Browsing by Author "De Silva, W.A.N.T."

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    Effect of Palm Oil as an Alternative Plasticizer in Tyre Tread Compound
    (Uva Wellassa University of Sri Lanka, 2013) Siriwardana, U.P.; De Silva, W.A.N.T.; Chandrasena, G.; Vithanachchi, J.
    Raw natural rubber and synthetic rubbers are compounded with other substances to have useful articles. Plasticizers play a major role in rubber compounding and petroleum based mineral oil are mostly used as plasticizers for tyre components. But mineral oil is a nonrenewable resource and some of them have been identified as carcinogenic. Naturally occurring oils from agricultural sources have been investigated as an alternative plasticizer in tyre tread compound for several years but there has been no systematic study of the effect of palm oil with respect to the all three types of mineral oils; aromatic, paraffinic and naphthenic oils. The objective of this work was to study the possibility of using palm oil as a cost effective alternative plasticizer for petroleum based mineral oils in tyre trade compound. The experiment was carried out in Research and Development section at Samson Compounds (Pvt) Ltd (DSI Group), Bataduwa, Galle, Sri Lanka. Four types of compounds were prepared with aromatic, naphthenic paraffinic and palm oil plasticizers according to the formulation of material. RSS III-75.000, SBR (Styrene Butadiene Rubber)-25.000, Processing oil-10.000, N330- Carbon Black-50.000, TMQ-Antioxidant-2.000, ZnO-5.000, Steric acid-1.500, 6PPD(N- benzthiazyl sulphenamide)-1.300, DPG (N-diphenylguanidine)-0.200, Sulfur-2.300, Wax-2.000 were used to prepare the tyre tread compound . Mixing was carried out on a laboratory size (160mmx320 mm) two roll mixing mill (Model - COMERI M-89) and the respective cure characteristics were determined using a Monsanto Rheometer (Model 100 FF). Tensile properties and tear strength were tested according to the ISO 37, 1977 using tensile tester (Model TS 1000). Hardness was determined as descri bed in ISO 48, 1979 with a dead load hardness tester. According to the ISO 815, 1991 compression set was tested. Abrasion resistance was measured according to the Din 53516 standards using Abrasion tester (Model GT-7012). Rebound resilience was measured using a Lupke Pendulum according to the ISO 4662-1986 standards. Specific gravity was measured using an Electronic densimeter. Thermal oxidative aging was analyzed as a measure of tensile properties. Tensile properties were tested for four types of compounds after aging over 22 hrs in 70 C and palm oil based compound was tested for tensile properties as a function over time.
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    Effect of Plant Spacing on Big Onion (Allium Cepa L.) Yield in Yala Season
    (Uva Wellassa University of Sri Lanka, 2013) Wasalthilaka, R.T.; De Silva, W.A.N.T.; Dematawa, P.
    Big onion (Allium cepa L.) is an essential condiment in Sri Lankan diet so it is cultivated in Sri Lanka. It mainly grows in Matale, Anuradhapura, Polonnaruwa, Kurunegala districts and Mahaweli H zone. Pusa red, Rampure, Agri found light red, Kalpitiya selection, N53 and Nasic red are the recommended varieties for Sri Lankan conditions considering the factors such as high yield, seed setting ability, storage adaptability, pungency and color etc. Local production of big onion, which is approximately 61,037 MT per year, is not sufficient to meet the annual demand of big onion approximately in between 200,000 - 220,000 MT per year (Department of Census and Statistics, 2011). The major constraint to improve the productivity of big onion in Sri Lanka is the unavailability of good quality seeds of recommended varieties in adequate quantities (Mettananda, 2006). In addition, the poor quality of imported seeds from India is another constraint to enhance the big onion production. Poor quality seeds are characterized by poor germination and poor bulb formation ability and poor quality seeds will result the bulbs which show high thick neck percentage and low yield (Edirimanna, 2003). Minimizing the land area devoted for big onion seed production is a challenge and one way to overcome this challenge is to explore the possibilities of increase in plant density by decreasing plant spacing without affecting seed yield. The objective of the present study was to study the effect of reduction in plant spacing on big onion seed yield of variety Agri found light red which is popularly cultivated in Sri Lanka. Methodology This experiment was conducted at the big onion cultivation site of CIC Agri Busisesses at Palwehera, Dambulla from May 2013 to September 2013.Two plant spacings; 17.78 cm×17.78 cm and 15.24 cm×15.24 cm were used in the experiment which was laid out in a Completely Randomized Block Design (CRBD) with 10 replicates. Agri found light red variety was used to assess the final seed yield of onion. Planting beds were prepared in size 1 m × 3 m. Vernalized medium sized (50-70g/bulb) mother bulbs were selected and treated with Chlorpyrifos 400g/L EC (20ml/10Lof water) and Thiram (80% (w/w) WP) (15g/10L of water).Treated bulbs were planted randomly in planting beds according to the design. Watering was done daily. Oxyfluorfen 240g/L EC (11 ml/10 L of water) was applied in 5 days after planting to control weeds and one or two hand weeding was followed to effectively control the weeds. Recommended concentrations and volumes of fertilizers and other chemicals were applied depending on the growth stages of onion. Hand pollination was done 50 days after planting and it was continued for about 21 days. Matured umbels were harvested in 85-95 days after planting and harvesting was continued for about 30 days. The umbels were air dried for about 15 days. Air dried umbels were sundried and processed to separate seeds from seed heads. Cleaned seeds were dried to reduce the moisture to 8% and weighed. Yield components of big onion plants were assessed during the study period. Number of umbels per 1m , number of florets per umbel, percentage of fertile florets per umbel, number of seeds per fertile floret, 1000 seed weight and total plot yield were measured as yield components. Collected data of yield components were statistically analyzed using Analysis of variance (ANOVA) in MINITAB 15 software.
