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The study was carried out at the Field Experimental Station of the Russian State Agrarian University -- Moscow Timiryazev Agricultural Academy (Moscow, Russia) in two field experiments. In experiment 1 from 2017 to 2019, the authors studied the reaction of lawn grasses of the Dutch selection type to the operational load on the sod (trampling). Perennial ryegrass, red fescue, Kentucky bluegrass, and a three-component herbal mixture from these grass types were exposed to a low, medium, and high degree of operational load. In experiment 2 from 2003 to 2014, the authors investigated the resistance of Danish selection grasses in two- and four-component grass mixtures. In experiment 1, in the second year of life, single-species crops of perennial ryegrass, red fescue, and a three-component grass mixture formed dense grass stands with the number of shoots from 129 to 183 pcs/dm2. Kentucky bluegrass showed significantly inferior results, with the density of herbage not exceeding 53-66 pcs/dm2. In the third year of life, due to the lack of atmospheric precipitation, the density of all herbage, except for meadow bluegrass, decreased by a factor of 2.0-2.4. In 2017 (the first year of herbage life), the number of wild grasses was insignificant, amounting to 0.6-0.8 pcs/m2. In 2018, weediness increased to 3.3-5.6 pcs/m2 and in 2019, up to 6.1-9.5 pcs/m2. Lawn-type grasses had a low yield level, with the dry weight from 1.5 to 3.5 t/ha. On average, over 2 years, the grass mixture formed 45.1% more aboveground mass than single-species grass crops. In experiment 2, during the long-term operation of lawns from grasses of Danish selection, red fescue was the most stable in the composition of herbage. In the twelfth year of the life of grasses, its proportion ranged from 46.7 to 88.6%. The least long-lived species was the creeping bent, which dropped out of the agrophytocenosis in the eighth year of life. [ABSTRACT FROM AUTHOR]

Pot experiments were conducted to study the effects of different cadmium (Cd) levels (0, 75, 150, 300 and 600 mg kg−1) on the growth, cadmium concentration and cadmium accumulation of two varieties of ryegrass, and the correlation between plant cadmium concentration and soil cadmium chemical forms. The results showed that root dry weight of the two varieties of ryegrass, dry weight of shoot and plant in Aubade increased first and then decreased with the increase of soil cadmium. When the soil cadmium level was 75 mg kg−1, shoot dry weight and plant dry weight in Aubade reached the maximum (10.92 g pot−1 and 12.03 g pot−1), which was 11.13% and 10.67% higher than that of the control respectively. The cadmium form in shoot of the two ryegrass varieties was dominated by was sodium chloride extraction (F-NaCl), followed by deionized water extracted (F-W) and acetic acid extracted (F-HAC). The cadmium forms in soils were mainly exchangeable (EXC-Cd), and cadmium concentrations of leaf, stem and root were significantly positively correlated with exchangeable cadmium content in the rhizosphere soil (P < 0.01). The EXC-Cd content in Abbott soil was higher than that in Bond, which was consistent with Abbott's Cd absorption above Bond. The cadmium transport factor of the two ryegrass varieties were less than 1, and cadmium bioconcentration factor were all greater than 1. In comparison of the two ryegrass varieties, the dry weight of shoot and plant of Abbott were higher than that of Bond under the stress of 75–600 mg kg−1 Cd. The cadmium concentration and cadmium accumulation of shoot and root in Abbott were also higher than that of Bond. There was a genotypic difference in ryegrass tolerance to cadmium and cadmium absorption. Abbott was more suitable as a phytoremediation material for soil cadmium pollution. [ABSTRACT FROM AUTHOR]

Pot experiment was conducted to study the difference of cadmium uptake and OAS and IRT genes' expression between the two ryegrass varieties under cadmium stress. The results showed that with the increase of cadmium levels, the dry weights of roots of the two ryegrass varieties, and the dry weights of shoots and plants of Abbott first increased and then decreased. When exposed to 75 mg kg−1 Cd, the dry weights of shoot and plant of Abbott reached the maximum, which increased by 11.13 and 10.67% compared with the control. At 75 mg kg−1 Cd, cadmium concentrations in shoot of the two ryegrass varieties were higher than the critical value of Cd hyperaccumulator (100 mg kg−1), 111.19 mg kg−1 (Bond), and 133.69 mg kg−1 (Abbott), respectively. The OAS gene expression in the leaves of the two ryegrass varieties showed a unimodal curve, which was up to the highest at the cadmium level of 150 mg kg−1, but fell back at high cadmium levels of 300 and 600 mg kg−1. The OAS gene expression in Bond and Abbott roots showed a bimodal curve. The OAS gene expression in Bond root and Abbott stem mainly showed a unimodal curve. The expression of IRT genes family in the leaves of ryegrass varieties was basically in line with the characteristics of unimodal curve, which was up to the highest at cadmium level of 75 or 150 mg kg−1, respectively. The IRT expression in the ryegrass stems showed characteristics of bimodal and unimodal curves, while that in the roots was mainly unimodal. The expression of OAS and IRT genes was higher in Bond than that in Abbott due to genotype difference between the two varieties. The expression of OAS and IRT was greater in leaves than that in roots and stems. Ryegrass tolerance to cadmium can be increased by increasing the expression of OAS and IRT genes in roots and stems, and transfer of cadmium from roots and stems to the leaves can be enhanced by increasing expression OAS and IRT in leaves. [ABSTRACT FROM AUTHOR]

