Journal of the Rubber Research Institute of Sri Lanka

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    Effectiveness of coir dust and rubber latex based slow release fertilizer on the growth of immature rubber (Hevea) and soil nutrient availability
    (Rubber Research Institute:Agalawatta, 2017) Hettiarachchi, R.P.; Chandrasiri, J.A.S.; De Silva, K.E.; Edirimanna, V.; Thewarapperuma, A.; Gunathilake, T.; Malawaraarachchi, G.C.; Kulathunge, K.M.M.E.K.; Gayan, M.W.H.; Siriwardana, N.S.
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    Effect of biofilmed biofertilizer on plant growth and nutrient uptake of Hevea brasiliensis nursery plants at field condition
    (Rubber Research Institute:Agalawatta, 2017) Hettiarachchi, R.P.; Seneviratne, G.; Jayakody, A.N.; De Silva, E.; Gunatilake, P.D.T.C.; Edirimanna, V.; Thewarapperuma, A.; Chandrasiri, J.A.S.; Malawaraarachchi, G.C.; Siriwardana, N.S.
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    An analysis of growth patterns of Hevea clones
    (Rubber Research Institute. Agalawatta, 1988) Margret, H.A.W.; Abeyasekera, S.; Jayasekera, N.E.M.
    Four girth measurements collected over four years, before tapping from ten Hevea clones grown in two sites have been analysed to study the growth pattern. Year to year variation in both sites was mainly due t linear component of growth. Growth of individual clones too was mainly due to linear effect. But some clones in one site showed significant quadratic and or cubic component. This was due to non linear growth of plants in some plots. Ten clones have been groued (a) according to the when averaged over four years so that clones within a group have the same average girth and (b) on the gradient of the regression fitted to the girth measurement increasing over the four years. RRIC 52 had the fastest growth in both sites. RRIC 103 had the same growth rates in both sites suggesting that it has a greater stability to local environmental changes.
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    Responses of five tropical pasture species to application of apatite
    (Rubber Research Institute. Agalawatta, 1986) Pathiratne, L.S.S.; Waidyanatha, U.P. De S.; Peries, O. S.
    Shoot growth and phosphorus content of Pueraria, Centrosema, Stylosanthus, Panicum and Paspalum were best at 500ppm and better at 100ppm than at zero ppm apatite. Root growth on the other hand was stimulated at 100ppm and marginally inhibited at 500ppm.Both relative shoot and root growth responses were least for Styl;osanthus which showed a notable ability to take up P from untreated soil compared to the other species. This may be related to its greater calcium uptake ability as evidence d in much higher calcium concentrations in its shoot than in the other. The grasses recovered for more P from both treated and untreated soil than the legumes.
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    On the estimation of leaf areas of some selected Hevea clones
    (Rubber research Institute. Agalawatte, 1984) Wickremasinghe, W.N.; Samaranayake, C.; Abayapala, R.A.P.
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    Effect of vesicular-arbuscular mycorrhizae on seedling of Hevea and Pueraria phaseoloides
    (Rubber research Institute. Agalawatte, 1984) Jayaratne, A.H.R.; Peries, O.S.; Waidyanatha, U.P. De S.
    Hevea seedlings showed a slight growth responce when inculated with Gigaspora margarita out of four species, tested in sterilised soil. There were no significant differences in the uptake of nutrient by mycorrhizal Hevea plants. Non-mycorrhizal Pueraria plants grew very poorly unless they were given liberal quantities of phosphate fertilizer, confirming previous reparts. All mycorrhizal plants took up more nutrients from soil than non-mycorrhizal plants. Effective nodule formation wassignificantly grater in mycorrhizal plants when phosphorus was added.
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    Effect of soil moisture on establishment success of different planting techniques in rubber
    (Rubber Research Institute. Agalawatta, 1993) Samarappuli, L.; Yogaratnam, N.; Hettiarachchi, R.
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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.
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    Performance of some RRIC 100 series clones under different soil moisture regimes
    (Rubber Research Institute. Agalawatta, 1992) Samarappuli, L.; Yogaratnam, N.; Hettiarachchi, R.
    Results obtained on the performance of recently developed RRIC 100 series clones when sujected to water deficit situations are presented in this paper. The plant diameter of RRIC 121 and RRIC 102 was found to be superior to other clones tested such as RRIC 100, RRIC 110 and PB 86 even at the very low soil moisture level of 10% available water. Similar results were recorded in relation to plan height, number of whorls and relative growth rates of clones RRIC 121 and 102 even under low soil moisture conditions. Data obtained also showed that clones RRIC 102 and 121 had the highest plant nitrogen and potassium contents. Moreover, even under very low soil moisture levels plant P content was greater in clones RRIC 121 and 102. Most of the data on growth are also consistat with the physiological parameters such as leaf water protential (LWP) relative water content (RWC), transpiration rate (TR) and leaf diffusive resistance (LDR). It was further noted that the LWP and RWC were highest while TR was lowest in clone RRIC 102. Moreover, the clone RRIC 102 had the highest LDR compared to other clones, confirming the ability of this clone in maintaining a higher water holding capacity under low soil moisture conditions.
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    Towards shorter immaturity and improved yields by mulching with rice straw
    (Rubber Research Institute. Agalawatta, 1992) Samarappuli, L.; Yogaratnam, N.; Samarappuli, P.; Mitrasena, U.
    In this study with immature Hevea brasiliensis, multing with paady straw around the base of the tree was found to be a better agronomic practice than growing leguminous cover crops such as Pueraria phaseoloides and Desmodium ovalifolium or allowing natural vegetation to grow in the inter-row area. Girthing had been much higher with mulching which resulted into reduction of the immature, unproductive period by approximately 18 and 12 month in comparison with naturals and creeping legumes respectively. In addition to early tapping, yield of latex was also higher during the early stages, increases in the region of 33perc. and 40perc. in comparison with creeping legumes and naturals respectively. The present value of the benefit achieved from mulching amount to Rs. 31,088/= per hectare of which Rs. 19,740/= is due to extra yield and the balance of Rs. 11,348/= is saving on inputs as a result of early maturity. Consequently, a net present value (NPV) of Rs. 7.8 million at national level can be achieved with the above practice at 50perc. level of adoption