Selection for crude protein content in Phalaris tuberosa L. I. Response to selection and preliminary studies on correlated responses

Abstract

In a highly variable breeding population of P. tuberosa, marked responses were obtained to three generations of selection for high and low crude protein concentration (percentage nitrogen x 6.25) in whole tillers at heading. Total response was similar in each direction, and realized heritability estimates were h2 = 0.25 and h2 = 0.20 in the high and low directions respectively. The responses were accompanied by positively correlated changes in in vitro digestibility and in characters commonly used as indicators of nutritive value of herbage. However, there were large negatively correlated changes in seedling vigour, relative growth rates, and other morphological and physiological characters. The implications of the results for pasture plant breeding are discussed.

Germplasm and Cultivar Development

“…Despite this knowledge, reports of actual genetic progress in breeding for improved forage digestibility of cool-season forage grasses are limited to orchardgrass (Breese & Davies, 1970;Saiga, 1983;Rind & Carlson, 1988), perennial ryegrass (Humphreys, 1989b), smooth bromegrass (Ehlke et aI., 1986;Carpenter & Casler, 1990), and timothy (Surprenant et aI., 1990). Successful selection for crude protein concentration resulted in positive correlated selection responses for in vitro digestibility (Clements, 1969). Divergent phenotypic selection for neutral detergent fiber concentration, the single best laboratory predictor of intake potential (Van Soest, 1982), was successful in smooth bromegrass (Carpenter & Casler, 1990) and reed canarygrass (Surprenant et aI., 1988).…”

Prospects for improving the nutritive value of temperate, perennial pasture grasses

“…The decline in protein is slower in leaf than in stem. In P. aquatica, protein content is closely correlated with digestibility during plant growth from heading to seed dispersal and tiller death (Clements 1969). At the heading stage, protein content shows significant heritable variation (Clements 1969(Clements , 1973a.…”

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

“…Significant positive correlations between digestibility and WSC concentration in tall fescue forage have been reported (Burns and Smith, 1980). 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 ( …”