, 70, and 80 cm) were used as the treatments with 3 replications.Growth parameters such as number of leaves,shoot length, root length, number of roots and root volume and survival percentage were analyzed using ANOVA technique. Propagator with 50 cm height produced plants with significantly highest performance with respective to the above growthparameters except number of leaves compared to 60 cm propagator (current practice).Survival percentagesin 50 cm and 60 cm propagators are 99.3% and 98.6% and root volumes were 0.85 cm3and 0.73 cm3,respectively. Therefore, propagator with 50 cm height can be recommended to propagate pepper cuttings within shorter period of time in place of 60 cm propagator.
Effect of Root Pruning on Growth and Yield Performance of Potatoes Grown in Aeroponic System
(Uva Wellassa University of Sri Lanka, 2020) Abeysundera, K.M.; Abeythilakarathna, P.D.; Ranawana, S.R.W.M.C.J.K.; Perera, D.Y.A.D.D.
Production of potato mini-tubers through aeroponics is gaining popularity with the increased demand for more efficient, high-quality seed production methods. Root zone with mini-tubers of potatoes is always wetting with a nutrient solution in the aeroponic system making roots more vulnerable to fungal infections. Disease infected roots can be removed by practicing root pruning. However, proper assessment is needed to identify the effect of root pruning on tuber production. Therefore, the effect of root pruning on growth, mini-tuber yield and, quality of aeroponically grown different potato varieties were evaluated at the Agricultural Research Station, Seetha-Eliya during Maha season 2019-2020. Four levels of root pruning (no pruning and pruning ½, ¼, ¾ of the potato roots, respectively) and three potato varieties (Granola, Red La Soda, and Arnova) were tested using two-factor factorial design of CRD with four replicates. Growth, yield, and quality parameters such as specific gravity, starch, and dry matter content were recorded. Data were analysed using SAS statistical software. Plant height, compound leaf width, terminal leaf length & width, and stolon number were not significantly affected by root pruning or variety (p ≥ 0.05). The interaction effect between pruning level and variety was significant for mini-tuber yield where the highest value was recorded by Granola with no root pruning (235.98 g) which was statistically similar to the value recorded by ¼ level of root pruning (235.72 g). The highest starch (8.06%) and dry matter (13.53%) contents of mini-tubers were found in Granola at ¼ level of root pruning and no pruning, respectively. The specific gravity of mini-tubers was not affected by root pruning or variety. In conclusion, pruning at a level of ¼ of the total root length can be recommended for aeroponically grown potato with root infections as it does not cause any yield or quality reduction. Keywords: Aeroponics, Growth, Yield, Potato mini-tubers, Quality, Root pruning
Effect of Stage of Maturity at Harvest and Artificial Ripening on Postharvest Quality of “Red Lady” Papaya
(Uva Wellassa University of Srilanka, 2011) Gamage, P.G.N.C.; Ranawana, S.R.W.M.C.J.K.; Sarananda, K.H.; Senarathne, S.M.A.C.V.
Papaya (Carica papaya L.) is one of the major fruit crop cultivated in tropical and sub-tropical zones. Over 10.48 million tonnes of fruits were produced in 2009 on about 420,279ha (FAO, 2009) worldwide. It is consumed as a table fruit in both fresh and processed forms and cultivated mainly for its nutritive value (Singh, 1990). Tropical fruits are highly perishable and need to be handled with extreme care from the time they are harvested until they reach the consumer. A considerable quantity of production is lost in the postharvest phase. According to the Department of Agriculture, the highest percentage of postharvest loss is found in papaya (46 %) compared to banana and pineapple (20-30 %). Many of the indigenous as well as introduced varieties of papaya fruits are subjected to the post-harvest losses due to a range of disease causing agents such as Fusarium moniliforme,Lasiodiplodia theobroniae, Photnopsis caricae-papayae, and Colletotrichumgloeosporioides. Red Lady is an introduced variety to Sri Lanka from Taiwan. Harvesting, handling and transporting of papaya are very difficult since it is having an easily damageable soft skin. Many people harvest papaya at the immature stage to avoid these physiological damages but those fruits do not ripe correctly and give off flavours. The peel colour and flesh colour also do not develop well and skin gets damaged due to high latex exudation in immature fruits during harvesting. Those damages cause negative consumer preference in the market place. Uneven ripening causes poor quality peel colour and flesh colour in Red Lady papaya. Dark yellow peel colour and the thick red colour flesh in ripe fruits attract the consumer (Sarananda and Wijesundara, 2009). Papaya is oftenharvested at a mature but unripe condition, and is subsequently allowed to ripen further. Under natural conditions, they ripe slowly, lead to weight loss, desiccation and uneven ripening. Thus, fruit ripening is a very important process in order to get good quality ripened fruits for the consumption. This study was conducted to select the best harvesting stage for artificial ripening using Ethrel ((2-chloroethylphosphonic acid), effect of artificial ripening on postharvest quality considering the peel and flesh colour and disease severity of the red lady papaya to minimize the post-harvest losses.
