midparent value

midparent value

the average value of a METRIC CHARACTER from two parents. Such values when compared with those of their offspring give a direct measure of NARROW-SENSE HERITABILITY.
References in periodicals archive ?
Genome(26.47%) was significantly lower than the midparent value (33.80 %), and increased gene expression in the heterotic hybrids was associated with its overall low genomic methylation level (Li et al., 2013).
However, the RIL distribution for boll size appeared to be shifted toward the smaller boll size of the NM24016 parent, as indicated by a RIL population mean that was lower than the midparent value (Table 4).
Therefore, in order to test whether this character is inherited in an additive fashion, the mean density on hybrid leaves was compared with the midparent value (mean of the two parents).
- In the absence of dominance, epistasis, and X-linked effects, the mean of the [F.sub.1] population is expected to equal the simulans-mauritiana midparent value. If X-linked loci have effects on the trait, the [F.sub.1] mean is expected to deviate in the direction of simulans because the X-chromosome in [F.sub.1] males is from simulans.
The progeny mean for this trait was similar to the midparent value. Approximately 57% of the progeny families had mean frequencies below the midparent value.
If differences in performance were determined additively, by genes acting independently without dominance or epistasis, performance in both the [F.sub.1] and [F.sub.2] hybrids should equal the midparent value (average performance of the two parent populations).
For each cross combination (P1 x P2), hybrid performance (HYB), midparent value (MP), absolute midparent heterosis (MPH), relative midparent heterosis (MPH%), and relative better-parent heterosis (BPH%) were calculated as follows: MP = (P1 + P2)/2; MPH = HYB-MP; MPH% = (MPH/ MP) x 100; BPH% = (HYB-Pmax)/Pmax x 100, where Pmax refers to the higher performing or taller parent.
The six variables used in the model to describe the phenotype were midparent value (m), additive effects [d], dominance effects [h], additive x additive interactions [I], additive x dominance interactions [j], and dominance x dominance interactions [1].
Heterosis was determined as MPH = ([F.sub.1] - MP)/MP, where [F.sub.1] is the [F.sub.1] hybrid performance, and MP = ([P.sub.1] + [P.sub.2])/2, the midparent value in which [P.sub.1] and [P.sub.2] are the performances of the inbred parents.
Similar patterns are found in figure 4, which plots a measure of |F.sub.2~ performance relative to the midparent value against distance.
The average oleic-acid content of [F.sub.1] seeds from reciprocal crosses (52 g [kg.sup.-1]) was very close to that of the standard low line A74/18/10 (Table 1) and much lower than the midparent value (387 g [kg.sup.-1]) indicating almost complete dominance of the standard low over the increased oleic acid content.