Rubber Science

MICROFLORA ASSOCIATED WITH PHYLLOPLANE, CAULOPLANE AND RHIZOSPHERE OF TWO POPULAR RUBBER CLONES AT TWO LOCATIONS IN INDIAResearch Articles
Pages 47 - 52
Thomas Mathew & C. Kuruvilla Jacob
- Abstract
- Keywords
Phylloplane, cauloplane and rhizosphere populations of bacteria, fungi, actinomycetes and yeasts associated with the Hevea brasiliensis trees of three age groups (2-3, 5-6 and 10-11 years) and belonging to two popular clones (RRII 105 and PB 260) grown in two locations (Cheruvally and Malankara Estates) in the traditional rubber growing tract of India were evaluated. Bacteria dominated in all the three niches while the population of yeast was the lowest. Rhizosphere harboured the highest and cauloplane the lowest number of microorganisms. There was no significant variation in microflora between the two clones. In general, there was an increase in microbial population with the age of the plantation but with respect to the location there was no general trend. The availability of plant exudates appears to influence the association of microflora on the plant surfaces.

Age, Cauloplane, Clone, Hevea brasiliensis, Microflora, Phylloplane, Rhizosphere

EFFECT OF HUMIDITY AND TEMPERATURE ON DRYING OF NATURAL RUBBERResearch Articles
Pages 53 - 59
Siby Varghese, Treesa Cherian & Baby Kuriakose
- Abstract
- Keywords
The effect of temperature and relative humidity on drying of three forms of natural rubber viz., rolled latex coagulum, latex coagulum crumb and field coagulum crumb was studied by recording the percentage reduction in moisture content with time. Influence of the surface area on drying was demonstrated using yeast treated latex coagulum. Results indicated that larger portion of the drying time was for the second phase of drying (below 10% moisture), which involves diffusion of moisture from the coagulum. The rate of diffusion is influenced more by temperature of drying than by relative humidity.

Diffusion, Drying, Moisture content, Natural rubber, Relative humidity, Sheet rubber.

CLONAL NURSERY EVALUATION FOR SHORTENING THE BREEDING CYCLE IN HEVEA BRASILIENSISResearch Articles
Pages 60 - 66
Kavitha K. Mydin, J. Licy, Y. Annamma Varghese, Alice John, Ramesh B. Nair & C.K. Saraswathyamma
- Abstract
- Keywords
Twenty two hybrid clones of rubber (Hevea brasiliensis Muell. Arg.) evolved at the Rubber Research Institute of India were evaluated for growth and dry rubber yield in a clonal nursery and in the main field in small-scale trials. Clones with good yield and stable performance in the nursery were selected by a rank-sum method. Juvenile-mature correlations were worked out in an attempt to study the prospects of reducing the time span of clonal selection. Significant positive correlation between juvenile yield in the clonal nursery and initial yield at maturity suggested scope for preliminary evaluation of clones in a nursery.

Clonal nursery, Early selection, Girth, Hevea brasiliensis, Juvenile-mature correlations, Rank-sum, Yield

EFFECT OF CONTROLLED RELEASE FERTILIZERS ON GROWTH AND LEAF NITROGEN STATUS OF IMMATURE RUBBERResearch Articles
Pages 67 - 73
Sherin George, Valsa George, M.D. Jess & K.I. Punnoose
- Abstract
- Keywords
The growth and leaf nitrogen status of immature rubber (Hevea brasiliensis) trees (clone RRII 105) which received 50 or 75 per cent of the recommended dose of N as NPK Mg tablets or 75 per cent as neem extract coated or neem cake mixed urea were comparable to those which received the full dose as prilled urea in two field experiments conducted in the central region of the traditional rubber growing tract of India, during 1994 to 1998. Single low dose of N applied as NPK Mg tablets was comparable to split doses of other fertilizers in terms of growth (girth) of the plants.

Controlled release fertilizers, Growth, Hevea brasiliensis, Leaf nitrogen, Immature rubber

EVALUATION OF HEVEA BRASILIENSIS CLONES AGAINST ABNORMAL LEAF FALL DISEASE CAUSED BY PHYTOPHTHORA SPP.Research Articles
Pages 74 - 78
Sadanand K. Mushrif, Annakutty Joseph, Alice John & C. Kuruvilla Jacob
- Abstract
- Keywords
Twenty five modern clones of rubber (Hevea brasiliensis) were evaluated for tolerance to abnormal leaf fall disease caused by Phytophthora spp., consecutively for seven years under standard prophylactic spray. Two trials each consisting of 13 clones were included in the evaluation. High leaf retention was noticed in the clone RRII 105 closely followed by RRII 5 while it was poor in RRIM 703, RRIM 600, Haiken 1, PB 280, PB 260 and PB 314. Rainfall was found to be a major predisposing factor influencing the disease development

Abnormal leaf fall. Hevea brasiliensis, Clone evaluation, Phytopbthora

REDUCED MEMBRANE DAMAGE AND HIGHER LEA PROTEIN CONTENT UNDER LOW TEMPERAURE: PROBABLE CAUSES FOR DELAYED DEFOLIATION OF HEVEA IN NORTH EAST INDIAResearch Articles
Pages 79 - 85
Debabrata Ray, Shammi Raj, Gitali Das & S.K. Dey
- Abstract
- Keywords
Two popular clones of Hevea brasiliensis were studied to understand their defoliation pattern in relation to some of the biochemical parameters during the winter season. The low temperature induced changes such as membrane injury, anthocyanin and late embryogenesis abundant (LEA) protein accumulation were examined. The early defoliating clone RRII 105 showed high membrane injury, anthocyanin accumulation and rapid chlorophyll degradation with low LEA protein, whereas the late defoliating clone RRIM 600, recorded the opposite trend. It can be inferred that the temporal difference in wintering and in the biochemical parameters studied are related to cold susceptibility.

Anthocyanin, Chlorophyll, Defoliation, Hevea brasiliensis, LEA protein, Membrane damage, Wintering