R K Sud

AFLP-Based Genetic Diversity Assessment of Commercially Important Tea Germplasm in India

India has a large repository of important tea accessions and, therefore, plays a major role in improving production and quality of tea across the world. Using seven AFLP primer combinations, we analyzed 123 commercially important tea accessions representing major populations in India. The overall genetic similarity recorded was 51%. No significant differences were recorded in average genetic similarity among tea populations cultivated in various geographic regions (northwest 0.60, northeast and south both 0.59). UPGMA cluster analysis grouped the tea accessions according to geographic locations, with a bias toward China or Assam/Cambod types. Cluster analysis results were congruent with principal component analysis. Further, analysis of molecular variance detected a high level of genetic variation (85%) within and limited genetic variation (15%) among the populations, suggesting their origin from a similar genetic pool.

Catechin and catechin fractions as biochemical markers to study the diversity of Indian tea (Camellia sinensis (L.) O. Kuntze) germplasm.

The heterogeneous Indian tea germplasm includes ‘China’, ‘Assam’, ‘Cambod’, and their hybrids which were evaluated using biochemical markers viz., total catechin and their fractions, for varietal identification and characterization. Principal component analysis (PCA) of biochemical characters showed that the total catechin and trihydroxylated catechin has higher eigenvalues. The first two principal components (PCs) could differentiate more than 90% of the clones studied. This grouping based on first two principal component matrices differentiated ‘China’, and their hybrids with ‘Assam’ and ‘Cambod’ variety. Morphologically indistinct large‐leaved ‘Cambod’ variety and ‘Assam’ varieties could not be differentiated using biochemical markers, since both varietal types taxonomically belong to a single species. Clones of ‘China’ type showed low total catechin content and catechin ratio which are distinctly grouped. The ‘China–Assam’ and ‘China–Cambod’ hybrids formed intermediate groups between ‘China’ PC group and ‘Cambod’/‘Assam’ PC groups, providing evidence for genetic control of catechin ratio variation. Tea clones which are differentially positioned in the PC group could be explained based on the genetic contribution by other varietal type as parents. This biochemical characterization will be a useful tool in the development of quality‐tea clones with different proportion of total catechin and their fractions.

Analysis of the essential oil of large cardamom (Amomum subulatum Roxb.) growing in different agro-climatic zones of Himachal Pradesh, India.

BACKGROUND The aim of the present study was to investigate variations in the chemical composition of the essential oil from seeds of large cardamom grown at different altitudes in Himachal Pradesh, India. The composition of the essential oil was determined by gas chromatography (GC), gas chromatography-mass spectrometry (GC-MS) and gas chromatography-olfactometry (GC-O). RESULTS The oil components showed qualitative and quantitative variations in the composition. GC and GC-MS analysis led to the identification of 55 compounds representing 98% of total oil. Major components in the oil were 1,8-cineole, α-terpineol, DL-limonene, nerolidol, 4-terpineol, δ-terpineol, δ-3-carene, β-myrcene, germacrene D, α-terpinene and longifolenaldehyde. The oil yields obtained were 9.8-19.5 g kg(-1). Cardamom oil from Himachal Pradesh was found to contain new compounds, viz. 4-terpineol, δ-3-carene, trans-sabinene hydrate, 1-phellandrene, α-terpinene, bicyclo-germacrene, isopinocarveol and ledenoxid-II. α-Terpenyl acetate, the major constituent of small cardamom, was also detected in the oil of large cardamom grown in Himachal Pradesh. Application of aroma extract dilution analysis revealed 35 compounds having aroma impact with the flavour dilution factor ranging from 2 to 1024, and 34 of these compounds were identified. The five most intense aromatic components are dl-limonene, 1,8-cineole, β-myrcene, α-pinene, α-basabolol. This is the first time that the characterisation of odour-active compounds has been carried out on large cardamom. CONCLUSION The presence of 4-terpineol, δ-3-carene, trans-sabinene hydrate, 1-phellandrene, α-terpinene, 1-terpineol, bicyclogermacrene, isopinocarveol, ledenoxid-II, longifolenaldehyde and α-terpenyl acetate make the aroma of the oil different from large cardamom oil of Sikkim and could offer potential as a new food flavour.

