This investigation was conducted at Sakha Research Stalion from 1997
through 2002 growing seasons. White synthetic variety Sakha-6. as a new maize
variety, was used in this sludy to utilize its genetic variability in improving yielding
potentiality via 8₁ lines per se. A lotal of 2008₁ families from Sakha·6 were tested
during the 2001 season in two separate experiments under low and high N doses (i.e ..
70 a~d 120 Kg N/faddan. respectively). Differences between the two nitrogen levels were not significant for alf traits
except grain yield and ear diameter. However, the means were higher under the high
nitrogen level for all traits except reststaoce to late wilt disease and silking date. Genetic variance was significant for all traits at each of Ihe two nitrogen levels
and from both levels. while. the interaction between genetic variance and variance
due to nitrogen levels was not significant for afltraits except resistance to late wilt
disease. Phenotypic and genotypiC variances were increased under the high nitrogen
level for grain yield. resistance to late will disease and ear height. But, they were
increased under low nitrogen level for number of ears I plant ,ear length ,ear diameter
and silking date. Heritability was higher under the high nitrogen level for all trails except
number of ears/plant and silking date.The higher values over Ihe two nitrogen levels
were obtained for silking date (89.20%) and grain yield (85.10%). The expected gain from selection was higher under low nitrogen level for all
traits except resistance to late wilt disease and plant and ear height. The expected gain from selection showed that 51 families selection would be
effective for increasing Ihe grain yield (28.10%) in eyele-t (or the new synthetic variety
Sakha-6. Correlation coefficients between all studied traits with grain yield were
significant, indicating that the indirect selection for linked traits with yield would be
useful and effective for improving grain yield.