Two semi-exotic maize (Zea mays L.) populations, ESALQ-PB1 x ENTRELACA
DO 1 (EE1) and ESALQ-PB1 x CRAVO 4 (EC4) were used to evaluate the eff
ects of inbreeding depression of important agronomic traits and the po
ssibilities to use them as sources of inbred lines. Two types of proge
nies (S-1 and full-sib) were used. The semi-exotic population EC4 had
higher means for plant height, ear height, ear diameter, stand, number
of ears per plot, ear yield and grain yield for both noninbred and in
bred progenies. Population EE1 had greater ear length and tassel branc
h number. The effects of inbreeding depression were more evident in EE
1 for all traits, except ear yield and grain yield. Estimates of inbre
eding depression were similar for both populations for ear and grain y
ield. The estimates per 1% increase in homozygosity were 0.85 for ear
yield and 0.71 g/pl for grain yield in EE1, and 1.20 for ear yield and
1.02 g/pl for grain yield in EC4. The expected means of a random samp
le of homozygous lines (A = mu + a) were smaller than the overall cont
ribution of the heterozygotes to the mean (d) for ear yield and grain
yield. Increasing homozygosity through continuous selfing and selectio
n against recessive deleterious genes would contribute to enhance the
agronomic pattern of inbred lines in both populations.