A comparative study of recombination breeding and polycross breeding in rubber was attempted based on the results of long term yield from small scale evaluations of hybrid clones generated from the 1986 hybridization programme and the 1989 polycross breeding programme undertaken in the Rubber Research Institute of India. A total of 295 hybrids and 135 polycross progeny selections were evaluated in 14 field trials over 13 years of tapping. The long term yield and yield trends of elite clones identified from the two breeding programmes as well as their stability in yield over the years were compared. Recovery of superior individuals from the initial selections in terms of long term yield was higher in the case of polycross breeding (33.3%) as compared to recombination breeding (20%). The proportion of exceptionally high rubber yielders with >100 g t-1 t-1 was also higher among polycross selections (1.48% of the initial number of 135 clones and 6.7% of the initial 30 selections) compared to hybrids obtained from recombination breeding (1.02 % of the initial number of 295 hybrids and 3.75% of the initial 80 selected hybrids). The best among the hybrids were three clones: 86/122 (P 020) with 132.5 g t-1 t-1, 86/111 (P 021) with 117.2 g t-1 t-1 and 86/428(P 027) with 112.8 g t-1 t-1 and among the selections from half-sib progenies were two clones HSPB252/132 (P 070) yielding 113.1 g t-1 t-1 and HSCh26/161 (P 064) yielding 100.2 g t-1 t-1 over 13 years of tapping. All the five exceptionally high yielding clones proved to possess stability in yield over the years and are in the pipeline for commercial release, undergoing farmer participatory multilocational evaluation. The three highest yielding hybrids, P 020, P 021 and P 027 are the progenies of the cross RRII 105 x RRII 118. The results of this study form the basis of comparison and drawing conclusions on the suitability of the two parallel breeding approaches to attain specific goals. 

Negotiations for entering into a larger trade agreement between Association of South East Asian Nations (ASEAN) and its six free trade agreement (FTA) partners viz. India, China, Japan, Australia, New Zealand and South Korea called Regional Comprehensive Economic Partnership (RCEP) agreement are in the final stages. The agreement is expected to have far reaching impact on the world rubber industry as it covers the major producers and exporters of raw rubber and rubber products in the world. The challenges of RCEP on Indian rubber industry are evident from the higher rate of growth in imports (20%) than exports (11%) of rubber and rubber products with these countries. The present study analyses the export performance of rubber and rubber products of India in the RCEP region. It was found that among the major export items of India, only new pneumatic tyres (HS 4011) and reclaimed rubbers (HS 4003) showed export potential in the region and the products classified under other articles of vulcanized rubber other than hard rubber (HS 4016) had comparative disadvantage in the RCEP market. Moreover, the benefits due to trade creation and trade diversion under the RCEP are limited for export of rubber and rubber products from India. Therefore, it is argued that the prospects of market access to major export items of India, such as products under HS 4011 and HS 4016 are largely dependent on creation of trade competitiveness rather than market access due to tariff liberalisation. The present study observed that further tariff liberalisation under the proposed RCEP agreement may widen the trade deficit of India in rubber and rubber products. This will have far reaching implications on the domestic rubber and rubber products manufacturing industry.

Water quality in major land use systems of Western Ghats in Kottayam and Idukki districts of Kerala. Rubber Science, 32(2): 137-149. A study was conducted during the period 2015-2017 to assess the water quality in rubber, tea and cardamom dominated watersheds in the Western Ghats of Kottayam and Idukki districts in Kerala state. Watersheds were delineated using survey of India topographic maps, satellite images and field information. Watershed dominated by rubber plantations (30.3 km2) was delineated at Poonjar area which is on the western slope of the Western Ghats, in Kottayam district. Watersheds of tea (20.5 km2) and cardamom plantations (18.6 km2) were delineated at Vandipperiyar and Udumbanchola areas, respectively in Idukki district. Sampling sites were identified depending on watershed area and accessibility after detailed field  investigations to ensure distribution. Water samples were collected during post-monsoon season of 2015, pre and post-monsoon seasons of 2016 and pre-monsoon season of 2017, and analyzed for important physico-chemical parameters following standard protocols. The study showed that total dissolved solids, total hardness and electrical conductivity were significantly higher in groundwater and surface water in watersheds of tea and cardamom compared to that in rubber watershed. Significantly higher contents of minerals and nitrate were also observed in samples from watersheds of tea and cardamom compared to rubber. The results indicate higher run off and leaching of nutrients from tea and cardamom plantations consequent to the higher agricultural inputs in the cultivation of these crops in steeper slopes in the upper reaches of the Ghats. Though the effect of agro-management practices was reflected in the physico-chemical properties of ground water and surface water, all these parameters, except pH of groundwater in tea watershed, were within the limits specified for drinking water. Heavy metals (Pb, Cd and Cr) exceeded the permissible limits of drinking water in some samples in the three watersheds while Cu was within the limits. Bacteriological analysis confirmed the presence of fecal coliform bacteria in groundwater and surface water samples of all the three watersheds. Analysis of water samples for pesticide residues showed that organo-chlorines, organophosphates and pyrithroides were below detection limit in all the three watersheds. Dissolved oxygen content of surface water was significantly higher in samples from rubber watershed compared to tea and cardamom, indicating better health of water resources in the rubber system.  

