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Pasture seed samples that were harvested around 1917 in New Zealand were analysed for purity, Epichloë endophyte and insects. Samples consisted of 13 packets of seed varying from 2.2 to 15.0 g and comprising, Chewings fescue (Festuca rubra L.), cocksfoot (Dactylis glomerata L.), oat (Avena sativa L.), perennial ryegrass (Lolium perenne L.) and red clover (Trifolium pratense L.). These findings show that in the period prior to modern seed testing laboratories only four of the 13 samples (31%) could possibly have met today's seed certification standards as it relates to seed purity. When compared with published purities and weed content of seed of the era these samples appear typical. Endophyte testing on the four ryegrass seed samples and the ryegrass contaminants found in the Chewings fescue and cocksfoot samples showed sample-to-sample variation in endophyte infection from nil to 91%. One cocksfoot sample, most likely harvested from the Banks Peninsula, contained an Argentine stem weevil. Subsequent checking of entomological collection records also revealed specimens being present in the Wellington region from 1916. Together these occurrences precede the earliest published record for the species in New Zealand by ten years and suggest that it may have been widespread at that time. [ABSTRACT FROM AUTHOR]

The productivity of perennial ryegrass (Lolium perenne L.) is constrained by summer water deficit. We hypothesised that selection for desirable water relations traits might partially mitigate this constraint. Genotypes of a 1970s, and two recent ryegrass cultivars were grown in 55 cm tall pots for three months and exposed to moisture deficit for four weeks, then 66 plants were assessed for shoot (SDW) and root (RDW) dry weight, leaf elongation rate (LER), specific water use (SWU), leaf osmotic potential (OP), OP change, leaf relative water content (RWC), and gravimetric soil moisture. Among the 66 genotypes, SWU ranged from 935 ± 19 to 1754 ± 74 g H2O g–1 DM. In principal component (PC) analysis, PC1 indicated greater growth and lower SWU from greater soil water extraction as the common trait association among genotypes tested and ANOVA of PC scores indicated that recent cultivars outperformed the 1970s cultivar. PC2 indicated water saving by decreased LER and SDW, with increased RDW indicative of summer dormancy. PC3 associated more negative OP with improved SWU and RWC. This experiment demonstrates not only genotypic diversity for SWU but also diversity in trait associations determining SWU, which should be considered when investigating SWU, both in ecology and agronomy research. [ABSTRACT FROM AUTHOR]

In New Zealand, a commonly sown pasture combination is perennial ryegrass with white clover. The hydrothermal time model (HTT) was used to quantify germination under different temperature (T) and water potential (WP) conditions for white clover 'Nomad' and perennial ryegrass 'Stellar AR1'. Seeds were germinated in vitro under a range of T × WP combinations, and HTT models were fitted to germination time course data. Rapid germination of white clover under optimum T and WP was reflected by a much lower value for its HTT constant compared with perennial ryegrass (10.8 vs 80.7 MPa °C d). However, the lower base water potential for perennial ryegrass (−1.29 vs −0.495 MPa) and a higher threshold temperature for thermoinhibition (21.8 vs 18.3°C), meant that predicted perennial ryegrass germination was more resilient in warm dry conditions. HTT models can be used to assist decisions about the timing of perennial ryegrass and white clover sowing. [ABSTRACT FROM AUTHOR]

The objective of this study was to compare the effect of one or two applications of gibberellic acid (GA) or nitrogen (N) fertiliser on dry matter (DM) yield and composition of perennial ryegrass-white clover pasture. Pasture was treated with 0 or 8 g a.i./ha of GA and 0 or 50 kg/ha N fertiliser in a 2 × 2 factorial design in late winter and spring. One application of N fertiliser increased DM yield by increasing leaf mass and tiller density of perennial ryegrass while one application of GA increased DM yield by increasing perennial ryegrass and white clover yield. There was no DM yield response to two applications of GA, though two applications of N did increase DM yield. A single GA application in late winter increased fibre and reduced protein concentration in ryegrass. The use of GA to increase DM yield with reduced herbage protein concentration may have reduced environmental impact through reducing N intake of livestock. [ABSTRACT FROM AUTHOR]

In New Zealand vineyards, evolution of glyphosate resistance in perennial ryegrass (Lolium perenne) has been reported recently, and restricted translocation of glyphosate has been found in these resistant plants. Past research with other plant species has found that restricted glyphosate translocation is temperature dependent. Glasshouse dose-response experiments were conducted with resistant perennial ryegrass at different temperatures to investigate if this population becomes susceptible to glyphosate under cooler conditions. Glyphosate-susceptible plants (population SP) grown in either warm (average of 20 °C) or cool (average of 9 °C) temperatures following treatment with several rates of glyphosate responded similarly to the herbicide regardless of temperature. In contrast, plants of population J (glyphosate resistant) were significantly more resistant than population SP to glyphosate when treated under warm conditions, but at the cooler temperature, population J was as susceptible as population SP. Thus the mechanism of resistance in population J appeared to be suppressed under cool conditions, suggesting that application of glyphosate during winter might improve control of glyphosate-resistant perennial ryegrass infestations. [ABSTRACT FROM PUBLISHER]

