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Perennial ryegrass (Lolium perenne) plant breeding has delivered several high performing and broadly adapted cultivar‐endophyte (Epichloë) combinations for the New Zealand pasture‐based livestock industries. However, the trends in key traits and the potential economic value being added to farm systems have not previously been addressed systematically. Rates of gain in yield, nutritive value, phenological and morphological traits, and the economic value of those traits, were estimated among and within ryegrass functional groups (heading date, ploidy) traded commercially between 1973 and 2012. Whole pasture dry matter yield improvements of c. 80 and 60 kg DM/ha per year were identified in in late‐season heading diploids and tetraploids respectively. Trends in metabolisable energy were negative within functional groups, but positive when all cultivar‐endophyte combinations were included in the analysis due to the addition of tetraploids and late‐season heading diploids from the mid‐1990s. The estimated trend in overall economic value (all cultivar‐endophyte combinations included) was $7/ha per year based on DM yield only, about half the rate of gain previously estimated using small‐plot merit testing data. The trend increased to $15/ha per year when ME was included due to the emergence of commercial tetraploids from the early 2000s onwards. Estimated economic gains were high within late‐season heading diploids and tetraploids but not mid‐season diploids. These trends suggest that, if high performing cultivar‐endophyte combinations had been adopted in New Zealand dairy systems, then pasture utilization should have increased by ~1 t DM/ha above the current industry average. Reasons for this apparent discrepancy are discussed. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (PRG, Lolium perenne L.) breeding effort in New Zealand (NZ) has increased since c. 1990, resulting in greater functional trait diversity (e.g. heading date, ploidy, and associated Epichloë endophyte strain) in commercial products. This study quantified the variation, associations and interactions in dry matter (DM) yield, nutritive value and persistence‐related traits among commercial cultivar‐endophyte combinations released between 1973 and 2012, as a basis for assessing gains in value being delivered to the pasture‐based livestock industries. Twenty‐four or 28 combinations were compared over 3 years in two trials in each of two regions: Waikato in northern NZ (dryland), and Canterbury in central eastern South Island (irrigated). Cultivar‐endophyte combinations were sown in mixtures with white clover, and pastures were intensively grazed 8–11 times per year by dairy cows. Principal Component Analysis identified 4 distinct clusters for the DM yield variables and for metabolisable energy (ME) content in each of the four trials. A broadly‐adapted group of three late‐season flowering, AR37‐infected diploids with NZ and Spanish breeding backgrounds dominated the highest‐yielding clusters. Tetraploids dominated the high ME content clusters. Interactions with region were observed throughout the data set: the strongest of these was driven by endophyte strain effects in Waikato. High‐yielding cultivar‐endophyte combinations in these trials were also generally high‐yielding in the standard cultivar merit testing system operated in New Zealand, as interpreted via the DairyNZ Forage Value Index. However, alignment was poorer for medium‐ and lower‐yielding cultivar‐endophyte combinations. Several implications for forage evaluation methods and end‐user industries are identified. [ABSTRACT FROM AUTHOR]

The wheat sheath miner, Cerodontha australis Malloch (Diptera: Agromyzidae), is a small leaf‐ and stem‐mining fly that is native to New Zealand and eastern Australia where it feeds on grasses and cereals. Although not considered to be a major insect pest of pastures in New Zealand, it can be abundant during spring and summer in Waikato, New Zealand, and infests tillers of the introduced pasture plant, perennial ryegrass, Lolium perenne L. (Poaceae). Cerodontha australis is not deterred from feeding on L. perenne infected with commercially available strains of the fungal endophyte Epichloë festucae var. lolii, which have been shown to provide protection from a range of other insect pests. In this study, three‐pot trials and periodic examination over 18 months of field‐collected L. perenne tillers showed that two Epichloë endophyte strains, AR47 and AR48, reduced the survival and feeding damage by C. australis larvae, but there was no evidence of an effect on adult female feeding or oviposition. Compared to other strains of E. festucae var. lolii endophytes tested, plants infected with AR47 and AR48 had fewer and smaller larvae and less larval mining. The number of tillers with mining was reduced in AR47 relative to endophyte‐free (Nil) by 57.1% (ranging from 25.0 to 92.5% across trials) and in AR48 by 67.1% (26.3–100%). Larvae in AR47 and AR48 were found further from the base of the tiller where they were less likely to damage the meristem and cause tiller death. The number of larvae and pupae in pseudostems was reduced in AR47 and AR48 compared with Nil by 78.4 and 82.0%, respectively, in the field trial. Very few larvae survived to pupation in AR47 and AR48 plants, with a reduction compared to Nil of over 81.5% in AR47 and over 97% in AR48 in each of the four trials presented here. [ABSTRACT FROM AUTHOR]