In Hevea brasiliensis, somatic embryogenesis based regeneration system is the only in vitro system which provides a platform for genetic manipulation studies. During somatic embryogenesis, quality of callus is a key factor for the production of embryogenic callus and further regeneration, and therefore improving the quality of primary callus is a key step. The present study investigates the effect of explant cold treatment and BA on callus induction and proliferation. Cold treatment applied before and after culturing up to 48 h did not significantly promote the callus induction and growth, but seems to be similar to untreated control. However, prolonged incubation for 72 h dramatically reduced callus induction rate. Supplementation of BA on callus induction medium enhanced the callus induction frequency as well as callus growth and proliferation with an optimum being at 2.0 mg L-1 BA along with 2.0 mg L-1 2, 4-D. Somatic embryogenesis with minimal proliferation of embryogenic callus and further regeneration into whole plants within eight months’ time is the unique observation found in this system. Regenerated plantlets were successfully acclimatized and were morphologically normal in appearance. This is the first report on clone RRII 414 plantlets regenerated through somatic embryogenesis and field establishment. 

Twenty clones evolved by hybridization, selection and polyploidy breeding were evaluated in comparison with clone RRII 105 in two large scale trials laid out in 1993 at the Central Experiment Station of the Rubber Research Institute of India. Long term performance of these clones over 25 years under S/2d3 6d/7system of tapping without stimulation for 14 years and with application of yield stimulant for three years was studied. Growth and timber volume at 25 years were also assessed. The unstimulated yield over 14 years of tapping among the 22 clones in the two trials established three clones RRII 417, RRII 430 and PB 330 to be superior to RRII 105 and a total of nine clones (RRII 414, RRII 429, RRII 402, RRII 403 and RRII 55 in Trial 1 and RRII 422, RRII 52, RRII 410 and RRII 427 in Trial 2) to be comparable with RRII 105. In terms of long term yield over 17 years of tapping, RRII 430 (77.1 g t-1 t-1) and PB 330 (73.6 g t-1 t-1) were the highest yielders with 17-18 per cent higher yield than clone RRII 105. The response to stimulation in terms of the improvement in yield of the clones in the renewed panel on stimulant application over the unstimulated yield for 14 years ranged from 0 to 56 per cent. Clones RRII 414, RRII 422 and RRII 427 did not show any response to the application of yield stimulant. Among the 12 promising clones, better response to stimulation than RRII 105, with yield increase ranging from 6.5-22.4 per cent was exhibited by eight clones. Among these, RRII 429 (22.4%) and RRII 52 (21.0%) were the two toppers. The low incidence of tapping panel dryness in clones RRII 410 (5.3%) and PB 330 (10.5%) after 17 years of tapping is noteworthy. Clones RRII 430 and RRII 422 showed a lower percentage of TPD affected trees than RRII 105.  Clones PB 330 and RRII 52 exhibited the highest girth of more than 100cm after 17 years of tapping. Other high girthing clones were RRII 402, RRII 414 and RRII 417. Bole volume was highest in clone PB 330 (0.38m3tree-1) followed by clones RRII 417, RRII 414, RRII 407, RRII 402 and RRII 410 with 0.16 m3tree-1 at 25 years. The results established RRII 417, PB 330 and RRII 414 to be dual purpose latex–timber clones while RRII 430 was a stable high latex yielder.

Delineation of spatial variability in soil fertility parameters is of critical importance to identify fertility constraints of a given site and for effective soil resource management. In India, rubber is cultivated in regions varying in physiography, climate and soil properties and the soil fertility will also vary at different spatial scales. In this article, the spatial variability in available sulphar status in the rubber growing regions of South India is presented. Geo-referenced soil samples were collected from rubber growing regions of South India, analysed following standard analytical protocol and the available status was mapped geostatistically following kriging interpolation technique. Wide spatial variability, both intra and inter region was observed in available S status. In general, rubber growing regions in North Kerala, Karnataka, Goa and Maharashtra were low in available S status. Sulphur nutrition of rubber has not received adequate attention so far and these maps identify regions which need special attention with respect to S nutrition, for conducting response/case studies and surveys for future crop husbandry.