Three quick tests were evaluated for detecting glyphosate-resistant biotypes of Italian ryegrass and perennial ryegrass. Biotypes of these two species were used that were 13.4 and 7.3 times more resistant to glyphosate, respectively, than susceptible biotypes when assessed using a sprayed pot study. One assay exposed germinating seeds of resistant and susceptible populations for 8 days to different concentrations of glyphosate. Measurements of reduction in seedling root growth gave an estimate of resistance magnitude of 10.8 and 8.9 for Italian ryegrass and perennial ryegrass, respectively, similar to that from the sprayed pot study. Two other assays were tested and were able to differentiate resistant and susceptible biotypes. One measured the relative levels of shikimic acid in leaves following exposure to glyphosate; four to seven times more shikimic acid accumulated in glyphosate-susceptible populations of Italian and perennial ryegrass than in resistant populations. The other assay involved growing tillers of the plants in glyphosate solutions and the results showed that at glyphosate concentrations of 10 and 40 mg/L, the plantlets of resistant plants showed negligible visual injury and growth reduction compared with susceptible ones. Results obtained from these assays were not affected by whether the glyphosate formulation used was an isopropylamine salt or potassium salt. [ABSTRACT FROM AUTHOR]

Liveweight production was quantified from six dryland pastures at Lincoln University, Canterbury, New Zealand, over an 8 year period. The experiment was a randomised complete block with six replicates. The pastures were established in autumn 2002 with cocksfoot (CF) and subterranean (CF/Sub), balansa (CF/Bal), white (CF/Wc) or Caucasian (CF/Cc) clovers, a perennial ryegrass/white clover (RG/Wc) control and a lucerne (Luc) monoculture. Liveweight (LWt) production from Years 2 (2003–04) to 9 (2010–11) was 7940 kg LWt/ha from the lucerne monoculture, 7270 kg LWt/ha from the CF/Sub pasture and 5680 ± 171 kg LWt/ha from CF/Bal, CF/Wc, CF/Cc and RG/Wc pastures. Annually, LWt production ranged from 443 kg/ha (CF/Wc pastures with hoggets grazing in spring in 2006–07) to 1285 kg/ha from CF/Sub pastures in Year 9 when ewes with twin lambs at foot grazed in spring. On average, grass-based pastures produced 64%–70% of their total annual LWt production in spring compared with 57% from lucerne monocultures. In spring, relationships between LWt and total spring DM yield showed that 7.3 ± 0.68 kg LWt/ha was produced per 100 kg total DM (R2= 0.87) grown in 5 of the 6 years under the hogget/weaned lamb grazing system. Relationships between LWt and metabolisable energy or N yield failed to improve this relationship, which suggests that DM yield from persistent improved pasture components was the major factor responsible for differences in LWt production from these optimally grazed pastures. [ABSTRACT FROM PUBLISHER]

Genetic control of herbage yield—a complex trait of fundamental importance to agricultural productivity—was characterized in a perennial ryegrass biparental mapping population (I×S). Seasonal and combined growth score estimates of herbage yield (GS) were obtained from a trial conducted at three sites in New Zealand, over 2 years. Twenty-nine quantitative trait loci (QTL) for GS were identified on an I×S genetic linkage map constructed using simple sequence repeat (SSR) markers. Most QTL explained less than 15% of the phenotypic variation. QTL consistency was low among and within trial sites and years but 17 QTL were observed in more than one environment or season. QTL on linkage groups (LG) 1, 2, 4 and 6 were most consistent, based on numbers of QTL co-located at these positions and persistence of their allelic effects. SSR markers from consistent QTL positions may be beneficially applied in marker-assisted selection to enhance genetic gain for herbage yield in ryegrass breeding. [ABSTRACT FROM PUBLISHER]

The plant growth regulator trinexapac-ethyl (TE) is widely used to enhance ryegrass seed yields by reducing lodging (i.e. delaying collapse of the crop). However, lodging data are usually a single evaluation related to TE rate for a particular date of measurement. In eight field trials with varying rates of TE, weekly lodging assessments were made from full head emergence and days to 50% lodging were determined. In all trials, dynamic assessment of TE treatment showed there was a strong positive correlation (R 2 = 0.82) between the number of days to 50% lodging and seed yield. Nil TE reached 50% lodging in 7 days compared with 33 days for TE treatments of 400 g ha-1. On average, one days' delay in reaching 50% lodging increased seed yield by 24 kg ha-1 (response range 16-33 kg ha-1). The data indicate that TE rate per se is less important than the rate required to delay the date that 50% lodging is reached. The seed yield response was linear for delayed lodging from full head emergence to harvest, suggesting that the highest yields are achieved if the crop is not more than 50% lodged at harvest. [ABSTRACT FROM AUTHOR]

