Rubber Science

MANAGEMENT OF SLUGS AND SNAILS ON YOUNG RUBBERResearch Articles
Pages 32 - 35
V.T. Jose, C.R. Nehru & K. Jayarathnam
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- Keywords
Aldicarb granules and Snailkill (2.5% metaldehyde) applied as broadcast (20 g/plant) and aldicarb 0.01 per cent slurry with maida proved to be molluscicidal when applied to young rubber plants. Bordeaux paste showed repellent activity for 45 days.

Hevea, Mariaella dussumieri, Cryptozona bistrialis, Slugs, Snails, Molluscicides

SUITABILITY AND ECONOMIC VIABILITY OF INTERCROPPING IN RUBBER ON ACID SANDY SOIL OF SOUTHERN NIGERIAResearch Articles
Pages 36 - 39
T.U. Esekhade, I.K. Ugwa & E.O. Aigbekaen
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- Keywords
Results from field experiments on intercropping of cassava, cowpea and melon with rubber in sandy acidic (4.0- 4.6 pH) soil at Akwete Abia State, Nigeria showed that there was adverse effect on the girth and height of rubber plants. The rate of girth increase for rubber was from 0.19 to 0.21 cm/month. The nitrogen contents of the soils increased after intercropping. The rubber+ cassava combination gave the highest yield of 6.5 t/ha and a net present value of 2,431 naira and an internal rate of return of 29 per cent, followed by the rubber + cassava + cowpea + melon combination with a yield of 3.8 t/ha, a net present value of 816 naira and an internal rate of return of 29 per cent.

Hevea brasiliensis, Intercropping, Soil properties, Nigeria

ESTIMATION OF BIOMASS IN HEVEA CLONES BY REGRESSION METHOD : 2. RELATION OF GIRTH AND BIOMASS FOR MATURE TREES OF CLONE RRIM 600Research Articles
Pages 40 - 43
S.K. Dey, D. Chaudhuri, K.K. Vinod, Jacob Pothen & M. R. Sethuraj
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Determination of biomass in tree crops like Hevea is cumbersome and a most viable alternative method is to estimate the biomass as a function of a common measure of growth, like girth. In the present study relationships were worked out with girth at 150 cm from bud union and above ground biomass for trees of clone RRIM 600. Both power as well as exponential regression equations fitted were found to be reliable in all classes of girth from 45 to 93 cm. The relationships are W =0.0202 G^2.249 (power) and W = 24.8486 e^0.0343G(exponential).

Hevea brasiliensis, girth, biomass, regression

PERFORMANCE ANALYSIS FOR WINTERING PATTERN IN HEVEA BRASILIENSIS CLONESResearch Articles
Pages 44 - 47
K.K. Vinod, J. Rajeswari Meenattoor, Jacob Pothen, A.K. Krishnakumar & M. R. Sethuraj
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A study was undertaken to group rubber (Hevea brasiliensis) clones based on their wintering behaviour in Tripura, one of the rubber growing areas of North East India. Fifteen clones from a clone evaluation trial were scored for the wintering pattern at weekly intervals for six weeks from December to February during 1988-89, 1989-90 and 1991-92 period. Wintering pattern of clones was uniform for all the years under study. Mean weekly scores were used for clustering process. Three distinct clusters of early, intermediate and late wintering clones were obtained viz., (i) RRII 105 and RRIC 105, (ii) RRIM 600, PB 86, GT 1, RRIC 52 and PB 235 and (iii) RRII 118, RRIM 605, Gl 1, Harbel 1, RRII 5, PB 5/51 and RRIM 703. The remaining clone, RRII 203, was found to fall in between the second and the third clusters. The results can be used in characterising clones as well as selecting clones for establishing polyclonal breeding gardens.

Hevea brasiliensis, Wintering, Cluster analysis , Tripura

VARIATION IN MINERAL COMPOSITION OF LEAVES AND ITS RELATIONSHIP WITH PHOTOSYNTHESIS AND TRANSPIRATION IN POLYCLONAL SEEDLINGS OF HEVEA BRASILIENSISResearch Articles
Pages 48 - 54
P.Sobhana, S.K.Dey, Elsie S.George, James Jacob & M.R. Sethuraj
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Polyclonal seedlings of Hevea brasiliensis were examined for differences in major nutrient contents of leaves, photosynthetic CO₂ exchange rate (CER) and associated characteristics and biomass production. In spite of the application of equal doses of N, P and K to all the plants, considerable variations were observed in leaf N, P and K contents indicating the genotypic variation in absorption of mineral nutrients. Leaf N,P and K per unit leaf area exhibited significant positive correlations with CER, stomatal conductance (gs) and transpiration rate. Leaf nutrient content showed positive relationship with the instantaneous water use efficiency of leaves. Leaves of the polyclonal seedlings also showed appreciable variation in mineral composition, photosynthetic rate and water use efficiency.

Hevea brasiliensis, Shoot biomass, Transpiration, Water use efficiency

OCCURRENCE OF GLOEOSPORIUM ALBORUBRUM ON RUBBER IN MEGHALAYAShort Scientific Reports
Pages 55 - 57
H. K. Deka, A. P. Thapliyal, G.C. Mandal, R.R. Sinha & M.R. Sethuraj
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