Browsing by Author "Seneviratne, P."

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Acclimatization of micropropagated plants of Hevea
(Rubber Research Institute. Agalawatta, 1993) Seneviratne, P.; Wijesekera, G.A.S.; De Soysa, G.M.
In vitro produced Hevea shoots were successfully acclimatized to outdoor conditions by controlling the ambient conditions, mainly the humidity. Shooots, longer than 5 cm and with some leaves attached performed better. Shoots without roots produced shoots soon after their transfer to soil and the root development and the acclimation succes was better than in the rooted shoots. Use of a concentrated auxin solution, to soak the bases of the shoots or to incoroperate into soil improved root induction. The growth of the aerial part and the root system of the micropropagated plants were comparable to those of embryo cultured plants, up to one year of growth, but the field performance is yet to be monitored.
Comparison of yields between budgrafts and mother trees in Hevea brasiliensis Muell. Arg.
(Rubber Research Institute . Agalawatta, 2007) Pathiratna, L.S.S.; Wijesuriya, W.; Seneviratne, P.
The correlation between branching and the tree growth of Hevea brasiliensis (Muell.Arg.)
(Rubber Research Institute of Sri Lanka. Agalawatte, 1996) Seneviratne, P.; Nugawela, A.; Ramawickrama, D.
The main objective of the present study was to see whether there is a correlation between the number of branches and the tree grwoth in hevea brasiliensis. Considerable variation in brancing habits is observed among the trees of different clones. Also, some clones such as RRIC 121 show less brancing when compared to other clones such as RRIC 100 indicating brancing is also a clonal characteristic. Canopy architecture too, shows differences among trees within a clone. Highly significant positive correlation was observed between the number of branches and the tree girth for all clones tested for trees aged from one year to seven years. The correlation between the canopy distribution (grouped as very good, good or poor) and the tree girth was also positive.
The effects of the basic medium and the carbohydrate content on shoot cultures of Hevea brasiliensis
(Rubber Research Institute. Agalawatte, 1996) Seneviratne, P.; Flegmann, A.W.; Wijesekera, G.A.S.
Woody Plants Medium (WPM) was superior to murashige and skoog medium (M S), which showed better axillary bud growth of both juvenile and mature shoot materials. The effect was more pronounced in later passages, in particular, on the survival rate of the cultures. Most of the cultures grown on M S medium did not survive more than 24-28 weeks, while on WPM medium cultures survived for more than one and a half years, until the experiment was terminated. The level of sucrose in the medium also had an effect on the growth of the primary axillary shoots, specially the length and the leaf growth. The length of primary axillary shoots incresed with the increasing levels of sucrose in the medium up to 10 per cent with clonal materials. Explants did not survive beyond 8 weeks when the medium was not supplied with sucrose.
Factors affecting the budgrafting success and the scion growth of young budding of Hevea
(Rubber Research Institute. Agalawatta, 1994) Seneviratne, P.; Nugawela, A.; Samarakoon, S.M.A.
The size of the bag in which the stock plant is grown seems to have an effect on the growth of the seedling; from the three bag sizes tested, ie 15 x33 cm, 18 x 38 cm, 23 x 45 cm, it was found that the diameter the number of leaf whorls of the seedling increased with the increase of the bag size.Though the differences are not statistically significant, the budding success too increased in the same pattern. There was no effect of the bag size on the growth of the scion. The two types of buds, axillary scale, showed no difference either on bud grafting success or on the growth of the scion. The growth stage of the top most leaf whorl of the stock plant, either mature or immature, had no effect on the peeling qualities budgrafting success though a little higher budgrafting success was seen when the top flush was immature. There was an effect of the snag, on the scion growth; when the snag was shorter the sprouting took place earlier but, the scion growth was slightly poor as was evident by the diameter the length of the scion. Long snags delayed the sprouting , but the scion growth was better. The best growth of the scion was obtained when the snag was long with a few leaves attached to it.
The growth, phase change and rejuvenation of trees with special reference to Hevea brasiliensis (Muell.Arg.)
(Rubber Research Institute. Agalawatte, 1996) Seneviratne, P.
The growth of seedlings and buddlings of rubber is periodic and the growth during the first 3-5 years is purely vegetative and the trees grow upward without brancing. Also rubber tree undergoes the phase change during its development process. Trees attain the mature phase in 5-6 years of age which is generally characteristic by flowering and wintering. As for as the rubber industry is concerned, the physiological and biochemical characteristics related to the mature phase, such as slow growth rate, losing of root regeneration capacity, high content of phenolic compounds etc. are all undisarable. All improved clonal materials belong in this phase.
Micropropagation of juvenile and mature Hevea brasiliensis
(1991) Seneviratne, P.
The problem of surface sterilization of shoot materials of Hevea
(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Seneviratne, P.; Flegmann, A.W.; Wijesekera, G.A.S.
Root system of Hevea with special reference to micropropagated plants
(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Seneviratne, P.; Wijesekara, G.A.S.; De Soysa, G.M.
Seed production of clones PB 86, RRIC 100 and RRIC 121 in three rubber growing areas of Sri Lanka
(Rubber Research Institute. Agalawatta, 1997) Seneviratne, P.; Nugawela, A.; Amaratunge, K.A.G.B.; Karunasena, R.P.; Wilbert, S.
The rubber seed production in wet rubber growing areas in Sri Lanka has gone to very low levels in the recent past affecting the culling process that should be adopted in establishing rootstock nurseries.From the three rubber growing areas studied satisfacton seed production irrespective of the clone was observed only in Kegalle region.Regional differences may be due to direct or influences of the climate and weather during flowering and pod set. Clonal differences seems to be existing in regions where climate or the weather is favourable for spread of diseases.Further RRIC 100 being a resistant clone for oidum and phytopthora.produced a higher percemage of good quality seeds compared with the other two clones.PB 86 and RRIC 121 which have below average tolerance to these two diseases.However currently country as a whole produces enough seeds to fulfill country's annual seed requirement for the production of rootstocks provided the seeds are collected and transported without delay