The effects of one cycle of selection for adventitious root system shape (i.e. percentage of total root mass in successive depth increments) were investigated in progeny of four perennial ryegrass pools with contrasting rooting patterns: (1) low surface (0-10 cm) root mass and roots to 1 m; (2) high surface root mass and roots to 1 m; (3) high root mass 10-20 cm and roots to 1 m; (4) high surface root mass, shallow rooting. Ten half-sib families were selected from each of the root type progenies, and five seeds from each family were sown and raised as stock plants. Tiller cuttings of each plant were planted into individual 1 m deep root screening tubes of sand and irrigated with nutrient solution After 115 days, the shoots were cut off, the sand/root column cut into 10 cm increments and the roots washed free of sand. The shoots and root samples were oven-dried and weighed. The four root shape progeny groups did not differ significantly for shoot or root dry weight (DW), or root/shoot DW ratio. Root type 2 (high surface root mass and roots to 1 m) progeny had a significantly higher percentage of total root mass between 0 and 10 cm than did root type 1 (low surface root mass and roots to 1 m) but none of the other differences were significant for percentage roots 0-10 cm. The root type 2 progeny had a lower percentage of total root DW between 10 and 20 cm than all the other root types, none of which differed and had a significantly lower percentage of root DW 20-30 cm than types 1 and 4 but did not differ at this depth from type 3 progeny. The probability of root type 4 (high surface root mass, shallow rooting) plants having roots at 1 m depth was 0.67; this was significantly lower than for the other selections, none of which varied significantly. These results indicate that it should be possible to change root system shape in perennial ryegrass using conventional breeding techniques. [ABSTRACT FROM AUTHOR]

Agronomic trials at cool (Gore) and warm (Palmerston North) temperate sites in New Zealand tested ten United Kingdom-bred (six diploids, four tetraploids) and two New Zealand-bred diploid ('Bronsyn', 'Impact') perennial and long-term hybrid ryegrasses (Lolium perenne, L. boucheanum) over two trial periods. Dry matter (DM) yields and persistence were better at the cool site but differential expression among cultivars for water-soluble carbohydrates (WSC) and yields was small compared with the warm site. The tetraploid cultivars generally had the highest concentrations of WSC but also on occasions had higher levels of crown rust, moderate DM yields and poorer persistence compared with diploids. Two of the tetraploid cultivars will be of value for their high WSC and good agronomic performance at the cool site. Some of the diploid UK cultivars expressed higher WSC and had similar or higher annual DM yields than some of the NZ-bred cultivars, and had high levels of resistance to crown rust. Overall, differences among cultivars in expression of WSC were small. Some differences occurred for seasonal DM yields with some UK cultivars having lower winter yields. [ABSTRACT FROM AUTHOR]

Root and shoot dry weights (DW), and root DW depth distribution were determined for wild type perennial ryegrass, breeding lines and cultivars. The plants were grown in 1 m deep tubes of sand culture in a glasshouse experiment. There were significant differences in shoot DW among accessions in the wild types but not within the bred material, and the wild types had more accessions with low shoot DW. Root DW varied significantly among accessions in both the bred material and the wild types. There were significant differences in root/shoot DW ratios among accessions, and between pools in the breeding lines, but no differences within the wild types. Root/ shoot ratios in the wild types had a much narrower and generally higher range of values than those in the bred lines. The percentage of root DW in the top 10 cm of sand did not vary significantly in the bred lines but it did in the wild types. Variation was recorded in root DW depth distribution at both the accession and genotype levels. We concluded that selection for merit based on shoot performance does not necessarily result in large root systems, and better plant performance might result from an increase in root system size in perennial ryegrass. [ABSTRACT FROM AUTHOR]

Interspecific hybridisation between tetraploid Lolium perenne L. (Lp) and L. multiflorum lam. (Lm) was investigated by using morphological genetic markers. Fluorescent-root and awned-floret phenotypes are dominant in Italian ryegrass (L. multiflorum), so seed-parent Italian ryegrass plants were emasculated to eliminate the possibility of self-fertilisation. The percentages of germination were 84.3% in LP x Lm and 90.6% in Lm x Lp crosses. The fluorescent seedlings were 81.8% in Lp x Lm and 83.7% in Lm x Lp crosses, and interspecific hybrids were 88.8 and 97.3%, respectively. The percentage of self-fertilisation was 4.0% in the perennial ryegrass. Pollen viability was 90.2% in the Lp x Lm and 91.0% in the reciprocal cross. The direction Lp x Lm seems to be a suitable method to produce interspecific hybrids on a mass scale. [ABSTRACT FROM AUTHOR]