Rubber Science

SEASONAL VARIATION IN MICROFLORA OF RUBBER GROWING SOILS OF MEGHALAYAResearch Articles
Pages 151 - 154
H. K. Deka, A. P. Thapaliyal, R. R. Sinha, S. N. Potty & M. R. Sethuraj
- Abstract
- Keywords
A study on the seasonal variation of microflora in five rubber growing soils has been carried out. The population of fungi bacteria and actinomycetes varied greatly in different soil samples. The total population of bacteria and antinomycetes was found to be more than that of fungi. Statistically, a significant positive correlation was found between the number of microorganisms and soil moisture status as well as pH. Qualitatively, not much variation was observed in the composition of fungal species, and only a few fungi were recorded with a high percentage of relative abundance. Apparently, the different soils and seasons did not seem to exert any influence on the fungal species composition.

Hevea brasiliensis, Seasonal variation, Soil microflora, Non-traditional area, India

QUANTIFICATION OF RUBBER AND RESIN IN GUAYULEResearch Articles
Pages 155 - 160
Nipun Marwah, Asha Masohan & Virendra K. Bhatia
- Abstract
- Keywords
A method for the quantification of rubber and resin in guayule involving extraction with hexane followed by acetone has been standardised. The accuracy of the method has been compared with the one using these solvents in the reverse order. Results on the effect of the sequence in which the two solvents are used on the quality and quantity of rubber and resin are presented.

Rubber, Resin, Guayule

POLYMORPHIC ISOZYME EXPRESSION CAUSED BY STOCK SCION INTERACTION IN HEVEA BRASILIENSIS CLONE RRII 105Research Articles
Pages 161 - 171
R. Krishnakumar, M. P. Asokan & M. R. Sethuraj
- Abstract
- Keywords
Isoelectric focusing (IEF) was used for finger printing five different isozymes from the leaf extracts of 22 individual budded Hevea plants (clone RRII 105) to study the enzyme polymorphism due to stock-scion interaction. The results showed remarkable variations in the isozymic banding patterns of aspartate aminotransferase (AAT), leucine aminopeptidase (LAP), acid phosphatase (ACP), alkaline phosphatase (ALP) and phosphogluco isomerase (PGI) isozymes which have vital roles in several plant metabolic pathways. The variations noticed in the isozyme patterns among the budded plants of the same clone may be due to the stock scion interaction.

Hevea brasiliensis, Isoelectric focusing, Isozymes, Stock-scion interaction, Enzyme polymorphism

RESPONSE OF SOME HEVEA CLONES TO PERIODIC TAPPING SYSTEMSResearch Articles
Pages 172 - 178
Kuswanhadi, Untung Djunaidi, Amin Tjasadihardja & Thomas
- Abstract
- Keywords
The objective of this experiment was to study the response of recommended Hevea clones in Indonesia to periodic tapping systems. Cumulative yield for 5 years of tapping of periodic tapping systems (1/2S d/1 5d/7 2m/3 and 1/2S d/1 6d/7 m/2) were comparable with the conventional system of GT 1; but lower for PR 300 and AVROS 2037, and higher for RRIM 600. For PR 261, only 1/2S d/1 5d/7 2m/3 resulted in a higher yield. Girth increment was slightly retarded in periodic systems, especially for PR 300. Growth of renewed bark was not affected, but dry rubber content of latex was slightly lowered. Intensity of dry bark incidence depended on clonal susceptibility. PR 261 seemed to be prone to bark dryness. Periodic tapping systems could be recommended as alternatives to the conventional system for the clones GT 1 and RRIM 600. RRIM 600 showed the best response to periodic systems.

Hevea, Periodic tapping system, Indonesia

IN SITU EPOXIDATION OF NATURAL RUBBER LATEX BY PERFORMIC ACID AND THE KINETICS OF THE REACTIONResearch Articles
Pages 179 -187
Benny George, Shiny Abraham & N. M. Mathew
- Abstract
- Keywords
Epoxidation of natural rubber latex stabilised with a nonionic surfactant was carried out with performic acid generated in situ. The reaction was performed at 30, 40, 50 and 60°C at a dry rubber content (DRC) of 20 and concentration of formic acid and hydrogen peroxide 0.955 and 3.75 moles dm^-3 respectively in the aqueous phase of the latex.. Product characterization by ¹H NMR and IR spectroscopic methods indicated significant influence of temperature on the extent of epoxidation as well as ring opening reactions. Epoxidation to the extent of 25-35 mole per cent could be reached without ring opening. The concentration of ring opened products at higher levels of epoxidation was found to be low. The reaction followed psuedo-first order kinetics with the formation of performic acid as the rate determining step. This was further confirmed by carrying out the reaction at 10 and 15 per cent DRC keeping the formic acid and hydrogen peroxide concentrations in the aqueous phase the same.

Natural rubber latex, Epoxidation, Performic acid, Epoxidation kinetics, Ring opening reactions

DIFFUSION AND ADOPTION OF INNOVATIONS IN RUBBER SMALLHOLDINGSResearch Articles
Pages 188 - 194
P. Rajasekharan & V. Haridasan
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- Keywords
The study, conducted during 1990 covering 480 smallgrowers in Kottayarn district, revealed that 97 per cent of the sample growers planted the clone RRII 105. Among them, 26 per cent did not spray fungicides for the control of abnormal leaf fall disease. Forty six per cent of the growers were found to adopt daily tapping of trees. The percentage of growers who depended on other growers for various technical knowledge ranged from 22 tp 35. The promotion of technological dualism and a resource based classification of growers were suggested for the effective transfer of technology.

Natural rubber, Profitability, Technology transfer