Rubber Science

RESEARCH ON SOUTH AMERICAN LEAF BLIGHT (MICROCYCLUS ULEI) OF RUBBER IN BRAZILResearch Articles
Pages 83 - 90
L. Gasparotto & M. I. P.M. Lima
- Abstract
- Keywords
South American leaf blight (SALB), caused by Microcyclus ulei, remains a problem of overriding importance in rubber (Hevea brasiliensis) cultivation in Brazil. The disease is widely distributed and is responsible for poor latex yield. Research on this disease is concentrated on epidemiology, development of resistance, disease avoidance mechanisms and chemical control.

Hevea brasiliensis, South American leaf blight, Microcyclus ulei, Brazil

EFFECT OF ETHEPHON ON BARK WOUND HEALING IN HEVEA BRASILIENSISResearch Articles
Pages 91 – 96
Jilin Wu & Bingzhong Hao
- Abstract
- Keywords
Wound healing of ethephon-treated and untreated bark of Hevea brasiliensis was studied using microscopy. Cell wall lignification of wound margin appears earlier and more lignified cells occur in treated bark. The first cell divisions leading to the formation of callus and wound periderm are postponed by ethephon treatment. The sequent periderm is formed beneath the first periderm around the wound of ethephon-treated bark, while no such periderm occurs in untreated bark. The significance of the results is discussed in relation to the ethephon-induced resistance of Hevea bark to black stripe, a wound disease.

Hevea brasiliensis, Wound healing, Ethephon, China

CHARACTERISATION AND TREATMENT OF WASTE WATER FROM A CENTRIFUGE RUBBER LATEX CONCENTRATION UNITResearch Articles
Pages 97 - 102
G. Madhu, K. E. George & D. Joseph Francis
- Abstract
- Keywords
Characterisation of the waste water from a centrifugal latex concentration unit was carried out. Conventional coagulants were tried to remove turbidity and chemical oxygen demand (COD) of the waste water. Aluminium chloride was found to be the best for the removal of both turbidity and COD.

Natural rubber, Waste water, Centrifugal latex concentration, Turbidity, COD, Coagulants, Effluent treatment

NURSERY EVALUATION OF HEVEA GENOTYPES OF THE AMAZON BASINResearch Articles
Pages 103 - 106
K. O. Omokhafe
- Abstract
- Keywords
Genotypes obtained from the IRRDB sponsored Hevea prospection mission were evaluated for nursery characters at the Rubber Research Institute of Nigeria in February, 1990. Scion height and stem diameter had high coefficients of variation of 33 and 31 per cent respectively and they were found to be adequate for estimating genetic variability in Hevea. High genetic variability and correlations were obtained in this study. The entire collection from the Amazon basin is therefore promising for future breeding work.

Hevea brasiliensis, Genetic variability, Amazon basin, Nigeria

GROWTH, YIELD AND FLOW CHARACTERS AND THEIR CORRELATIONS WITH BROWN BAST INCIDENCE IN TEN HEVEA CLONESResearch Articles
Pages 107 - 113
D. Premakumari, A. O. N. Panikkar, M. R. Sethuraj & Joseph G. Marattukalam
- Abstract
- Keywords
Ten popular clones were evaluated for growth, latex flow characters, yield and brown bast incidence. Clones differed for initial rate of flow, duration of flow, plugging index, dry rubber content, girth, total volume of latex and dry rubber yield. Girth increment on tapping and incidence of brown bast were not statistically significant. Brown bast incidence was positively correlated with total volume of latex and dry rubber yield. Positive relationships of this trait with initial rate of flow, duration of flow and dry rubber content and its negative relationships with girth increment on tapping and plugging index were not significant. It was indicated that high latex volume at the initial years of tapping contributed to occurrence of brown bast during subsequent years. Among medium to low yielding clones more interference of other factors was apparent.

Hevea brasiliensis, Dry rubber content, Brown bast, Latex flow, Yield

PRELIMINARY STUDIES ON THE PREPARATION OF RUBBER SEED OIL ALKYDSResearch Articles
Pages 114 - 117
A. I. Aigbodion
- Abstract
- Keywords
Three samples of alkyd resins having 45, 52 and 62 per cent of oil were prepared using phthalic anhydride, glycerol and rubber seed oil extracted by a screw press. Progress of the reaction was followed by measurement of the acid value of the reaction mixture at 30 min intervals. The monoglyceride formed did not make a clear solution in methanol (1:3) due to presence of impurities in the oil and the dark colour of the oil resulted in the formation of dark coloured alkyds. Extents of esterification calculated at the time when there was a sharp decrease in acid value were 69.92, 77.82 and 61.48 per cent for the three samples. The calculated degrees of polymerization indicated formation of appreciable high molecular weight resins. The finished alkyds were soluble in xylene (3:2 dilution). The resins were of good quality, but their properties varied with the oil content.

Rubber seed oil, Alkyd resins, Gelation