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Abstract
Chromosome length is a basic karyotype characteristic. This paper shows, on the basis of total chromosome length (TCL) measurement, that this value is not a stable one. TCL varies among different c-metaphases from one meristem; the average TCL is different for (a) different pre-treatment agents; (b) different pre-treatment times for the same pre-treatment agents; and (c) between siblings treated simultaneously. In the same way, total chromosome volume (TCV) is not a suitable characteristic for chromosome size comparison. To solve the problem of chromosome size comparison the following standardization of TCL measurement is proposed: to determine TCL in c-metaphases with the chromosomes contracted to maximum level and still retaining all measurable karyotype characteristics. This way of standardization requires a pre-treatment method providing c-metaphases suitable for standardized TCL measurement. The paper also brings one new chromosome number to science: Onosma thracica, 2n = 14.
Acknowledgements
Support for this research was provided by APVV Grant Agency (APVV 0320-10), and VEGA grant agency (VEGA 1/0173/11). My thanks are also due to Vladislav Kolarčíik and Valeria Kocovaá (Faculty of Science, P.J. Safarik University, Košice) for providing material and data on genome size of Onosma thracica and Trifolium pratense, respectively, to Marek Slovák (Botanical Institute of Slovak Acad. Sci., Bratislava) for providing material of Picris hispidissima and to Pavol Mártonfi (Faculty of Science, P.J. Safarik University, Košice) for identification of several taxa.
