Genetic Variability for Cell Wall Constituents and Associated Quality Traits in Reed Canarygrass¹

Abstract

Forage dry matter intake potential by ruminants is negatively associated with its cell wall constituent (CWC) concentration. The objectives of this study were to estimate genetic variance components and determine combining ability and heritability of CWC percent, and other associated quality traits in reed canarygrass (Phalaris arundinacea L.). Genotypic correlations were computed between paired characters. Twelve heterozygous clones used in two 6 ✕ 6 diallels and progenies from 30 crosses were grown for 2 years at two locations with three replicates arranged in randomized complete blocks. One plot consisted of six plants on 91 cm spacing in a row. Infrared spectroscopy was used to determine CWC, acid detergent fiber (ADF), acid detergent lignin (lignin), silica, crude protein, and in vitro digestible dry matter (IVDDM). Separate predictive equations were necessary for each year, probably due to yearly differences in drying procedures of samples. General (GCA) and specific combining ability (SCA) were estimated least squares analysis for one harvest in 1976, two harvests in 1977, and for the mean of the three harvests.Mean squares for GCA were significant for CWC, ADF, and lignin. Mean squares for SCA were significant for CWC, ADF, lignin, crude protein, and IVDDM. Estimates of variance components due to SCA were nearly twice as large or larger than the variance components due to GCA for CWC, ADF, lignin, crude protein, and IVDDM, indicating the presence of large amounts of nonadditive genetic variance under noncompetitive, spacedplant conditions. Broad‐sense and narrow‐sense heritabilities for CWC were 0.81 and 0.26, respectively.Estimates of genotypic correlations suggested that: (i) CWC was strongly positively correlated with ADF and lignin and strongly negatively correlated with protein and IVDDM; (ii) ADF had the highest correlation with IVDDM and was closely followed by lignin and CWC, which agreed with other reports using laboratory procedures for estimating these traits; (iii) none of the quality components was strongly correlated with spaced‐plant yield of first growth.

Agricultural Fitness of Smooth Bromegrass Populations Selected for Divergent Fiber Concentration

“…The highly consistent and positive genetic correlation between NDF and forage yield in Years 1 and 2 is consistent with numerous previous studies (Casler, 1999; Han et al, 2001; Hovin et al, 1976; Marum et al, 1979; Surprenant et al, 1988). Across harvests, locations, and years, NDF concentration averaged 477 to 687 g kg −1 , averaging 593 g kg −1 for the entire study (Casler, 2002).…”

“…The results of this study suggest that these solutions are unlikely to result in large changes to the natural genetic correlation between NDF concentration and forage yield. Previous estimates of this genetic correlation range from 0.53 to 0.89 (Casler et al, 1990; Hovin et al, 1976; Marum et al, 1979) and these results suggest that this genetic correlation is not likely malleable by selection.…”

Global or Local? A Choice for NIR Calibrations in Analyses of Forage Quality

“…2-6 NIR reflectance spectroscopy was used to measure forage quality in genetics and breeding programmes. 7 This method even allows the efficient determination of organic matter digestibility of grass, hay or silage. 8,9 The key step for using NIR spectroscopy as an analytical technique for forage analysis is the compilation of a wide spectral library.…”

An assessment of the relative importance of specific traits for the genetic improvement of nutritive value in dairy pasture

“…The majority of studies have reported small negative correlations between yield and digestibility (e.g. Carlson et al, 1969;Hovin et al, 1976;Hill and Barnes, 1977;Marum et al, 1979;Tan and Tan, 1982). Others have reported little or no correlation between DMD and yield (Vogel et al, 1981;Ehlke et al, 1983).…”