Classificatory analysis for genetic diversity in dahlia

Abstract

The experimental material constituted 18 varieties of dahlia and the experiment was conducted in randomized block design with five replications during 1998-99 winter season. Recommended package of practices were followed to raise the crop. Observations were recorded on three random competitive plants from each replication for plant height, stem diameter, number of primary branches, internode length, number of leaves, length and width of leaf, leaf area, plant spread, days to first bud initiation, bud development period, bud development at colour break stage, days from colour break to opening, days to first flowering, days to full opening of flower, bloomlife of flower, number of flowers per plant, ornamental crop duration, diameter of main flower, diameter of secondary flower, diameter of last flower, stalk length of main flower, stalk length of secondary flower, stalk diameter of main flower, stalk diameter of secondary flower, number of ray florets in main flower and secondary flower, length, width and thickness of petal, number of tubers per plant, weight of tubers per plant, length and thickness of largest tuber, length and thickness of smallest tuber. Mahalanobis' 0 2 statistic was used to quantify genetic diversity among the genotypes and clustering by Tocher's method was done following Rao [1]. Canonical analysis was carried out according to Anderson [2]. For numerical classificatory analysis, the general similarity coefficient (SG) of Gower [3] was used as a measure of resemblance between different operational taxonomic units or OTUs (entries included in the study) and SG values were calculated as per Sneath and Sokal [4]. Based on the matrix of the SG values, phenograms (dendrograms) were constructed using the UPGMA (unweighted pair group method using arithmetic average) technique in one of the SAHN (sequential, agglomerative, hierarchic, non-overlapping) clustering methods [4] and the clusters were identified at appropriate phenon levels.