Natural rubber is obtained commercially from Hevea brasiliensis by the process of controlled wounding called tapping. Optimising tapping systems with appropriate dose and frequency of ethephon application can be one of the approaches to address shortage of skilled tappers and can help in realising potential yield from rubber trees. In the present scenario, yield stimulation technology has been perfected and advocated to get promising yield under lower frequencies of tapping, from mini cuts or from punctures with gaseous / ethephon stimulation. An experiment with vertical tapping cuts of 22 and 10 cm cut lengths with different levels of yield stimulation with 2.5 per cent ethephon was conducted for four years to examine the scope and feasibility of vertical tapping as a latex harvest technology tool for crop extraction of mature rubber trees of clone RRII 105. Initial results from the study indicated promise of adoption of vertical tapping of 22 cm (with ET 2.5 % 12 or 24 rounds per year) or 10 cm (with ET 2.5 % 24 or 36 rounds per year) with yield level at par with standard recommended crop harvesting practice (S/2 d3 6d7 ET 2.5% 3 rounds per year) without deleterious effect.  The system is also having the additional advantage of tapping one panel for two years unlike in half spiral downward tapping panel marked for one year which can be tapped only for a year.

Twelve monoclonal blocks comprising pipeline clones and popular clones were evaluated. Early growth parameters were recorded when the trees were three years old.  In the 12 blocks evaluated, P 70, and RRII 429 recorded the highest girth (24.0 cm each) and the highest stem volume (0.01m3 each). RRII 414 and RRII 417 recorded the second highest girth (23.0 cm each) followed by pipeline clones P 21 and P 26 (22.0 cm each). Stem volume was 0.009 m3 each in RRII 414 and RRII 417 followed by P 21, P 26, RRII 422 and PB 330 (0.008m3 each). Girth of RRII 105, RRII 414, RRII 417, RRII 430, P 26 and P 70 showed as positively influenced by assorted rootstocks compared to RRII 422, RRII 429, PB 330, P 21, P 64 and P 81.  A general negative influence of assorted rootstocks on the clones was observed in relation to the concept of girth potential of clones. In the early evaluation of these monoclonal blocks, P 70, P 21 and P 26 were promising genotypes for growth from among the pipeline clones.

Abnormal leaf fall caused by Phytophthora spp. is a serious disease of rubber (Hevea brasiliensis) in the traditional rubber growing regions of India. Twenty-five isolates from different rubber growing regions were subjected to molecular characterization and observed the variation if any. Internal transcribed spacers (ITS) of ribosomal DNA of the isolates were amplified with ITS 4 and ITS 6 primers. The rDNA- RFLP pattern was generated for all the isolates with different restriction enzymes. Among the different restriction enzymes tested, digestion was obtained only with two enzymes viz. Msp 1 and Alu 1. Uniform RFLP pattern generated for all the isolates tested from H.brasiliensis belonged to P.meadii. The RFLP patterns of generated rDNA of isolates from H.brasiliensis were compared with other Phytophthora species viz. P.capsici from pepper and P.palmivora from coconut showed variation.

Radiation vulcanization of natural rubber latex is a free radical assisted crosslinking reaction induced by .­radiation. It is carried out using a 60Co source at room temperature using n-butyl acrylate as sensitizer.  The optimum radiation dose for obtaining maximum properties for RVNRL film is optimized as 15 k.Gy.  The residual n-BA in the latex causes several problems in the products derived out of the latex.  The split-dose addition of n-BA was proposed to overcome this difficulty.  The order of addition of antioxidants also has some effect on radiation crosslinking reaction as antioxidants are free radical scavengers. Accordingly, the effect of different modes of addition of antioxidants on mechanical properties of the vulcanizates was studied. Among the different methods attempted, addition of antioxidant at mid time (M.I) and after irradiation

The large share of mature natural rubber (NR) holdings now remaining untapped, the undesirably high share of old/senile holdings and recent stagnation in the total NR cultivated area in the country are indications that growers’ interest in NR cultivation is on the wane. This is happening at a time when the domestic demand for NR is steadily on the rise. The prevailing low price of NR is blamed for this predicament. Results of the present study clearly indicate that harvesting rubber is still a profitable option for growers, provided weekly tapping system is adopted. Adopting self-tapping and confining tapping to the peak yielding period (May to January) will further enhance profitability of rubber tapping, especially when the price is low. Since there is no guarantee that rubber prices will increase considerably in the near future, not tapping the mature rubber trees is bad economics and a lost economic opportunity for the grower. It is likely that the grower is perhaps unaware of this. Creating awareness among growers about the futility of leaving mature rubber holdings untapped and how low frequency and self-tapping can substantially increase profits should be a central theme of extension efforts.