Browsing by Author "Ranasinghe, C.S."

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    Approach to Screen Coconut Varieties for High Temperature Tolerance by in-vitro Pollen Germination
    (2010) Ranasinghe, C.S.; Waidyarathna, K.P.; Pradeep, A.P.C.; Meneripitiya, M.S.K.
    Successful fruit set in coconut depends on several reproductive processes including pollen quality, pollen gennination percentage (%PG) and pollen tube growth processes. Three preliminary experiments were conducted at the Coconut Research Institute, Lunuwila, Sri Lanka to quantify the response of in vitro pollen gennination in coconut to time ofincubation, the response ofin vitro pollen germination and pollen tube growth to temperature and to detennine the cardinal temperatures (Tmin Topt T_) ofcoconut varieties for in vitro pollen gennination. Pollen was collected from palms of six cultivars I varieties expressing variable tolerance to abiotic stresses. Pollen gennination and pollen tube length were recorded after incubation in artificial growth media at the respective treatments. For pollen collected during October I November periods, cultivars differed for in-vitro pollen gennination percentage with a mean values of 23%. The mean cardinal temperatures (Tmin Topt Tmu) averaged over cultivars were 20.0 nc, 28.0 °c, and 38.8 nc, respectively, for pollen gennination. The information generated in this study will be tested in different seasons of the year for consistency and used to develop a heat tolerance index for coconut. This index will be used to identify coconut varieties suitable for high-temperature prone areas. In addition, the identified cardinal temperatures and response functions could be incorporated into process-based coconut models to increase prediction accuracy under current extreme and projected future climates.
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    Changes in Soluble Sugars, Sugar Profile, Starch and Proline in Developing Coconut (Cocos nudfera L.) Inflorescences
    (2008) Bandupriya, H.D.D.; Weerakoon, L.K.; Ranasinghe, C.S.; Fernando, W.P.K.K.
    Changes in soluble sugars, sugars profile, starch and proline levels in inflorescence rachill; from individual coconut palms were investigated during inflorescence development with the aim determining a possible correlation between these characters and morphogenic potential inflorescence tissues. Rachillae for analysis were collected from unopened inflorescences of-1 to -] stages (considering the youngest open inflorescence as 0 stage) in decreasing order of maturity (-stage is the most mature stage whereas -13 is the most immature stage). Important differences amoi the maturity stages were observed for total sugars. In very tender inflorescences (-13 and -12), tl total sugar content was very low whereas a gradual increase was observed from -11 to -7 stages, wi -7 stage having the highest level. The total sugar content in more mature inflorescences w; relatively low, with the exception of -2 stage, which had a high total sugar content. In regard sugar profiles, sucrose, fructose and glucose were the main soluble sugars present in cocon inflorescence and sucrose was the most abundant sugar hi -5 to -9 maturity stages. Total solub sugars and sucrose in maturity stages from -5 to -9 showed a very similar variation and significant higher levels of sucrose were observed in -6 to -8 stages. The proline content in the mature stages, to -3, was significantly lower than in the other stages with no significant variation in the stages -4 -11. The pattern of variation in starch content was similar to that of proline which decreased wi increasing maturity of inflorescence. In view of the results obtained, the higher accumulation < "sucrose and total sugars in -6, -7 and -8 stages may have some significance in morphogenesi especially as an energy source. The 10 cm length inflorescence that responds better for callusing fal within this range. Thus total sugar and sucrose content may be possible biochemical markers fi asses sing the morphogenic potential of inflorescence explants.
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    Dry Matter Requirement for Growth and Respiration of Coconut
    (2015-06) Ranasinghe, C.S.; Premasiri, R.D.N.
    The present study detennined the dry matter (DM) requirement for potential growth (PGR), growth respiration (Rg) and maintenance respiration (Rm) of fru its, leaves, stem and root system of adult coconut palms (25-26 years) ofTall x Tall cultivar under resource-un lim iting conditions. The total OM requirement ofa palm was about 21 kg/palm/month and 63% of that total was required for growth and respiration of vegetative organs (leaves, stem and roots) whilst the rest (37%) was for fruits. Srmilarly, the DM required for respiration (62%) was nearly two third ofthe total requirement of a palm and the balance 38% was required for growth of organs. The total dry matter requirement (TOMR) of individual fruits varied with developing stage and TDMR offruits / palm varied between months and years depending on the fru it load of different development stages. Irrespective of the year, TOMR of fruits was highest during November to February (about 10-11 kg/palm/month) and lowest in June-July (about 5-6 kg/palm/month). However, the OM requirement of vegetative organs (a total of approximately 13 kg/palm/month) did not vary between months.
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    Tender coconuts for export market: evaluation of cultivars and improved protocol for extended shelf-life
    (2009-04) Ranasinghe, C.S.; Madurapperuma, W.S.; Nainanayake, N.P.A.D.; Mendis, H.C.; Fernando, W.P.K.K.