Location: Forage and Range ResearchTitle: Cultivar by environment effects of perennial ryegrass cultivars selected for high water soluble carbohydrates managed under differing precipitation levels Author
Submitted to: Euphytica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/22/2015
Publication Date: 12/1/2015
Citation: Robins, J.G., Lovatt, J.A. 2015. Cultivar by environment effects of perennial ryegrass cultivars selected for high water soluble carbohydrates managed under differing precipitation levels. Euphytica. 208:571-581. Interpretive Summary: We evaluated the effect of different precipitation/irrigation management on the expression of non-structural carbohydrates and agronomics in perennial ryegrass. We utilized three locations, two in the United Kingdom and one at Logan, UT. At the UT location, we included four separate irrigation levels to determine the effect of irrigation on trait expression. The perennial ryegrass varieties contained varying levels of non-structural carbohydrates. Our hypothesis was that the higher levels of non-structural carbohydrates would result in higher agronomic performance under water-limited conditions. Trait expression was strongly influenced by the growing environment. Hence, we did not identify varieties that uniformly possessed high trait values in each environment. Nevertheless, we did identify groups of varieties that consistently performed well in each environment. While the importance of the high non-structural carbohydrate trait was inconclusive, there was a marked tendency for the varieties with high non-structural carbohydrates to produce greater forage mass under limited irrigation.
Technical Abstract: Historic results of perennial ryegrass (Lolium perenne L.) breeding include improved disease resistance, biomass, and nutritional quality. Yet, lack of tolerance to water stress limits its wise use. Recent efforts to increase water soluble carbohydrate (WSC) content in perennial ryegrass may increase drought tolerance. Herein, we report results of a multi-year and location evaluation of differing precipitation/irrigation levels on genetic and genotype x environment interaction effects of various agronomic traits in perennial ryegrass. The study included two UK locations (Aberystwyth, Wales and Edinburgh, Scotland) and a Logan, UT, USA environment. The Logan environment included four supplemental irrigation levels in a line-source irrigation design. Data included herbage dry matter, dry matter digestibility, crude protein, and WSC, collected between 2011 to 2013. There were differences (P<0.05) among the included cultivars for each phenotype when evaluated across environments. There was observed genotype x environment interaction for each phenotype, which precluded the identification of the best cultivar over all environnments. Additive main effect and multiplicative interaction modeling allowed for grouping of the individual environments to mega-environments. The analysis identified three mega-environments for each phenotype: 1) the UK environments, 2) the two highest Logan irrigation levels, and 3) the two lowest Logan irrigation levels. Mega-environments designations corresponded to water stress, temperature, and inherent geographic/climate differences between the environments. The evidence for the potential of increased WSC to improve drought tolerance under water stress was inconclusive, but high WSC cultivars also exhibited high herbage production under the imposed water stress.