CYTOGENETIC STUDIES ON CHROMOCENTRES IN RADISH (RAPHANUS SATIVUS L.). I. VARIETAL POPULATIONS AND THEIR F1 HYBRIDS

The number and distribution of chromocentres have been studied in 9 varietal populations of radish (Raphanus sativus L.) and their 6 F1 hybrids. The mean number and the distribution of chromocentres in the interphase nuclei were found to be characteristic for a population. The varietal populations differed significantly from each other in this heterochromatin phenotype, indicating different degree of heterochromatinization in them. In the F1 hybrids the number of chromocentres averaged midway between their parents. The population having a narrow range of distribution of chromocentres dominated over those having a wider range of the same. It has been concluded that the amount and the distribution of constitutive heterochromatin as inferred from the chromocentre counts, are genetically controlled in radish.