Effect of Storage Conditions on Seed Dormancy and Vigor of Newly Developed Rice Varieties
(Uva Wellassa University of Sri Lanka, 2018) Rathnayaka, R.M.S.N.; Illangakoon, T.K.; Kaliyadasa, P.E.; Ranawana, S.R.W.M.C.J.K.
Inappropriate storage conditions and seed dormancy affect the seed quality resulting poor germination and loss of vigor. A study was conducted to identify the effect of storage conditions on seed vigor and dormancy of newly developed rice varieties. The experiment was laid down in a split plot design with four replicates. Harvested seeds of 24 varieties were dried and stored at two storage conditions viz. cold storage (18-20 C) and ambient (30-32 C) separately. The duration for dormancy of each variety was considered as the period from harvest till germination reached up to 85% and determined using the germination test at one week interval. Seed vigor was investigated by electrical conductivity test and cold test. There was an interaction between storage condition and variety (P 0.05) for dormancy period. There was a significant effect of storage condition for seed vigor and dormancy. No significant differences (P > 0.05) in vigor index between two storage conditions were observed. Varietal variation was observed for dormancy, conductivity and vigor index. Bw12-574, Rathusuduru and Ld11-7-3-1 showed longer dormancy periods under cold (90-100 days) and ambient (48-83 days) storage. At13-3048, At373, Bg15-520 and Ld12-6-22-1 showed shorter dormancy periods under cold and ambient storage (32-62 and 20-27days, respectively). Bw272-6b, Rathusuduru and Ld12-6-22-1 showed less vigor due to high conductivity values (0.08-0.24 dS m-1) and Bw272-6b, Rathusuduru and Bw14-509 showed less vigor due to lower vigor indexes (18.5-22.2). At13-1543, At13-3791, WAS4-2-3 were considered as high vigor varieties due to lower conductivity value (0.05-0.12 dS m-I) and higher vigor indexes (27.2-25.5). Since cold storage increases dormancy period it can be recommended for rice seeds with shorter dormancy period to store them longer without breaking the dormancy. Results of this study revealed the importance of manipulating storage conditions to enhance seed vigor and lengthen the dormancy period.
Effect of Technically Specified Rubber (TSR) Variations on Rheological Properties of Soft Compound of Solid Tires
(Uva Wellassa University of Sri Lanka, 2018) De Silva, D.A.W.Y.; Wickrama Arachchi, P.K.; Ranawana, S.R.W.M.C.J.K.; Abhiram, G.
The soft compound of solid tires is used to produce the middle section (cushion) of the solid tires which enhanced to provide the cushioning effect. Medium hardness, low heat buildup, high elasticity and high resilient are the most expected characteristics from the soft compound. TSR from different suppliers may lead to unexpected deviations in the theological properties of the soft compound produced. Such deviations in the rheological properties significantly affect the performance of soft compound. The objectives of this study were to investigate the effect of TSR variations of suppliers on rheological properties of soft compound and identify the raw rubber property or properties which cause such variations. Rheological properties such as t52 (Scorch time) and tc90 (Optimum Cure time) of soft compound produced from TSR supplied by three different suppliers (thirty samples each) were measured to check the effect of TSR variation of the suppliers on rheological properties of soft compound. Raw rubber properties such as dirt content, ash content, volatile matter content, nitrogen content, Wallace plasticity (Po) and Plasticity Retention Index (PRI) of three samples of TSR from each supplier were measured to identify the cause of the TSR variations. The results revealed that the rheological properties of the soft compound are significantly affected by the TSR variation of the supplier (p < 0.05). Dirt content, ash content, volatile matter content, nitrogen content were having a significant effect for the resulted variation of TSR (p < 0.05). Findings of this study will be useful in selecting the best TSR supplier to produce best soft compound in solid tire manufacturing. Keywords: Rheological properties, Soft compound, Solid tires, Technically Specified Rubber

Browsing by Author "Ranawana, S.R.W.M.C.J.K."

Results Per Page

Sort Options