Cerodontha australis Malloch (wheat sheath miner) is a leaf mining fly native to New Zealand and eastern Australia that feeds on grasses and cereals. It is thought to have limited economic impact despite being one of the most widespread and common insects in New Zealand pastures. In this study, data on C. australis were gathered over an 18‐month period from field plots of endophyte‐free Lolium perenne. Observations from pot trials on parasitism and other leaf miner species are also presented. Larval numbers were highest in late spring to early summer. One distinct peak per year of eggs and pupae indicated that this species may not be multivoltine, contradicting previous literature. Damage levels were high in spring/summer, with leaf mining in up to 53% of tillers sampled and, in mid‐summer, extending into the pseudostem in up to 41% of sampled tillers. Measurement of cephaloskeleton lengths confirmed that this species has three larval instars. Generally, only one larva per tiller survives to pupation, indicating density dependent regulation of populations, and larval/ pupal parasitism can reach high levels in summer. This study provides new information on the seasonal biology of C. australis, and its potential impact on L. perenne pastures in Waikato, New Zealand. [ABSTRACT FROM AUTHOR]

Limited persistence of perennial ryegrass (Lolium perenne L.) in dairy pastures is a significant issue in parts of New Zealand. The contribution of plant genetic background to this problem is not well understood. Temporal changes were investigated in genotypic and phenotypic composition of two perennial ryegrass cultivars (Nui SE and Alto AR37, older and newer cultivars respectively) sown as fields plots at three locations. Samples from survivor populations collected annually over 6 years from each location were established in a field nursery, analysed by simple sequence repeat (SSR) markers and assessed for vigour, leaf morphology and tiller number. SSR‐based estimates of the statistic G′ST indicated no significant (p >.05) genetic differentiation between survivor populations and plants grown from remnant seed (ex‐seed) after 5 years, and no significant change (p >.05) in within‐population genetic diversity for either cultivar at any location. SSR analysis of endophytic fungus (Epichloë festucae var. lolii) type revealed only limited ingress of off‐type ryegrass volunteers into plots at two locations. Vigour scores of survivor plants were not significantly (p >.05) different among plants collected from different locations and ex‐seed plants. Leaves on ex‐seed plants were longer (p <.001) than those on the survivor plants after four but not 6 years and may reflect a short‐term response to climatic conditions experienced in the field nursery. Our results suggest that the reported poor ryegrass persistence is not driven by changes in population genetic structure and that the sown cultivars survived and remained true to type. [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]

Grazed pastures based on ryegrass species provide most of the feed for dairy cattle in New Zealand. There are many cultivars of perennial ( Lolium perenne), annual and Italian ( L. multiflorum), and hybrid ( L. boucheanum) ryegrasses available for dairy farmers to use in pasture renewal. This study describes an index which ranks ryegrass cultivars relative to a genetic base according to the estimated economic value (EV) of seasonal dry matter ( DM) traits. A farm system model was used to derive EVs ($ ha−1 calculated as change in operating profit divided by unit change of the trait) for additional DM produced in different seasons of the year in four regions. The EV of early spring DM was consistently high across all regions, whereas EV for late spring DM was moderate to low. Genotype × environment analysis revealed significant reranking of DM yield among ryegrass cultivars across regions. Hence, separate performance values ( PVs) were calculated for two mega-environments and then combined with the corresponding season and region EV to calculate the overall EV for twenty-three perennial ryegrass and fifteen short-term ryegrass cultivars. The difference in operating profit between the highest ranked and lowest ranked perennial ryegrass cultivar ranged from $556 ha−1 to $863 ha−1 year−1 depending on region. For short-term ryegrasses used for winter feed, the corresponding range was $394 to $478 ha−1 year−1. Using PV for DM yield, it was estimated that plant improvement in perennial ryegrass has added $12-$18 ha−1 year−1 (depending on region) operating profit on dairy farms since the mid-1960s. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) infected with a novel endophyte ( AR37 or AR1), Wild-type endophyte or no endophyte (Nil) was sown with white clover ( Trifolium repens L.) in autumn 2005. The pastures were rotationally grazed by dairy cows from 2005-2009. Annual dry matter ( DM) yield did not differ but AR37 pastures had a higher ryegrass tiller density, especially after the 2008 summer drought (+130%), and less white clover than did AR1 pastures. Concentrations of alkaloids produced by the Wild-type association (lolitrem B, ergovaline) followed the same seasonal trends as did the AR37 alkaloids (epoxy-janthitrems) but summer drought reduced concentrations of lolitrem B and epoxy-janthitrems to less than half the mid-summer (February) peak concentrations in the other years. Insect pests were monitored annually between 2006 and 2009. Tiller damage by Argentine stem weevil ( Listronotus bonariensis (Kuschel)) was significantly reduced by all endophyte treatments. African black beetle ( Heteronychus arator (F.)) populations in soil samples increased during the experiment with Nil > AR1 > Wild-type = AR37. Root aphid ( Aploneura lentisci (Pass.)) infestations followed the pattern AR1 > Nil > Wild-type = AR37. A lower pest pressure from all insect pests in AR37 pastures is likely to have contributed to this treatment having the highest ryegrass tiller densities. [ABSTRACT FROM AUTHOR]