Forage quality of white clover (Trifolium repens L.) × Caucasian clover (T. ambiguum M. Bieb.) hybrids and their grass companion when grown over three harvest years

Abstract

Forage quality of white clover (Trifolium repens L.) · Caucasian clover (T. ambiguum M. Bieb.) hybrids and their grass companion when grown over three harvest years Abstract Interspecific hybrids between white clover (Trifolium repens L.) and Caucasian clover (Trifolium ambiguum M. Bieb.) have been developed to introgress the rhizomatous growth habit into white clover, to increase persistence and drought tolerance. The forage quality of T. repens, T. ambiguum and the backcross 1 (BC1) and backcross 2 (BC2) hybrids and companion grass, when grown in mixtures with an intermediate perennial ryegrass (Lolium perenne L.) under a cutting-only management, was measured. In vitro dry-matter digestibility (DMD), water-soluble carbohydrate (WSC) and crude protein (CP) concentrations of the legume and grass fractions were measured throughout the growing season over three harvest years. Trifolium repens had a lower WSC but a higher CP concentration than the perennial ryegrass companion in all harvest years and at all cuts. The legume fractions from the BC1 and BC2 hybrid plots had a higher WSC and a lower CP concentration but an in vitro DMD value comparable with white clover throughout the growing season and in each harvest year. The grass fractions from the mixtures with the backcross hybrids had a higher WSC and a lower CP concentration than the grass fraction from the T. repens plots, in all harvest years and throughout the growing season. No difference in in vitro DMD between parental species and backcross hybrids was observed. The implications of these results for the development of these hybrids and animal performance are discussed.

Achievements and Challenges in Improving Temperate Perennial Forage Legumes

“…As considered in Section III, Caucasian clover is a very persistent and grazing-tolerant species (Taylor, 2008), as it grows and spreads within the sward by means of underground stems (rhizomes). The development of interspecific hybrids between white clover and Caucasian clover has been reported by a number of authors (Marshall et al, 2004;Williams and Nichols, 2011). Abberton and Marshall (2005) summarized the introgression of the rhizomatous trait from Caucasian clover into white clover to increase the grazing tolerance of large leaf types.…”

“…For this latter breeding target, a backcrossing program has produced selection lines that combine the agronomic characteristics of white clover with increased seed yield due to increased inflorescence production . Tetraploid T. ambiguum material has been used for introgressing the rhizomatous trait into white clover, producing selection lines with greatly enhanced drought tolerance in comparison with its white clover parent and control varieties (Marshall et al, 2001;Widdup et al, 2003), as well as improved forage quality characteristics (Marshall et al, 2004). The potential of interspecific hybrids between white clover and T. uniflorum to improve drought tolerance has also been carried out (Williams, 2014).…”

“…White clover has outstanding digestibility and protein content, and relatively low levels of water soluble carbohydrate (WSC) (Beever, 1993;Marshall et al, 2004). However, studies suggest that the high protein content of white clover may contribute to the inefficient utilization of nitrogen in mixed forage in the rumen that leads to pollution problems, such as the release of greenhouse gases and ammonia volatilization (Waghorn and Caradus, 1994).…”

“…A current target of the IBERS white clover breeding program is to quantify the extent of white clover genetic variation for protein content with a view to developing varieties with a protein content that better matches the energy supply of the companion grass. In related research, Marshall et al (2004) quantified the forage quality characteristics of interspecific hybrids between white clover and T. ambiguum and showed that the backcross hybrids had a higher WSC content, lower N and comparable digestibility. The authors suggested that this represented potential improvements of the behavior of white clover as a legume grown with grass for both grazing and silage.…”

Breeding for genetic improvement of forage plants in relation to increasing animal production with reduced environmental footprint

“…Major advances are being made in the development of improved varieties of forage grasses and legumes that are better adapted to likely climate change scenarios such as increased soil moisture deficit (Humphreys et al, 2006 and2011). To this end novel drought-tolerant forage varieties are currently under development by transferring drought resistance from fescue species into perennial ryegrass (Humphreys et al, 2006;Durand et al, 2007) and into white clover from closely related Trifolium ambiguum while maintaining forage quality (Marshall et al, 2004;Abberton and Marshall, 2005). An alternative approach is to use currently available varieties of species such as tall fescue, cocksfoot and timothy that are more drought tolerant than perennial ryegrass and can produce high forage yields but are currently generally of inferior quality.…”