Alice KurianManjusha, C MKAU2019-05-252019-05-252000171765http://krishikosh.egranth.ac.in/handle/1/5810104532PGA comparative evaluation of the morphological, histological and biochemical features of various Adhatoda accessions collected from different parts of Kerala was carried out in the Department of Plantation Crops and Spices, College of Horticulture, Vellanikkara during 1998-2000 for characterizing the germplasm accesions and to ascertain their species identity. The 52 accessions after evaluating for their morphological characters were classified into three clusters, which represented A.zeylanica (7types), A.beddomei (20) and intermediate types (25). Key characters which served for distinguishing between the two species were identified as plant habit, leaf size and shape, stomatal distribution, streaks on corolla and pubescence of ovary. A.zeylanica types were taller in habit with more number of branches, long petiole, broadly elliptic lanceolate hypo stomatic leaves and white flowers with purplish streaks inside and large pubescent ovary. A.beddomei types were small with lesser number of branches, short petiole, narrowly elliptic lanceolate amphistomatic leaves, with white flowers without purplish streaks inside and small glabrous ovary. Intermediate types showed both the leaf and floral types emphasizing the possible occurrence of natural hybrids in the genus. The variation in the elution pattern of phenols and terpenoids typical to the species makes them to be effectively utilized in the biochemical characterization of the species. A.zeylanica types showed a higher alkaloid content (0.66%) compared to intermediate types (0.38-0.55%) and A.beddomei (0.27-0.32%). Isozyme and enzyme studies also showed variation between accessions. However, further trials involving more enzyme systems is necessary for characterization of species. High heritability (broad sense) accompanied with high genetic advance for leaf area and petiole length indicates that most likely the heritability is due to additive gene effects and selection based on such traits may be effective. The growth was found progressive upto 12 MAP when it yielded more fresh and dry weights of whole plant, leaf, stem and root compared to 6 MAP. A higher alkaloid content as well as number of spots for phenols, terpenoids and alkaloids in the dry season compared to wet season indicate the influence of moisture stress on accumulation of secondary metabolites and the need for scheduling harvesting time coinciding with this season.ennullThesis