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    Study on In-Vitro Growth, Rooting and Acclimatization of Baby's Breath (Gypsophila Paniculata L.)
    (Uva Wellassa University of Sri Lanka, 2010) De Silva, W.A.N.T.
    Baby's breath (Gypsophyla panieuktto L.) is one of the important cut flower which used Tissue cultured techniques to propagate commercially. Fragile nature of roots reduced in-vitro rooting and plant survival during acclimatization. Therefore, this research was conducted to improve the in-vitro rooting and plant survival of Baby's breath. Effect of four different gel strengths of MS medium (solid : 9 g 1' agar, semisolid : 4.5 g 1-1 agar, liquid and liquid with coir dust), two different aeration levels (aerated and non aerated) and two different age levels of cultures (four and six weeks aged) on in-vitro growth, rooting and acclimatization of baby's breath was studied through observing shoot height (cm), total dry weight (TDW) (g), total fresh weight (TFW) (g), no. of roots, root length (cm), no. of rooted plants by using 3 replicates and no. of survival plants observed weekly interval up to one month by using 40 plants at Tissue Culture laboratory, Agricultural Research Station, Sita Eliya. Complete Randomized Design (CRD) and MINITAB statistical package were used to analyze the data. Tukey test was used to mean comparison at 5% significant level. Six weeks old plants in aerated semi solid medium was found to be better for in-vitro shooting as it recorded higher survival percentage (83.3%) than four weeks old plants in non aerated semisolid medium (50%) due to high calli growth though it was recorded the highest TDW, TDW/TFW. Six weeks old plants in aerated solid medium was recorded the best performances in in-vitro rooting which recorded 100%,rooting and survival percentage with higher no. of roots (2.83) comparing to the six weeks old plants in non aerated solid medium which recorded 100% rooting and survival percentage with lower number of roots (2.16) at 5% significant level. It can conclude that six weeks old plants in aerated semi solid medium can be used for in4itro shooting and six weeks old plants in aerated solid medium can be used to in- vitro rooting and acclimatization. It could also be suggested that three weeks time period was sufficient for acclimatization of in-vitro grown plants.
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    Study on In-Vitro Growth, Rooting and Acclimatization of Baby’s Breath(Gypsophila paniculata L.)
    (Uva Wellassa University of Sri Lanka, 2010) De Silva, W.A.N.T.; Shirani, D.A.; Kaliyadasa, P.E.
    Baby's breath (Gypsophyla paniculata L.) is one of the important cut flower which used tissue cultured techniques to propagate commercially. Fragile nature of roots reduced in-vitro rooting and plant survival during acclimatization. Therefore, this research was conducted to improve the in-vitro rooting and plant survival of Baby's breath. Effect of four different gel strengths of MS medium (solid : 9 g/I agar, semisolid : 4.5 g/I agar, liquid and liquid with coir dust), two different aeration levels (aerated and non aerated) and two different age levels of cultures (four and six weeks aged) on in-vitro growth, rooting and acclimatization of baby's breath was studied through observing shoot height (cm), total dry weight (TDW) (g), total fresh weight (TFW) (g), no, of roots, root length (cm), no, of rooted plants by using 3 replicates and no, of survival plants observed weekly interval up to one month by using 40 plants at tissue Culture laboratory, Agricultural Research Station, Sita Eliya. Complete Randomized Design (CRD) and MINITAB statistical package were used to analyze the data. Tukey test was used to mean comparison at 5% significant level. Six weeks old plants in aerated semi solid medium was found to be better for in-vitro shooting as it recorded higher survival percentage (83.3%) than four weeks old plants in non aerated semisolid medium (50%) due to high calli growth though it was recorded the highest TDW, TDW/TFW. Six weeks old plants in aerated solid medium was recorded the best performances in in-vitro rooting which recorded 100% rooting and survival percentage with higher no, of roots (2.83) comparing to the six weeks old plants in non aerated solid medium which recorded 100% rooting and survival percentage with lower number of roots (2.16) at 5% significant level. Therefore, it was concluded that six weeks old plants in aerated semi solid medium can be used for in-vitro shooting and six weeks old plants in aerated solid medium can be used to in-vitro rooting and acclimatization. It could also be suggested that three weeks time period was sufficient for acclimatization of in-vitro grown plants. Key words: Solid, Semi solid and liquid medium, Coir dust medium, Aerated vessels, Age of in-vitro plants