CHANGES IN SILVER-STAINING OF NUCLEOLUS O RGANIZER REGIONS IN INTERVARIETAL BARLEY HYBRIDS

The size of Ag-NORs is root meristem cells was studied in two varietie s of spring barley and in their F1, F2, and F3 hybrids. It is shown th at varieties and hybrids can be characterized by two parameters: the m ean of the total Ag-NOR area in cells and its coefficient of variation . The total Ag-NOR area per cell was shown to increase in hybrids; thi s increase is apparently associated with amplification or activation o f ribosomal genes. As compared with parent forms, hybrids were charact erized by lower coefficients of variation of the total Ag-NOR area; th ese lower coefficients are evidence for higher stability of their geno mes.