Morphological and cyto-molecular characterisation of Dendrobium Sw.cultivars

Abstract

The research project “Morphological and cyto-molecular characterization of Dendrobium Sw. cultivars” was carried out at the Department of Pomology and Floriculture and the Department of Plant Biotechnology, College of Agriculture, Vellayani during 2003-2004. The objective of the study was to evaluate the growth and inflorescence production in Dendrobium varieties to carry out cyto-molecular characterization of Dendrobium varieties. Twelve varieties of Dendrobium of near flowering size plants were evaluated for their morphological and cyto-molecular characterization. The twelve Dendrobium varieties differed significantly for the morphological characters viz., shoot length, number of offshoots, shoot girth, leaf area, rate of shoot elongation, internodal length, flower colour, length of inflorescence, number of flowers per inflorescence, length of flower column and pedicel, thickness of inflorescence and leaf orientation. Significant varietal difference were observed among the twelve Dendrobium varieties for shoot length, shoot girth, internodal length of shoots, number of flowers, number of stomata on the adaxial and abaxial surface of the leaves, vase life, fresh and dry weight of inflorescence. High GCV and PCV were observed for shoot length, followed by leaf area, internodal length, length of inflorescence and number of flowers per inflorescence. The stomata on the surface of the leaf recorded ever highest GCV and PCV among all the characters. The shape of stomata ranged from oval shape to perfect round shape. Highest heritability values were recorded for number of stomata on the upper surface of the leaf. The genetic advance percentage was found highest for length of flowers column. In correlation studies, high positive phenotypic correlation was observed between number of flowers per inflorescence and length of inflorescence. The length of column had significant positive correlation with number of leaves, length of inflorescence, thickness of inflorescences and length of flower pedicel. Ranking of the varieties were done based on the value of selection indices. The variety V8 ranked first among the 12 Dendrobium varieties used in the experiment. The second and third ranks were gained by the varieties V4 and V1 respectively. The lowest rank i.e., the 12th rank was obtained by the variety V6. So from the selection index values, the variety V8 is the best one. DNA isolated from 12 varieties of Dendrobium was subjected to RAPD analysis. Among the 31 decamer primers, 24 yielded amplification products. By characterizing the 12 varieties of Dendrobium using morphological and cyto-molecular methods revealed that morphologically distinct and superior lines were genetically differentiable. Also the RAPD analysis gave a perfect differentiation of the varieties which is in line with morphological characterization.