High Level of Genetic Diversity Among the Selected Accessions of Tea (Camellia sinensis) from Abandoned Tea Gardens in Western Himalaya

To revive cultivation of the tea unique to the western Himalayan region, it is important to evaluate the seed-derived bushes available in the area’s abandoned gardens. This study used quantitative leaf characters, catechin content, and AFLP markers to assess these China cultivar type bushes. Compared with other China cultivar germplasm, these accessions showed a higher level of diversity among themselves. Among the quantitative morphological characters, leaf length is important in distinguishing the accessions studied, with a high loading value in the principal component analysis. The catechins and AFLP markers displayed the genetic makeup of the accessions. Other than total catechins, the trihydroxylated catechins showed a high loading value in differentiating the accessions. The genetic control of the ratio of dihydroxylated and trihydroxylated catechins is found to be based on a correlation with AFLP markers. The genetic similarity between Kangra Asha and Kangra Jat suggests that Kangra Jat must be descended from Kangra Asha. Kangra Jat is well adapted to local environmental conditions, as is evident from its high catechin content.

Germplasm appraisal of western Himalayan tea: a breeding strategy for yield and quality improvement

Western Himalayan tea represents the status of Geographical Indication in the form of “Kangra Tea” which is unique to the tea grown world over due to its delicate flavor and high quality. The tea germplasm resources of western Himalayan region include selections from the commercial tea estates, abandoned tea gardens of Kangra valley and elite tea clones of CSIR-IHBT, Palampur. Data were recorded for different morphological traits contributing to yield and the biochemical parameters were evaluated using standard HPLC procedures. Multivariate clustering of the data differentiated the germplasm resources into distinct groups based on comparisons among the clusters for leaf size and biochemical parameters. Leaf size differentiated the tea accessions into six phenotypic groups, while shoot density which is an important yield parameter was observed to be independent of leaf size. On the basis of total catechin and caffeine contents, tea accessions were differentiated into nine groups of which Group I in comparison with other groups, recorded the highest total catechin content, moderate to high caffeine level and high astringency factor (AF). Epicatechin gallate (ECG) had a significantly high correlation with AF, implying that high levels of ECG are critical along with corresponding levels of Epigallocatechin gallate (EGCG) for the production of Theaflavin 3,3′digallate (TFDG) which is an important quality constituent providing astringency and briskness to black tea liquor. Sustainability of tea breeding programme can be achieved through organization of germplasm resources and by utilizing elite tea genotypes in breeding programme.

Integrated Weed Management in Plantation Crops

Plantation crops are long-term crops established for commercial interest. Major plantation crops are tea (Camellia spp.), coffee (Coffea arabica L.), oil palm (Elaeis guineensis Jacq.), areca nut (Areca catechu L), cardamom (Elettaria cardamomum Maton and Amomum subulatum Roxb.), coconut (Cocos nucifera L.), cashew (Anacardium occidentale L.), cocoa (Theobroma cacao L.), and rubber (Hevea brasiliensis Mull. Arg.). Being long-term crops, and often grown as monocultures, plantation crops are severely infested with weeds. This chapter deals with the nature and effect of the weed menace in the above mentioned crops along with methods adopted for weed management. In the plantation crops, weeds are managed by physical, mechanical, and chemical methods similar to those generally adopted in arable/field crops. However, there are reports on the use of low-density polyethylene sheets for mulching interrow space and mowing between the rows to control weeds. Planting smother crops or leguminous cover crops and intercropping in the row space, and deploying grazing animals are the biological methods for weed management in some of these crops. Integrated approach involving a combination of cultural, mechanical, and biological weed control methods is also adopted for combating weeds in an effective, economical, and eco-friendly manner.