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.

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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.

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The choice and recommendation of a variety for commercial cultivation are influenced by genotype x environment interaction (GEI)). The complication of genotype by environment interaction (GEI) is that usually involves layout of trials in various seasons, making it difficult to identify the genotype adapted to different environments. Twenty sugarcane clones and four standard checks were evaluated under three environments within the tropical climate. Additive Main Effects and Multiplicative Interaction (AMMI) model was applied to assess the extent of genotype x environment (GE) interaction and also the stability of sugarcane clones across the environments. The significant difference was observed by AMMI analysis among the tested clones and environments. The sum of the first two principal components conferred to 63.6 per cent of the total of G x E interaction. In the present study, the genotypes G24 (Co 88025), G23 (CoV 94101) and G20 (Co 16001) recorded in high mean yield and higher Principal Component Analysis (PCA) scores; hence, these materials specifically suited to the favorable locations. Since the genotypes Co 15021(G19), Co 0240 (G3), and Co 13001(G7) were near the center point of the axes and hence were influenced by the environment. These clones recorded higher cane yield and stability and suitable for cultivation in different environments. The utilization of the AMMI model made it easy for the visual comparison and identification of exceedingly superior genotypes for every set of environments.

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