Natural rubber (Hevea brasiliensis) cultivation in Côte d’ Ivoire has registered tremendous growth since its introduction in 1955. The expansion of area under rubber cultivation in the country has raised concerns on deforestation, degradation of natural ecosystem, food security etc. Rubber is generally intercropped with annual and perennial crops for its economic advantages. Mono-cultures of rubber trees are also coming up in the country. Rubber plantations generate secondary forest ecosystems which are likely to reverse environmental degradation in marginal lands. This paper reviews various works on rubber cultivation  in Côte d’ Ivoire from a policy perspective.

In recent years, consumption of natural rubber (NR) in India has been increasing and its production is on a declining trend. Therefore the supply of NR needs to be increased to meet its increasing industrial demand in the country. This can be achieved by expanding its cultivation to agro-climatically suitable areas and temporal monitoring of NR growing areas. Thus accurate, up to date and timely NR area statistics is essential for management of the Indian rubber plantation sector. Geo-spatial mapping of NR plantations was carried out in Karnataka, Maharashtra and Goa states using recent satellite data. Indian Remote Sensing Satellite Resourcesat I and II LISS III data for the year 2013 were used for estimating spatial extent of NR cultivation. Distribution pattern of rubber area across topographic variables was studied using ASTER digital elevation model (DEM). Area of NR estimated using satellite data was compared with traditional ground survey statistics of the Rubber Board. Area under NR above three years was estimated using satellite data for the year 2013-14. In Karnataka, NR area was 31,231 ha which was 4473.2 ha lower than official ground survey statistics of the Rubber Board (35704.2 ha). Negative deviation was attributed to large area under young plantations in Karnataka. NR plantations aged below three years couldn’t be delineated using satellite data because of their sparse canopy. Nearly 1133 ha of rubber area was delineated from Maharashtra. This showed 157.8 ha deviation compared to Rubber Board statistics (975.4 ha). Rubber area statistics of Goa was 424 ha as against ground survey area of 696.3 ha. Characterization of rubber plantation distribution over terrain parameters showed that majority of NR plantations in Karnataka and Maharashtra were distributed over 100 to 300 m elevation, less than 25 per cent slope and North and South facing aspects, whereas in Goa, this was 0 to 100 m elevation, 5 to 25 per cent slope and North and South aspects occupies majority of rubber area. This was the first time mapping of NR plantations has been conducted in Karnataka, Maharashtra and Goa and therefore a temporal monitoring is required to update young plantations and to understand its spatio-temporal shift in cultivation. The geo-spatial database of NR area statistics and its characterization in relation to elevation, slope and aspect can be used as baseline information for planning sustainable NR cultivation in the study area. Moreover, this study shows effectiveness of LISS III satellite data for NR area estimation which is up to date, cost effective and quicker than the traditional survey method.

The germination medium plays a key role in the production of good quality planting materials in rubber and strongly influences the sustainability of rubber plantation industry.  To study the effect of different media on germination and survival of seeds, an experiment was laid out using river sand as control and several other media such as raw coir pith, leached coir pith, new wood shavings, 6 months old wood shavings, raw saw dust, dried saw dust, rice husk, paddy straw, coconut leaf with a layer of soil, dried litter, rock powder, directly on the seed bed (without medium), soilrite and heaping of seeds on floor without any medium. All the germination associated parameters were significantly affected by the germination medium. In the experiment germination bed with river sand, leached coir pith, dried saw dust and soilrite recorded significantly higher germination percentage compared to all other germination media. The cost comparison of different germination medium showed that around 75 per cent of cost can be reduced by using coir pith as germination medium compared to river sand. Considering the cost, availability and germination capacity, leached coir pith is considered as an ideal seed germination medium for rubber.

Multidisciplinary evaluation of eleven clones of Hevea was initiated in 1993, at Nagrakata a cold prone Sub- Himalayan region of West Bengal. Among the clones evaluated RRII 208 and Haiken 1 exhibited the highest girth at the time of panel opening closely followed by the check clone RRIM 600. However, clones RRIC 104 and SCATC 93/114 showed maximum girth increment after twelve years of tapping. Haiken 1 and RRII 208 were the top rankers in terms of annual yield closely followed by PB 280 and RRIM 600 over the twelve years of tapping period. Haiken 1 ranked first in BO-1 and BI-1 panels followed by PB 280 whereas RRII 208 ranked first in BO-2 panel followed by Haiken 1 in terms of panel wise yield. The performance of these clones with respect to winter yield contribution varied from 56 – 62 %. Incidence of tapping panel dryness (TPD) was the minimum in PB 235 followed by Haiken 1 and RRII 300. In general, Oidium incidence was observed in all the clones but the lowest level was recorded in Haiken 1, RRII 208, SCATC 93/114 and RRIM 600. The intensity of wind damage varied from 0-18% among the clones. Shoot biomass accumulation was higher in SCATC 94/114 followed by Haiken 1 while the highest clear bole volume was recorded in RRII 308 followed by RRII 300 and PB 235. Results of this study revealed that among the 11 clones Haiken 1, RRII 208 and PB 280 were better adapted to the cold prone climate and found to be the most suitable clones for this region.

A study on the moisture retention characteristics of the rubber growing soils of Meghalaya indicated wide variation among different locations of the major rubber growing areas. The moisture retention in the surface layers at -0.033 MPa ranged from 21.05 per cent in Rongara (South Garo Hill district) to 36.08 per cent in Mendipathar (North Garo Hill district). However, the available water storage capacity (AWSC) did not show any variation as a result of the concomitant increase in the moisture retained at Byrnihat, -1.5 MPa. The moisture retention at the two tension ranges was found to be influenced by an aggregate effect of clay, sesquioxides, silt and organic matter. The moisture retained at -1.5 MPa was more than 0.4 times clay, suggesting that clay is either not well dispersed or some water is held by the gels. Silt was found to play an active role in conjunction with clay in the moisture retention at -1.5 MPa suggesting the colloidally active nature of silt in sub tropical soils. In general, rubber growing soils in Meghalaya have high water retention potential and this is of high practical significance for a rainfed crop like rubber. The data revealed that, about 31.4 per cent of available moisture is desorbed at -0.033 MPa and about 20.6 per cent at -1.5 MPa indicating that, this tension range could be of relevance to the water availability to crops like rubber grown under rainfed conditions.

High soil pH affects sustainability of tea crop adversely and it deteriorates the tea quality. There are large areas under tea plantations where soil pH is not suitable for its growing. Cultivation of rubber would be an alternate approach to use this land profitably. Growth of rubber plants in high pH (7.9) soil was higher than that of normal pH (5.4) during immature period which may be due to extra care taken in the form of application of additional organic manure to the plants of high soil pH. Variation in girth of different clones gave an opportunity to screen better adapted clone(s) under such type of soil. In general, chlorophyll content index and photosynthetic efficiency in high pH grow plants were lower than that of normal soil during juvenile phase. The study demonstrated the scope of expanding rubber in the abandoned tea growing areas of high soil pH under the climatic condition of Dooars areas of West Bengal.