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Crop Science Abstract -

Heritability and Correlations of IVOMD, Maturity, and Plant Height in Rhodes Grass1


This article in CS

  1. Vol. 18 No. 5, p. 847-850
    Received: Nov 4, 1977

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  1. K. H. Quesenberry,
  2. D. A. Sleper and
  3. J. A. Cornell2



Little information is available on variability and heritability of forage quality and digestibility in Rhodes grass (Chloris gayana Kunth). In this study, variability and heritability of in vitro organic matter digestibility (IVOMD) at 2 and 6 weeks of regrowth of 82 randomly selected plant introductions of Rhodes grass were examined in two growing seasons. The genotypic source of variance for 2 and 6 week regrowth digestibility was significant for both years. Mean IVOMD for 2 and 6-week regrowth over both years was 72 and 57%, respectively. Although years were a significant source of variation for IVOMD, entries that ranked high for 6-week IVOMD in year 1 were also consistently high in year 2. Simple correlation coefficients between 2- and 6-week IVOMD in year 1 (r = 0.13) and year 2 (r = 0.35) although statistically significant (P < 0.01), were rather low. However, when the data were combined over years the correlation between 2-week and 6-week IVOMD was r = 0.58. In addition the genetic correlation between 2- and 6-week IVOMD from analysis of covariance of both years data was rg = 0.75 indicating that certain genes influenced both 2- and 6-week IVOMD. Broad sense heritability estimates of 2- and 6-week IVOMD over both years were 13.7 and 42.5% respectively.

Significant variability was also found for maturity and plant height in both years. A highly significant positive correlation was found between maturity and plant height in year 1 (r = 0.76) and year 2 (r = 0.71). Heritability estimates for maturity and plant height derived from data averaged over both years were 74.3 and 66.3%, respectively. There was also a highly significant positive correlation (r = 0.71) between 6-week regrowth digestibility and maturity.

Our results indicate that sufficient variability exists in this random sample of unselected Rhodes grass plant introductions to make selection for improved IVOMD feasible. Broad sense heritability estimates for IVOMD, maturity, and plant height were sufficiently high to suggest that relatively rapid initial progress could be made in selecting for these traits. The high positive correlation between 6-week IVOMD and maturity suggests that selection for late maturing genotypes with high IVOMD should be possible.

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