Germplasm and Cultivar Development

Abstract

Cool-season forage grasses have evolved, and continue to evolve, in natural ecosystems subject to environmental factors both in the presence and absence of human influences. The literature often lacks facts describing the evolution and domestication of forage grasses. Furthermore, the literature on this subject mainly deals with evolution of species in the broad scope, i.e., on a scale of hundreds of thousands or millions or years. Thus, some of our conclusions are necessarily speculative and are highly subject to the nature of the research that has been reported. We describe the forces of selection that act upon cool-season forage grasses and attempt to place each in historical perspective and in relation to each other. Because most economically important cool-season forage grasses are perennial, our principal focus will be on perennial species. There has been very little effort to quantify economic values of selection criteria or to empirically compare different breeding procedures in cool-season forage grasses. We attempt to summarize and compare some of the more important and thoroughly reported approaches used since the advent of formal breeding strategies in the late nineteenth and early twentieth centuries. These selection criteria and breeding procedures are as varied as the individual researchers who developed them. Examples are cited to illustrate principles and phenomena of historical or practical importance. More details of the agriculturally important species are discussed in the later chapters of this book. Space limitations prevent 1 Common names for plants have been used throughout the chapter. Refer to the appendix for the scientific name.

Adjustment of Biomass Yield to a Dry Matter Basis in Switchgrass Breeding: A Necessity or a Nuisance?

“…Breeders of perennial forages and energy grasses routinely use indirect selection, simply by using spaced plantings without interplant competition to conduct most breeding efforts. Selection for any measure of vigor or biomass in such an environment requires that "trait" to be correlated with forage or biomass yield on a sward-plot basis, a requirement that is seldom met (Casler et al, 1996;Wilkins and Humphreys, 2003). As such, forage breeding is notoriously inefficient compared with annual grain crop breeding (Casler, 1998;Casler et al, 1996;Wilkins and Humphreys, 2003).…”

“…Selection for any measure of vigor or biomass in such an environment requires that "trait" to be correlated with forage or biomass yield on a sward-plot basis, a requirement that is seldom met (Casler et al, 1996;Wilkins and Humphreys, 2003). As such, forage breeding is notoriously inefficient compared with annual grain crop breeding (Casler, 1998;Casler et al, 1996;Wilkins and Humphreys, 2003). Documented yield gains in forage crops are limited to a small number of species and indicate relatively slow progress toward increasing forage yield (Casler et al, 1996;Wilkins and Humphreys, 2003;Brummer and Casler, 2014).…”

“…As such, forage breeding is notoriously inefficient compared with annual grain crop breeding (Casler, 1998;Casler et al, 1996;Wilkins and Humphreys, 2003). Documented yield gains in forage crops are limited to a small number of species and indicate relatively slow progress toward increasing forage yield (Casler et al, 1996;Wilkins and Humphreys, 2003;Brummer and Casler, 2014). Part of the reluctance of forage-crop and energy-grass breeders to move toward sward-plot trials for measuring forage or biomass yield is the difficulty in generating selection intensities to rival those achievable in spaced plantings.…”

“…Part of the reluctance of forage-crop and energy-grass breeders to move toward sward-plot trials for measuring forage or biomass yield is the difficulty in generating selection intensities to rival those achievable in spaced plantings. One perception is that the high selection intensities that can be achieved in spaced plantings can overcome the relatively low genetic correlation between the target trait and the alternative trait, a concept that is absurdly false when the genetic correlation is near zero (Casler et al, 1996;Falconer and Mackay, 1996;Wilkins and Humphreys, 2003). The objective of this paper is to determine if sward-plot trials to measure biomass yield of switchgrass (Panicum virgatum L.) could be made more efficient and effective by eliminating the dry matter (DM) adjustment step in a breeding program.…”

The Fungal EndophyteEpichloë festucaevar.loliiDoes Not Improve the Freezing Tolerance of Perennial Ryegrass

“…Perennial ryegrass (Lolium perenne L.), used worldwide for both turf and forage, is particularly susceptible to winterkill (Hofgaard et al, 2003). As a result, improved winter hardiness has been an important breeding objective in perennial ryegrass breeding programs (Casler et al, 1996).…”