Latex vessels form a very imperative tissue system in the secondary phloem of Hevea brasiliensis. They run in the longitudinal axis of the stem with a specific angle of inclination for a particular Hevea clone. Rubber particles are synthesized in the laticiferous system present in the bark tissue and exploited through controlled wounding of the bark called tapping. Most of the laticifer characters have great significance for latex yield in Hevea. A detailed investigation on the latex vessel characters of ten clones has been made in the present study. The secondary phloem consisted of soft bark (SB) region devoid of stone cells and inner hard bark (IHB) region with stone cells. Number of latex vessel rows in both the location was higher in PB clones. The distance between laticifer rows exhibited significant clonal variability. About 90 per cent of the latex vessels were running contiguous to phloic rays and only 10 per cent remained non-contiguous to phloic rays. The articulated and anastomosing nature of laticifers were well supported by inter-connections and it was the highest in the clone RRII 105. Significant superiority of PB clones with respect to latex vessel diameter and total cross sectional area of laticifers was also noticed.

The study confined to the smallholdings, which availed planting subsidy during 2004-10, showed that among the various intercrops, banana was the most popular intercrop in the traditional rubber growing region which spread over five agro-climatic zones. The results of the study revealed that there were notable differences in the extent of adoption of intercropping, choice of crops and size-class-wise preferences. The highest level of adoption of intercrops in rubber plantations was observed in Kanyakumari region (72.8%) followed by Central Kerala (72.2%) and South Kerala (68.2%) during the seven year period under study. Adoption of intercrops was the lowest in North Kerala (36.2%). The analysis revealed that pineapple replaced banana as the choicest intercrop in Central Kerala. The size of holding was a key determinant in the selection of intercrops. A positive relationship was observed between large size of holding and adoption of commercial crops such as banana and pineapple whereas subsistence crops such as tapioca, amorphophallus and colocasia were preferred in the smallest size-class.

Historically, price movements of all forms of natural rubber in India have been either directly or indirectly linked to the trends in the price of the dominant RSS 4 grade. Under the protected price policy regime, the prevailing interlinkages among the prices have ensured comparative stability and margins at various stages. The price movements of all forms of processed/unprocessed rubber including preserved field latex (PFL) and centrifuged latex (CL) have also been based on the price movements of RSS 4. However, instability in the RSS 4 prices consequent to the trade policy reforms since the early 1990s led to important structural adjustments in the domestic market. As a survival strategy, the latex processing industry has gradually delinked PFL price from RSS 4 and linked to CL price in order to protect the margins since the mid 2000s. The preliminary observations of the study highlighted the crucial role of the growing narrowness of the domestic market due to the significant growth in the import of latex based value added products rather than the import of CL for the segmentation of the latex market. Hence, a two pronged strategy of rehabilitating the latex based manufacturing segment so as to ensure commensurate rate of growth in latex consumption and rejuvenating the latex processing industry to reinforce the focus on exports is suggested.

A field survey was conducted on 14,720 rubber trees in 32 ha clonal garden of Rubber Research Institute of Nigeria (RRIN) in July- September 2011, to evaluate the status of new root diseases by visual examination. The infection of red root rot was 0.02 per cent. Two varieties of red root rot were encountered; large one that caused infection on living rubber tree termed ‘infective red root rot’ and the second seen only on dead rubber trunk and subterranean or on dead rubber stumps already killed by white root rot termed as ‘non-infective’ red root rot. The size of the fruiting bodies of the ‘infective red root rot’ ranged from 27-30 cm by 17.5-19 cm (length x breath) with shinning dark red upper surface with narrow white margin and ash-light-yellow under surface and a prominent creamy-white fringe. The size of the ‘non-infective’ fructification ranged from 5.3 to 5.7 cm by 3.1 to 4.2 cm (length x breath) with dark brownish red upper surface and wide white margin and white under surface and a prominent creamy-white fringe. This study confirms the incidence of red root disease in rubber plantations in Nigeria and report the existence of two varieties of Ganoderma psuedoferreum. The study also suggests further regular field inspection of plantations and adequate control measures to forestall epidemic outbreak of the pathogen in plantations in Nigeria.

Recent developments in polymer blends and composites from non-polar/polar rubbers are reviewed in this article. Blending of elastomers is frequently used to enhance the performance/processing characteristics of rubber compounds. Many of the elastomer blends are characterized by a two-phase morphology, narrow interface, and poor physical and chemical interactions across the phase boundaries resulting in poor mechanical properties. To overcome this, compatibilizers and reactive blending are generally used which improve the interfacial adhesion and reduce the coalescence between non-polar/polar rubbers. These blend systems are immiscible and the compounding ingredients are nonuniformly distributed in two phases depending on their affinity, rate of diffusion and reactivity to different components.

Fresh natural rubber (NR) latex coagulates immediately by sensitization with suitable surfactants. When surfactants are added to latex, the surfactant anions displace a part of protein molecules and get adsorbed on the rubber particles. The surfactants retained on rubber during coagulation play a major role on the cure characteristics, mechanical properties and ageing characteristics of the recovered rubber. Better cure characteristics as revealed from a higher level of vulcanization are obtained for gum and carbon black filled compounds for NR prepared by immediate coagulation in comparison with the conventionally coagulated NR. Better mechanical properties and solvent ageing resistance are also observed. Carbon black filled vulcanizates give a higher modulus, tensile strength, hardness and significantly higher abrasion resistance as compared with conventional rubber vulcanizate. The compression set and heat build-up characteristics are comparable. The improvement in mechanical properties and solvent resistance obtained for the NR prepared by the new process is attributed to the surfactants retained in rubber, higher level of vulcanization and better dispersion of filler.