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Perennial ryegrass (Lolium perenne L.) provides a cost-effective forage species for New Zealand farms. Vegetative persistence (maintained herbage growth and survival without reseeding) is an important trait for decreasing costs of pasture establishment. Breeding for vegetative persistence is difficult because of a deficiency of long-term trials to observe the complex interactions between plant genotype and environment. Over time in a long-term trial, a shift in the genetic mean of a cultivar could occur as plants with genetically enhanced persistence traits survive. This study aimed to identify a shift in the genetic mean of two cultivars sown in a long-term trial in Hawkes Bay, New Zealand. Plots of 1 m rows were assessed in a trial for 13 months to compare changes in additive genetic variation ( σ a 2 ), narrow-sense heritability ( h n 2 ), and trait associations of half-sib (HS) populations generated from "Persistent" plants and commercially bought seed of "Original" cultivars Grasslands Samson and Commando. Significant (P < 0.05) σ a 2 and high levels of h n 2 for some populations were identified for scores of herbage growth, leaf width, plant habit and aftermath heading. This study found genetic shifts over time were cultivar specific. Traits that were different between Persistent and Original populations were previously associated with decreased pasture intake. Trait associations and cluster analysis identified HS families that could be used for developing enhanced persistence. [ABSTRACT FROM AUTHOR]

The objective was to evaluate water‐soluble carbohydrate (WSC) and crude protein (CP) concentration of perennial ryegrass (PRG) cultivars with different genetic potential for producing WSC under two contrasting agronomic managements in temperate climate (southern Chile). A 4 × 2 factorial design was randomly allocated to 24 plots (31 m2 each, three blocks): four PRG cultivars (diploid standard cultivar, "2nSt"; tetraploid standard cultivar, "4nSt"; diploid high sugar cultivar developed in New Zealand, "2nHSNZ"; and tetraploid high sugar cultivar developed in Europe, "4nHSEU") and two agronomic managements ("favourable," defoliations at three leaves per tiller and nitrogen (N) fertilization rate of 83.3 kg N ha−1 year−1; "unfavourable," defoliations at two leaves per tiller and N fertilization rate of 250 kg N ha−1 year−1). Herbage samples were collected in early spring, spring, summer and autumn. Concentration of WSC did not differ among cultivars in spring and summer, averaging 194 and 251 g/kg DM, respectively. The cultivar 4nHSEU had the greatest WSC concentration in early spring and autumn (187 and 266 g/kg DM, respectively) and the greatest CP concentration across samplings (average 230 g/kg DM). Favourable management improved WSC concentrations in early spring and summer and decreased CP in spring, summer and autumn. Annual DM yield did not vary with cultivar or management, averaging 8.43 t/ha. Within a 12‐month study at one site in a temperate environment in southern Chile, PRG cultivars have not shown a consistent expression of the "high sugar" trait, where a genetic × environment interaction might be operating. [ABSTRACT FROM AUTHOR]