Genetic variation and correlation among yield and quality traits in cocksfoot (Dactylis glomerata L.)

Abstract

SUMMARYThe objective of the present research was to study the genetic variability for total dry matter (DM) yield, tiller number, heading date and three quality traits, namely content of digestible dry matter (DDM), water-soluble carbohydrate (WSC) and crude protein (CP), in cocksfoot (Dactylis glomerata L.). Twenty-five parents were randomly chosen from a genetically broad-based population, and their respective half-sib (HS) families were generated. Clonally-propagated parents and their HS family seeds were grown as individual plants using a randomized complete block design with two replications in Alborz Research Center, Karaj, Iran, during 2002–04. The results of combined analyses over 2 years showed significant variances between clonal parents for all traits except CP. In the HS generation, between-family variances were only significant for tiller number, heading date and WSC. Clone×year (S2GY) and family×year (S2FY) interactions were significant for all traits except for WSC in HS families. The estimates of broad-sense heritability (h2b) were moderate to high for all traits (h2b=0·37–0·69), except CP. Narrow-sense heritability (h2n) estimates from analyses of progenies and from regression of HS progenies on parents (h2op) were moderate, relatively the same values as h2b for heading date, tiller number and WSC, which suggested that additive genetic variance was the main component controlling these traits. For DM yield and DDM, h2n and h2op estimates were low, whereas h2b estimates were moderate, which suggested that both additive and non-additive gene effects played an important role in the genetic regulation of these traits. Genetic correlations among CP with both WSC and DDM were generally negative, whereas WSC was positively correlated with DDM and tiller number. The genetic correlation among DM yield with DDM was weak and inconsistent and, in general, negative. DM yield had negative and positive correlation with heading date and tiller number, respectively. It was concluded that there was significant variation and moderate heritability for most traits in the cocksfoot populations evaluated to improve yield and quality traits. Selection for high WSC is a means to improve quality in general. The data also indicate that response to combined selection for both DDM and DM yield should be possible. Selection for DDM alone could result in reduction in yield.

Analysis of diversity and relationships among orchardgrass (Dactylis glomerata L.) accessions using start codon-targeted markers

“…Orchardgrass is an economically important and extensively used cool-season forage grass in China and in many other countries with temperate and cold climates (Sanada et al, 2010;Xie et al, 2012). It has been widely used as forage on nearly every continent because of its high yield, good nutrition, adaptability, and shade tolerance (Jafari and Naseri, 2007;Sanada et al, 2007;Xie et al, 2010). Orchardgrass is one of the top 4 perennial forage grasses grown in North America, Oceania, Europe, and Asia (Lindner and Garcia, 1997;Gauthier et al, 1998;Hirata et al, 2011), and it plays an important role in the livestock industry and in the sustainable development of environments worldwide.…”

Environmental and Genetic Variation for Water Soluble Carbohydrate Content in Cool Season Forage Grasses

“…Strong negative phenotypic and genotypic correlation between WSC and CP were obtained by Jafari (1998), Jafari et al (2003 in ryegrass, Jafari and Naseri (2007) in cocksfoot, Jafari and Javarsineh (2005) in tall fescue. However, Sanada et al (2007) obtained weak negative phenotypic and genotypic correlation between two traits in cocksfoot (Table 3).…”

“…Bugge (1978), in Italian ryegrass, and Clements (1969), using canarygrass, found no significant correlation between DMD and WSC. Strong positive phenotypic and genotypic correlation between WSC and DMD were obtained by Jafari (1998), Jafari et al (2003) in ryegrass, Jafari and Naseri (2007) in cocksfoot, Jafari and Javarsineh (2005) in tall fescue ( …”

“…Grusea and Oprea (1994) found h 2 b estimates for WSC of 0.58 in cocksfoot. Jafari and Javarsineh (2005) in tall fescue and Jafari and Naseri (2007) in cocksfoot estimated relatively moderate to high values of h 2 b, while h 2 n estimates were low suggests that genetic variation in this trait is controlled by both additive and non additive gene action. Sanada, et al (2007) in cocksfoot found significant genetic variation and moderate h 2 n estimates, and suggested that forage quality of cocksfoot was influenced by an additive gene effect and could be improved genetically by recurrent and phenotypic-genotypic selection ( …”

Analysis of variability, heritability, and genetic advance in seed yield and related traits of orchardgrass (Dactylis glomerata L.) populations

“…Thus, genetic variability existing in the available domestic populations or the collections for seed yield and related traits is an important resource in developing new plant cultivars that have desired agronomic and economic traits; in particular, it is very important for the related traits that cause increases in both seed and forage production simultaneously (Singh et al, 1991). Partitioning of total variation into genetic and environmental sources and their interactions is essential to assess genetic or environmental effects on seed yield and its components, as reported in a range of forage species (Rognli, 1987;Jafari and Naseri, 2007).…”