RRI Publications
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Item A rapid minipreparation method for DNA extraction from Hevea leaf tissue(Rubber Research Institute. Agalawatte, 1996) Herath, S.; Attanayaka, D.P.S.T.G.; Karunanayake, E.H.Use of DNA markers in plant breeding is increasingly becoming popular. A basic requirement in using this technique in plant breeding is the availability of a simple inexpensive method for the isolation of plant DNA from large populations. Here we describe a rapid method of DNA isolation from Hevea leaf tissue. DNA yields obtained by this method were comparable with the yields of the other available methods. The quality of the DNA was tested by digesting with several restriction enzymes and was found to be of adequate purity. Southern blot analysis of this DNA showed its suitability for RFLP analysis of Hevea.Item Role of potassium on growth and water relations of rubber plants(Rubber Research Institute. Agalawatta, 1993) Samarappuli, L.; Yogaratnam, N.; Karunadasa, P.; Mitrasena, U.; Hettiarachchi, R.Item Some effects of isolates of Trichoderma on Rigidipourus lignosus(Rubber Research Institute. Agalawatta, 1991) Wijesundara, R.L.C.; Jeyanathan, S.; Liyanage, N.I.S.Seven forms of Tricoderma were isolated from soil obtained from rubber plantations. All the isolates secreted compounds inhibitory to the growth of Rigidiporus lignosus the causal agent of the white root disease of rubber. Further, the Trichoderma isolates interacted with the hypase of R. lignosus, the interaction resulting in harmfull effects on R. lignosus hyphae. Of the isolates examined T. Koningii isolate IV and T. harzianum appear to be very promising as potential biocontrol agentsItem The positional effect of the explant on In vitro growth of axillary buds of Hevea brasiliensis(Rubber Research Institute. Agalawatte, 1996) Senaviratne, P.; Flegmann, A.W.; Wijesekera, G.A.S.Apart from the high apical dominance showed in shoot explants of hevea, the location of the node in the shoot, seems to play a vital role in in vitro axillary bud proliferation. Better performance was observed when the axillary buds harvested as nodes, were not too close and also not too far from the apex as measured by the primary axillary shoot growth. This was true for both juvenile and mature arigin materials. Furthermore, "active" nodes were superior to "dormant" nodes.Item 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.Item Somatic embryogenesis for hevea. the technique of anther culture(Rubber Research Institute. Agalawatte, 1996)Production of pollen plants via somatic embryogenesis might be cultivar dependant as successful production of pollen plants is reported only by chinese scientists. None of the locally available clones of hevea produced even somatic embryos. The slow progress made on adoptation of this technique suggests difficulties in reproducing, may be due to various critical factors involved in the process. The rate of callus formation was influenced by the amount of auxins an d cytokinins in the medium and the presence of both types was important for initiation of callus.Item 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.Item Diurnal variation in gas exchange characters of leaves of Hevea brasiliensis exposed to sun light at different canopy levels and their contribution to dry matter production(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Nugawela, A.; Abeysinghe, D.C.A.; Samarasekera, R.K.As in many other crops a significant percentage of leaves in the canopy of a rubber plantation are found under limiting light levels. The photosynthetic capacity of these shaded leaves may play an important role in determining the productivity of the rubber plants. The dry matter production capacity of shade leaves was srudied using polybag plants of Hevea brasiliensis and grown under different light regimes. The CO2 assimilation rates and related parameters were monitored through-out the day using a portable photosynthesis system. The diurnal variation pattern of CO2 assimilation rates and the internal leaf CO2 concentration to ambient CO2 concentration ratio (ci/ca) were different in plants grown under different light regimes. Though peak CO2 assimilation rates are shown at around 0930h in all treatments, the assimilation rates tend to decline very early in plants grown under full light. During the early and latter parts of the day, plants grown under full light showed significantly higher CO2 assimilation rates than in plants grown under 40 per cent and 25 per cent of incident light. However, stomatal conductance declined with time of the day and it was similar in all treatments. Low CO2 assimilation rates later in the day could be either due to accumulation of abscisic acid or due to end product inhibition. It is apparent that photosynthesis is only marginally high during the major part of the day, ie 0930h - 1430h in plants grown in full light. Therfore, sun and shde leves may be comparable as the daily photosynthetic integral and hence the dry matter production is concerned. Thus, shaded leaves in rubber plantations may significantly contribute to the total dry matter production of the plant.Item In vitro interactions between Rigidoporus lignosus, the case of white root disease of rubber and some potentially antagonistic fungi(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Jayasuriya, K.E.; Deacon, J.W.The modes of aaction of fungi potentially antagonistic against R. lignosus were assessed in vitro by studying their ability (a)to cause pre- or post-contact damage to R. lignosus hyphae in video taped interactions on thin purified water agar films and, (b) to displace the established pathogen from woody inocula. The most fungi were Trichoderma spp. which produced volatile or non-volatile inhibitors. Basidiomycetes such as Trametes sp. caused hyphal interface similar to that of Phlebiopsis gigantea, a commercial biocontrol agent of Heterobasidion annosum in pine stumps. species of Trametes and Aspergillus partially or completely displaced R. lignosus from previousley colonized woody inocula.Item The role of snag on the growth of scion in bud grafted plants of Hevea with special reference to young buddings(Rubber Research Institute of Sri Lanka. Agalawatte, 1995) Senaviratne, P.; Nugawela, A.; Samarakoon, S.M.A.