A field survey was conducted in 43 rubber holdings of West and South Tripura districts to understand the occurrence, severity and seasonal variation of tapping panel dryness (TPD) of rubber. The lowest mean TPD of 7.5% was observed in BO-1 panel and the highest in BI-2 panel. The maximum mean TPD of 13% was observed at Kariamura II followed by Mirza (12.9%), Promodnagar (11.3%) and Rangamala (11.1 %). The lowest TPD incidence was observed at Baghmara (1.9%) followed by Dariabagma (2.9%). The variation of TPD was observed for six consecutive seasons from winter (December-January) of 2007-08 to summer (April-May) of 2009. Mean TPD was maximum (16.6%) during the winter season of 2008-09 and minimum (9.1 %) during the summer season of 2008. TPD intensity was observed to increase from summer to winter season. A tapping rest of around two months from middle of February to middle of April reduced TPD marginally in the subsequent summer season compared to that in the previous winter season. 

Cultivation of Hevea brasiliensis is being extended to drought-prone marginal areas and therefore, identification of suitable clones that can survive under adverse climatic conditions is highly essential for enhancing the production of natural rubber in India. Identification of genes/factors contributing to stress tolerance will help in understanding the molecular basis of drought tolerance. Relevance of seven drought responsive genes (identified earlier) was studied in drought sensitive/tolerant clones. Studies on net CO2 assimilation rate (A) and stomatal conductance (g_s) indicated that clones such as RRIM 600 and RRII 430 were relatively more tolerant to drought than RRII 105 and RRII 414. The gene expression studied by quantitative PCR method demonstrated strong association of genes such as CRT/DRE binding factor and ABC transporter protein with drought tolerance, as evidenced by their up-regulation and down-regulation, respectively only in the drought-tolerant clones (RRIM 600 and RRII 430) when exposed to drought stress. Expression analysis of these genes in more Hevea clones would further strengthen the significance of their association with drought tolerance potential.

Hevea latex contains several non-rubber components in addition to rubber particles. Among them L-quebrachitol (methyl inositol), a commercially important compound, is prominently present. Hence attempts were made for its isolation from different sources of latex serum. In the present study, latex serum of four clones obtained by four different extraction methods, viz. coagulation of latex with acetic acid, coagulation of latex with alcohol, centrifugation of latex and low temperature extraction, as well as the effluent of latex centrifuging factory were used for quebrachitol separation. The results showed that yield/ extraction rate of quebrachitol from natural rubber latex varied from clone to clone and with different methods of serum preparation. The highest recovery (1.4%) was obtained from the serum obtained by the latex centrifugation method in the clone RRII 430. Of the four serum sources used, serum from latex centrifugation gave the best results in all the clones. Among the four clones, RRII 430 gave the highest yield of quebrachitol followed by RRII 414, RRII 105 and RRIM 600 which had similar levels of extraction rates irrespective of the source of the serum. Recovery was the lowest (0.005%) in factory effluent which may be due to prolonged preservation of latex. 

The results of two studies on planting materials raised by different budding techniques are discussed. Modified young-budded polybag plants of RRII 105 were field-tested at 11 locations in the traditional rubber growing tract of Kerala extending from Thamarassery in Kozhikode District to Punalur in Kollam District, in comparison with conventional brown (eight locations) and green-budded polybag plants (three locations). Both the test and control saplings were raised in the holdings during the planting season of 2002 in compact blocks with plot size varying from 250 to 500 plants, following standard practices. Direct-seeded bud-grafted plants grew at a faster rate soon after field planting than budded stumps. However, after seven years of growth, the modified young buddings were comparable in girth and tappability with brown-budded stumps in five out of eight locations, and with green-budded stumps in all the three locations. Significantly higher girth seen in young budding in two out of eight locations might be due to significant difference in the initial quality of planting materials. Data show that differences in initial girth between modified young-budded plants and brown-budded plants get reduced over time. It appears that commercial value of young budding as a method of propagation is not superior to conventional brown and green bud dings. Another experimental planting at Rubber Research Institute of India also revealed that girth and tappability of trees that originated from brown, green and modified young budding techniques were statistically on par at the time of opening. 

From the experiments in holdings and from the statistically laid out trial, it is inferred that, with the adoption of uniform and scientific agromanagement practices, girth attainment and immaturity period of planting materials that originate from different budding techniques within the same clone are comparable. 

Various technologies developed in rubber processing are being transferred to the group processing centres of Tripura. The extent of adoption of the technologies by these centres is discussed. Most of the group processing centres process latex into Ribbed Smoked Sheets (RSS) and some are selling latex to other entrepreneurs. Even though good infrastructure and trained personnel are available in all the centres, some deviations in processing from the recommended practices like dilution and sieving of the latex, dosage and mixing of the acid, thickness of the RSS, temperature of the smoke house, etc. were noticed in all group processing centres. Full capacity utilisation was found only in pre-winter months. The infrastructure made for making RSS remains unutilised in centres which are selling latex. Many centres are not grading the sheets before sale and most of them sell the sheets locally. The study underlined the necessity of refresher trainings and awareness programmes to follow the correct processing techniques involved in RSS processing. 

The present study was undertaken to assess the utility of qualitative traits of Hevea brasiliensis in identification of diverse parents for hybridization programmes. Morhophological traits of 30 H. brasiliensis clones were scored based on their descriptors and analysed to group the clones based on their similarity. Ortet clones formed three clusters but did not reveal any relation with the geographical origin of the clones. UPGMA dendrogram constructed using similarity measure of 30 clones revealed four major clusters. Cluster I with 10 clones showed the lowest similarity with other clusters. The results of the present study indicate that there exists a genetic relationship among the clones clustered together based on discrete morphological traits. The possibility of using parents from distant clusters in future breeding programmes is discussed.