INFLUENCE OF SOIL ACIDITY AND ENVIRONMENT ON THE FREQUENCY AND LOCALIZATION OF CHIASMATA IN MAIZE (ZEA-MAYS L.)

In order to assess the influence of soil acidity and environment on th e frequency and localization of chiasmata, seven maize genotypes, four of them heterozygous and three homozygous, were cultivated ill the fi eld and in a greenhouse on acid and corrected soil. The analyses demon strated a differential behavior among genotypes with respect to intera ction with environment and level of soil acidity. For most genotypes t here was an increase in the frequency of chiasmata when they were grow n on corrected soil both in the field and in the greenhouse. Under all conditions tested the heterozygous genotypes presented higher chiasma frequencies than did the homozygous genotypes. These results show tha t the rate of genetic recombination of a population, estimated by chia sma frequency, may be increased when the material is cultivated in soi l of good fertility.