Polycross Genetic Analysis of Forage Yield and Related Traits in Dactylis glomerata

Abstract

Orchardgrass (Dactylis glomerata L.) is a long‐lived perennial forage grass and one of the main perennial grasses that naturally grow in temperate pasture and rangelands in northern and western Iran. This study was conducted to increase knowledge about the genetic basis of agro‐morphological traits in orchardgrass, which may help further improvement of this species. Half‐sib families derived from a polycross of 25 parental genotypes were evaluated during 2 yr, and 11 agro‐morphological traits together with two quality traits were measured. Families were significantly different for all the traits measured. Significant differences were also observed between the 2 yr of evaluation for all the traits except for mean percent of dry matter and panicle length. Narrow‐sense heritability ranged from 0.12 (number of fertile shoot) to 0.79 (mean percent of dry matter). The estimate of narrow‐sense heritability for the most economically important trait (total dry matter yield) was relatively low (0.17 to 0.30), showing that both additive and non‐additive gene effects played a role in the genetic control of this trait. In addition to a weak phenotypic correlation, total dry matter yield had a high genetic correlation with plant height and number of fertile shoots. No significant phenotypic correlation was observed between forage yield and crude protein, though a negative genetic correlation was evident. According to the results of heritability estimations and correlation between the traits, indirect selection for dry matter yield would be possible through selection for plant height.

Magnitude of inbreeding depression and genetic variation analysis of agro‐morphological traits in orchardgrass

“…Low heritability for NS in the OP population was in agreement with the findings of Majidi et al. () regarding families of half‐sibs of orchardgrass. As the variance among families of half‐sib means represents primarily additive genetic variance, the heritability value represents an estimation of narrow‐sense heritability () in the OP population (Nguyen and Sleper ).…”

“…Majidi et al. () also reported a positive and significant correlation between total dry matter yield and spread in Dactylis glomerata . As S had the highest heritability in all of the studied populations, indirect selection could be effective to improve the forage yield through spread.…”

“…Majidi et al. () estimated heritabilities based on parent–offspring regression, showing that it ranged from 0.15 for the number of fertile shoot to 0.65 for spread in orchardgrass.…”

Genetics of Inbreeding Effects in Smooth Bromegrass

“…Vogel et al (1980) maintained that estimation of heritability by parent-offspring regression would not be inflated in cases where parents and progenies were evaluated in different plots. Moderate to high estimates of heritability have been reported for spread in the OP progenies of smooth bromegrass (Araghi et al, 2014) and orchardgrass (Dactylis glomerata L.; Majidi et al, 2015). In the OP progenies, NS had narrow-sense heritability, which supports the claim that this trait is mainly under additive genetic control and that it would be effective to select for it.…”

Root characteristic system improves drought tolerance in orchardgrass

“…Half‐sib families derived from a polycross of 30 orchardgrass genotypes were used as genetic materials for this study (Table S1). During 2008, 15 Iranian and 10 foreign orchardgrass accessions (totally 25) were polycrossed and the seeds were grown in the field during 2010 and were evaluated for 2 years (for more information, see Araghi, Barati, Majidi, & Mirlohi, ; Majidi, Araghi, Barati, & Mirlohi, ; Majidi et al., ). Then, 30 single plants were randomly selected within the polycrossed population (within 25 half‐sib families), making a collection containing a total of 30 new parental genotypes.…”