In India, natural rubber (NR) cultivation is spread in an area of approximately 8.0 lakh hectares and the majority of soils under NR are red ferruginous soils belonging to the Ultisol/Alfisol order containing large proportion of iron and aluminium oxides and hydrous oxides and kaolinite dominated clay. The available literature on physical, chemical and biological properties of the NR growing soils in India, their fertility status and the impact of NR cultivation on soil properties are discussed. In the traditional NR growing belt,stretching from Kanyakumari district in the south to Dakshina Kannada district in the north, repeated cycles of rubber cultivation in the past one century, increased soil acidity, reduced organic carbon, available K, Ca and Mg contents and led to deficiency of Zn. For the soils in the North-east states of India, there are some indications that NR cultivation improved the organic carbon and available nutrient status compared to shifting cultivation/jhumming practices. Increasing soil reaction to the extremely acidic pH, declining base status and rising deficiency of Zn were reported from the traditional belt as well as from North-East India which warrants further studies and nutrient management strategies to maintain soil health and productivity on a sustainable basis.

Stressful environment is a limiting factor for rubber productivity in the traditional rubber growing areas and limits the expansion of rubber cultivation to newer areas in several rubber producing countries, including India. Conventional methods of Hevea breeding take several years to produce plants with desirable traits. Genetic transformation offers a viable approach for producing plants with desired traits within a short period of time. Since osmotin gene is reported to impart tolerance to abiotic and biotic stress, the present study on Agrobacterium mediated gene transfer was carried out with the gene encoding osmotin protein.Osmotin gene construct with CaMV 35S promoter and kanamycin as selectable marker was used for the purpose. Transformation frequency of 48 per cent was obtained from anther derived embryogenic calli.Molecular analysis with PCR and RT-PCR could confirm the integration of gene and its expression. The calli were subjected to PEG as well as salt stress for fixed intervals. Higher proline accumulation in transgenic cell lines compared to control was observed under PEG stress. Transgenic cell lines could tolerate higher concentration of salt (150 mM), whereas the control calli showed growth retardation even in lower salt concentration (50 mM). The regenerated plants from these transgenic lines are expected to perform well under stressful environments.

The paper revisits a study undertaken by the authors in 2008 on the trends in age-composition of mature area under natural rubber cultivation in India and reviews projected status for the period from 2008-09 to 2014-15. The projections of the earlier study showed that the share of area under the yield-declining phase would rise to touch 53.3 per cent by 2011-12 before falling to 46.0 per cent by 2014-15. The earlier study had also highlighted inconsistencies in the official data and recommended a national census of rubber area for fixing the same. However, the earlier study failed to capture the postponement of the uprooting of rubber trees beyond 22 years of tapping age and the resultant emergence of a senile group of trees having more than 22 years of tapping age. Due to retention of aged trees, the gap between the projected figures of mature area and the corresponding official figures sharply widened from 2.2 per cent in 2008-09 to 25.3 per cent in 2014-15. The area occupied by trees having more than 22 years of tapping age steadily grew by 144.7 per cent during the period from 2008-09 to 2014-15. In absolute terms, the area under this age-group increased from 10,255 hectare to 99,313 hectare with important policy implications. The results of the study reconfirmed the need for a national census of rubber area, as proposed in the earlier study.

In many plant species, somatic embryogenesis receptor kinase (SERK) gene, belonging to the plant receptor kinase superfamily and which encodes a leucine-rich repeat receptor-like kinase, is closely related to induction of somatic embryogenesis. SERK gene having prominent role in somatic embryogenesis has been characterized from monocotyledonous and dicotyledonous plants. In the present study, a partial SERK gene was cloned and characterized from Hevea brasiliensis (clone RRII 105). The genomic DNA sequence encoding SERK gene in H. brasiliensis was amplified with gene specific primers designed based on the consensus sequence reported in other crops. Under optimum PCR conditions, a single band of approximately 0.6 kb size was amplified from genomic DNA and the amplicon was cloned and sequenced. The partial HbSERK gene obtained was 612 bp in length with one intron. Homology search and sequence analysis demonstrated a high degree of identity with SERK genes reported from other plant species. RT PCR analysis revealed higher expression of HbSERK gene in embryogenic callus, while no expression was detected in mature leaf indicating that HbSERK is associated with somatic embryogenesis induction. This is the first report of the characterization of a SERK gene in H. brasiliensis and the sequence was deposited to the GenBank under the accession number KJ451561.

Composite samples of twenty three organic fertilizers/manures were collected from the market and analyzed for moisture content, pH, electrical conductivity, total organic carbon, C: N ratio, total nutrients and heavy metals and the data were compared with quality control guidelines for city compost as per Fertilizer Control Order, 1985. It was observed that the extent of compliance varied widely with respect to different parameters. High nutrient contents, especially nitrogen, were observed in majority of the samples indicating possible adulteration with chemical fertilizers. Chromium content was very high in about 50 per cent of the tested samples. Lead content was above the toxic limit in four per cent of the samples. Cadmium, copper and zinc contents were within the permissible limits in all the samples. All the samples contained very high levels of iron. During the analysis of the samples by acid digestion, varying amounts of sand or powdered rock were left as residue, indicating mixing with such materials, possibly again as adulterants. The study clearly points to the need for establishing quality control parameters for organic fertilizers, and regulating the quality of various products marketed as organic fertilizers. Proper labeling of these fertilizers should be an immediate priority. Phosphorus fertilizers and other inorganic fertilizers commonly used in Kerala were also tested for their heavy metal contents what about lead, cadmium and zinc were within the limits specified by Food and Agriculture Organization/World Health Organization.

A clonal nursery evaluation was conducted with seven superior ortets selected from a population of 340 seedling trees grown under the agro climatic conditions of Assam in order to evaluate their performance when cloned in comparison to the performance of the original mother tree and a popular check clone. Girth at 5th year of planting and girth increment of the ortet clones, RRSG 9 and RRSG 4 in nursery trial and the corresponding mother trees were significantly higher than that of the check clone RRIM 600. Mean juvenile yield of RRSG 9 with or without stimulation using 2.5 per cent ethephon and the mean yield over 11 years of tapping (mature yield) of the mother tree were significantly higher than that of the check clone. Mean juvenile yield of RRSG 8 without ethephon in nursery trial was significantly higher than RRIM 600 but it was not so in case of mother tree. Juvenile yield of RRSG 8 with 2.5 per cent ethephon was at par with the check clone in the clonal nursery. The performance of RRSG 1 was also noticeable with good pre-monsoon yield. The ortets in the present study maintained the character of their mother tree under bud-grafted condition also, as evidenced by the positive correlation between yield of mother trees and their ortet clones. Clones RRSG 9 and RRSG 8 along with RRSG 1 proved promising for further evaluation in large scale trial.