Inheritance of the concentration of water‐soluble carbohydrates and its relationship with the concentrations of fibre and crude protein in herbage of cocksfoot (Dactylis glomerata L.)

Abstract

The concentration of water-soluble carbohydrates (WSC) of cocksfoot is lower than that of other temperate grasses. Increasing in the WSC concentration in cocksfoot is important in increasing its digestibility and preference by ruminants. The genetic variation in mono-and disaccharides, fructans and total WSC concentrations and their interrelationships with crude protein (CP) and fibre concentrations of cocksfoot (Dactylis glomerata L.) at the vegetative growth stage in half-sib cross populations were assessed in two experiments conducted under spaced-planting and sward conditions.There was a wide range in the means for concentrations of fructan, WSC and neutral-detergent fibre (NDF) in parents and progeny whereas there was a narrow range of the means for concentrations of mono-and disaccharides, CP and acid-detergent fibre (ADF). Mean concentrations of mono-and disaccharides showed the smallest range.Mean squares of entries in parents and progenies were significant for mono-and disaccharides, fructan and total WSC concentrations in all populations. The entry × year interactions for fructan and total WSC concentrations were significant in parents and half-sib progeny. However, the entry × year interactions for mono-and disaccharide concentrations in progeny were not significant. Concentration of WSC was under genetic control since mean squares of the concentration values were significant and variance components for all traits were significantly larger than zero. There were negative genetic correlations between WSC and ADF and NDF concentrations. Narrow sense heritabilities (h n ) estimated from variance components of progeny for total WSC concentrations were 0.59 and 0.53 in sward and space-planting conditions, respectively.The h n of fructan and WSC concentrations were similar in both sward and spaced-planting conditions, whereas that of mono-and disaccharide concentrations varied from 0.20 to 0.69. It was found that the genetic variation of total WSC concentration in cocksfoot depended mainly on genetic variation in fructan concentration. These results suggested that the forage quality of cocksfoot at the vegetative growth stage was influenced by an additive gene effect and could be improved genetically by recurrent selection.

Research on Fructan in Wheat and Temperate Forage Grasses in Japan

“…Degradation of fructan also occurs following defoliation such as cutting 27 . Studies on the ecotypes of orchardgrass showed a significant correlation between fruc- tan concentration in autumn and winter hardiness 18 . Transgenic perennial ryegrass plants expressing wheat 1-SST and 6-SFT exhibit an increased level of fructan accumulation as well as an increased level of freezing tolerance 5 .…”

Cocksfoot

“…The correlation of forage yield with neutral detergent fiber (NDF) concentration was positive and, consequently, with in vitro dry matter digestibility (IVDMD) was negative (Stratton et al 1979) but the situation is not always clear-cut (see Casler et al 2002). The magnitude of the genetic correlation coefficient between WSC and forage yield under sward (Sanada et al 2007a) and spaced-plant conditions (Jafari and Naseri 2007) was low, while a positive correlation of acid detergent fiber (ADF) and NDF concentrations with forage yield was found among half-sib families in cocksfoot (Sanada et al 2007a). These results suggest that it may be possible to improve the forage quality without decreasing forage yield.…”

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

“…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 ( …”

“…They suggested at least three locations and 2 sowing years is necessary for evaluation of perennial ryegrass trials. Sanada, et al (2007) in cocksfoot reported a significant genotype × year interaction for WSC and suggests that the evaluation of forage quality traits should be carried out by divergent selection under multiple environments, especially for the evaluation of parental clones. Jafari and Rezaeifard (2010) in tall fescue found non significant genotype × phenological stage interaction effect for WSC.…”

“…However, Sanada et al (2007) obtained weak negative phenotypic and genotypic correlation between two traits in cocksfoot (Table 3). In summary, data in Table 3 show a consistent negative correlation between WSC and CP at both phenotypic and genotypic levels and over various herbage species.…”