Browsing by Author "Senevirathne, A.M.W.K."

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Effect of Hydro and Chemical Priming on Seed Germination and Seedling Growth of Rubber (Hevea brasiliensis)
    (Uva Wellassa University of Sri Lanka, 2020) Jayangani, P.H.D.N.; Nayanakantha, N.M.C.; Senevirathne, A.M.W.K.
    Rubber (Hevea brasiliensis) is propagated through grafting buds of selected clones onto vigorous seedling rootstocks using a green budding technique. Both rootstock and budwood should be of high quality for producing high quality budded rubber plants. Seeds are used in raising rootstock plants of rubber. Being recalcitrant, rubber seeds deteriorate within a few days after falling from trees. The use of old seeds has resulted in low germination and extended germination period in commercial rubber nurseries. The main objective of this study was to investigate the effects of hydro- and chemical-priming on seed germination and seedling growth of Hevea. The experiment was conducted in a nursery at the Rubber Research Institute of Sri Lanka, Dartonfield, Agalawatta. Seeds were soaked in solutions of ZnSO4 (1% & 2%) Urea (0.05%, 0.10%, & 0.15%) and in water (mock treatment) for 24 hours followed by sown in a germination bed according to a randomized complete block design. Un-primed seeds were used as control. Germination percentage was recorded at 7, 9, 11, 13, and 17 days after sowing. Growth parameters of seedlings were recorded at monthly intervals for up to three months after transplanting in polybags. Significantly higher germination percentages were recorded in seeds primed with water (hydro priming), urea, and ZnSO4 after 17 days of sowing when compared to control. However, the highest germination percentage was recorded from the seeds primed with water (mock treatment). No significant differences were recorded in growth parameters of seedlings raised from seeds primed with chemicals or water when compared to those derived from un-primed seeds (control). Therefore, hydro priming may be the simplest and cost-effective priming treatment to improve the germination of rubber seeds. Keywords: Germination, Growth, Seed Priming, Urea, Zinc Sulphate
  • No Thumbnail Available
    Item
    Root Cause Analysis for Warming Delay of Resilient Solid Tire Heel Compound on Warming Mill During Manufacturing
    (Uva Wellassa University of Sri Lanka, 2020) Bandara, B.N.S.; Dilrukshi, N.M.D.; Senevirathne, A.M.W.K.; Wijesinghe, H.G.I.M.
    Solid tires used in heavy-duty applications consist of three distinct parts: heel, cushion, and thread. The heel is the innermost layer which provides the resistance to air permeation while ensuring excellent adhesion to the rim and cushion. More fiber reinforced compounds are used in heel production. But a warming delay for about 8-10 minutes which is more than the specified time limits to warm the compounds before production has been observed when warm the compounds using warming mill. Therefore, this research focused to analyse the root causes of the warming delay of compounds during the warming operation. Minimum torque (ML) and Mooney viscosity (MV) of the heel compound, nip size of the warming mill, thickness, and maturity of the incoming compound sheets were selected as key factors for the warming delay. Multiple regressions analysis and simple linear regression were applied to predict the relationships of these factors with the warming time while using cubic regression to find the effect of nip size on the warming time. According to the results, there is a significant effect of these factors on warming time. Improper mixing of the compounds tends to show high values for MV, ML, and thickness of incoming compounds. The maturity of the compounds and the nip size of the warming mill was selected for further study. According to the two-way ANOVA, there is an interaction between maturity and nip size on warming time. The nip size (mm) was varied from 7 to 10 at 1mm interval and the maturity time of the compounds was varied as 6, 12, 24, and 48 hours. Results revealed that warming time can reduce using 9mm nip size and 48 hours maturity time of compounds at warming mill in the manufacturing process. Keywords: Minimum torque, Mooney viscosity, Nip size, Solid tire heel, Warming delay