Abstract
Maize samples of plants from siblings of open pollinated populations from all parts of Italy have been cytologically investigated. It has been found that the amount of heterochromatin is on the increase in all parts of Italy but more so in the central regions. New knob forming segments have been located and their origin is thought to be from de novo formation of knob substance.
In the course of meiotic studies several chromosome aberrations have been observed. The rates of spontaneous mutation has also been investigated. These rates are higher in the south than north while in the center it is medium. Contrariwise the amount of heterochromatin is higher in the north and lower in the south. In view of this the frequency of spontanous mutations observed in supposed to be partly due to heterochromatin differences and chromosome interaction and partly due to chromosomal aberrations.
The possible role of heterochromatin in the structure and function of maize chromosomes has been discussed.
The influence of spontaneous mutations and the changing pattern of heterochromatin have been mentioned in relation to evolution of maize in Italy.
