Variability in a silage maize “Zea Mays, l.” base population via two types of families [electronic resource]: 3. forage botanical composition and dry matter partitioning

Includes bibliographic reference

The base population for the recent study which is a yellow seed synthetic variety of maize was provided by Dr. M. Abd El-Sattar Ahmed,
professor of crop science, Crop Science Department, faculty of Agriculture, Egypt. Two types of families had formulated, as a step
before selection for high yielding ability. Those were half-sib (H.S) families and the first generation of self-pollination (S1) families.
Variability in the base population gene pool had estimated depending on vari-ance components of the families. Reduction in mean values
associated with S1 families relative to half-sib families reached 0.182, 1.18, 0.98, 3.88, 2.75 and 5.72% for leaves percentage,
stem percentage, ear percentage, grain percentage, cob per-centage and husk percentage, respectively. Genotypic variances among S1 families
was larger in magnitude than the respec-tive value for half-sib families in each measured botanical composition and dry matter partitioning
characters. Meanwhile, within family’s variance, (?2f), environmental variances (?2e) had reduced in S1 families relative to half-sib families
in each measured character. Genotypic variation among half-sib and S1 families were less than 20% of the studied botanical compo-sition
and dry matter partitioning characters mean values, except for cob percentage and husk percentage that had a genotyp-ic variation amount
to 24% and 26%, respectively. The estimates of additive variance (?2A) were positive for all studied botanical composition and dry matter
partitioning characters. While, the estimates of dominance variance (?2D) were nega-tive for all characters, the ratio of ?2A/?2G indicated
that additive genetic variance was more effective in controlling all stud-ied botanical composition and dry matter partitioning characters.
Estimates of heritability were higher in magnitude when calculated from first selfing generation (S1) compared to half-sib families,
for all studied characters. Stem percentage ex-pressed the least estimate heritability among all studied characters in each family type
(0.798 and 0.414 for half-sib and S1 families, respectively). This might indicate the influence of environment in the expression of that character.
Meanwhile husk percentage had highest genetic control expressed on heritability estimates from the two studied types of families.

Summary in Arabic