Rubber Science

AGEING OF MATURE AREA AND DECLINING YIELD PROFILE OF NATURAL RUBBER IN INDIAResearch Articles
Pages 109 - 118
Jom Jacob & K. Tharian George
- Abstract
- Keywords
The paper is focused on the trends in age-composition of mature area under natural rubber cultivation in India from a long-term policy perspective. The analysis is based on official data pertaining to historical planting of natural rubber and commercial yield profile of the clone RRII 105 during its life cycle. The results highlighted a steady growth in area under the yield declining phase and the resultant downward trends in estimated average crop yield since 2001-02. The projected share of area under the yield declining phase is 46 per cent and the projected average yield is 1593 kg/ha for the year 2014-15. Since the estimated average yield and production since 2001-02 are at variance with the official data, there is need for a reliable database on the age-composition of area under rubber for long term policy interventions.

Age-composition, Hevea brasiliensis, India, Mature rubber plantation, Yield projections, Yielding phases

BIODIVERSITY OF EARTHWORMS IN THE SOILS UNDER RUBBER PLANTATIONS IN TRIPURAResearch Articles
Pages 119 - 124
P. S. Chaudhuri, S. Nath, S. Bhattacharjee & P. Chakraborti
- Abstract
- Keywords
In spite of the monoculture nature of the plantations, rubber (Hevea brasiliensis) plants offer an ecofriendly environment for soil flora and fauna. The dense canopy of the rubber plants provides shade and conserves soil moisture. This makes the soil hospitable to soil microarthropods and earthworms which play a major role in soil fertility, ecosystem function and production. Rubber plantations in Tripura showed the presence of 20 species of earth worms. Interestingly, rubber plantations show high indices of dominance and low species diversity of earthworms and soil microarthropods as compared to that of the mixed forest. Being an exotic earthworm with its origin in Brazil, Pontoscolex corethrurus represents 61 per cent biomass and 72 per cent density of total earthworm population in the rubber plantation

Biodiversity, Earthworms, Microarthropods, Monoculture, Nematodes, Rubber

PERFORMANCE OF SURFACE MODIFIED CLAYS IN NATURAL RUBBER COMPOUNDSResearch Articles
Pages 125 - 129
Leelamma Varghese, K.N. Madhusoodanan, K.T. Thomas & N.M. Mathew
- Abstract
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Natural rubber compounds containing different modified clays were evaluated for their processing and technological properties. The amino and mercapto silane modified compounds had higher modulus and abrasion resistance and lower compression set. Flex cracking resistance was more when mercapto silane modified filler was used and hence this was rated as superior modification for clay to be used in natural rubber compounds.

Fillers, Natural rubber compounds, Modified clay

INOSITOLS: A COMMERCIALLY IMPORTANT SUGAR ALCOHOL FROM NATURAL RUBBER LATEXResearch Articles
Pages 130 - 133
Jayasree Gopalakrishnan, Molly Thomas & James Jacob
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Besides rubber (cis-I, 4-poly isoprene), latex from Hevea brasiliensis is a rich repository of several important secondary metabolites. Among these inositols, particularly L- quebrachitol is the major group of sugar alcohol which has wide applications in pharmaceutical and medical research. In the present study, total inositol content in thirteen Hevea clones was determined. Inositol content was comparatively high in the clones RRII 105, RRII 5 and RRIM 703. The possibility of commercial exploitation of this high value secondary metabolite is being explored.

Inositols, L- quebrachitol, Natural rubber latex, Secondary metabolites

EFFECT OF RUBBER ON INTERCROPPED TEA DURING IMMATURE PHASE OF RUBBER CULTIVATIONResearch Articles
Pages 134 - 138
Gitali Das, Rama Shankar Singh, Tankeswar Gohain, Shankar Meti, D. Chaudhuri & M.A. Nazeer
- Abstract
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An experiment was conducted to assess the eco-physiological sustainability of growing tea as an intercrop in rubber in the Dooars area of West Bengal and to identify the optimum spacing for both the crops. Four different combinations of rubber interplanted with tea, along with pure rubber and tea as controls were considered. Results proved that growth of rubber was better under intercropped plots than pure crop. Girthing of rubber (5 x 5 m, one row) intercropped with tea (1 x 0.6 m, 10 rows) was significantly higher than that in the pure rubber stand (5 x 5 m). Higher girth of tea was observed in pure crop stand (1 x 0.6 m) followed by paired rows (18m x 3x3) interplanted with tea (1 x 0.6m, 18 rows). Yield of green tea leaf was found to be higher in pure tea stand than in the other treatments. The remunerative index worked out for up to sixth year of planting indicated the beneficial effect of rubber intercropped with tea.

Girth, Intercropping, Rubber, Tea, Yield

P- PROTEIN IN THE SIEVE ELEMENTS OF HEVEA BRASILIENSIS TREES AFFECTED BY TAPPING PANEL DRYNESSResearch Articles
Pages 139 - 144
S. Pramod, Vinoth Thomas & K.S. Rao
- Abstract
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The structural features of P-proteins in the sieve elements of Hevea brasiliensis were studied in relation to Tapping Panel Dryness (TPD) and stimulation of affected bark with ethephon and vitex (a proprietary chemical formulation). The P-protein appears as a narrow, elongated structure in the sieve plate of healthy trees and unaffected parts of TPD affected trees whereas the TPD affected area of trees on rest for three years showed thick P-protein plugs. When the affected bark of TPD trees on rest were treated with ethylene the P-protein present in the active sieve element disappeared, while stimulation with vitex resulted in a positional change in P-protein. Callose deposition that followed in such stimulated sieve elements led to their senescence. The sieve element plugging that regulate photosynthate translocation with reference to TPD is discussed.

Hevea brasiliensis, P-protein, Sieve element, Stimulation, Tapping Panel Dryness