In order to understand the mechanism of the difference of Cd absorption and Cd enrichment in different ryegrass varieties, pot experiment was conducted to study on the response of two varieties of ryegrass (Bond and Abbott) to Cd stress as well as the differences of Cd uptake and expression of MT family genes and NRAMP2. Results showed that root dry weights of two varieties and shoot dry weights of Abbott increased first and then decreased with the increase of Cd level in soil. When exposed to 75 mg kg−1 Cd, shoot dry weight and plant dry weight of Abbott both reached maximum values (10.92 and 12.03 g pot−1), which increased by 11.09 and 10.67% compared with the control, respectively. Shoot dry weight and plant dry weight of Bond decreased with the increase of Cd level in soil. When the Cd level in soil was 75 mg kg−1, shoot Cd concentrations of the two varieties were 111.19 mg kg−1 (Bond) and 133.69 mg kg−1 (Abbott), respectively, both of which exceeded the critical value of Cd hyperaccumulator (100 mg kg−1). The expression of MT gene family and NRAMP2 in the leaf of Bond variety significantly increased at the Cd level of 75 mg kg−1 and reached maximum value (except MT2C) at Cd level of 150 mg kg−1. The expression of MT gene family in the stem of Bond variety showed a double-peak pattern, while the expression of NRAMP2 was a single-peak pattern. The expression of MT gene family and NRAMP2 in Abbott variety was consistent with single-peak pattern. The expression of MT gene family and NRAMP2 in leaf both significantly increased at Cd level of 150 mg kg−1, while that in stem and root significantly increased at Cd level of 75 mg kg−1. For both varieties of ryegrass, the expression amount of MT family genes and Nramp2 in leaf was higher than that in root and stem, indicating the Cd tolerance of ryegrass can be improved by increasing the expression levels of MT family genes and Nramp2 in stem and root. There was significant genotypic difference in the expression of MT gene family and NRAMP2 between the two varieties of ryegrass, and the expression of MT gene family and NRAMP2 in leaves and stems of Bond variety was higher than that in Abbott variety, while the expression of MT gene family and NRAMP2 in roots of Abbott variety was higher than that in Bond variety. The two gene families investigated in this study may be closely related to Cd uptake, but not related to Cd transport from root to leaf and Cd enrichment in shoot. [ABSTRACT FROM AUTHOR]

Leaf stage-dependent defoliation is linked to the plant's physiological status and may be a more suitable criterion than time-based intervals for harvesting forage grasses, but no reports of research with annual ryegrass ( Lolium multiflorum Lam. var. westerwoldicum) were found. To address this, a 2-year field study was carried out at Raymond, MS, on a Loring silt loam soil (fine-silty, mixed, thermic Typic Fragiudalfs). Forage production, morphological characteristics and nutritive value responses to defoliation based on leaf stage (2, 3 and 4 leaves per tiller) and two residual stubble heights ( RSH; 5 and 10 cm) of a tetraploid ('Maximus') vs. a diploid ('Marshall') cultivar of annual ryegrass were quantified. Forage harvested, in 2011, increased linearly as leaf stage increased from 7.3 to 8.8 Mg/ha, but during 2012 was least (7.0 Mg/ha) at 3-leaf stage and similar at the other two leaf stages (7.6 Mg/ha). Tiller density was less for Maximus (1,191 tillers/m2) than for Marshall (1,383 tillers/m2). Leaf blade proportion decreased with increasing leaf stage and was greater by 9% for Maximus than for Marshall. Generally, forage nutritive value became less desirable with increasing leaf stage. There was a dichotomy in forage harvested and nutritive value responses, but maximum forage productivity was achieved when annual ryegrass was defoliated at the 4-leaf stage interval. [ABSTRACT FROM AUTHOR]

To assess the genetic diversity and population structure of Lolium species, we used 32 nuclear simple sequence repeat (SSR) markers and 7 cytoplasmic gene markers to analyze a total of 357 individuals from 162 accessions of 9 Lolium species. This survey revealed a high level of polymorphism, with an average number of alleles per locus of 23.59 and 5.29 and an average PIC-value of 0.83 and 0.54 for nuclear SSR markers and cytoplasmic gene markers, respectively. Analysis of molecular variance (AMOVA) revealed that 16.27 and 16.53% of the total variation was due to differences among species, with the remaining 56.35 and 83.47% due to differences within species and 27.39 and 0% due to differences within individuals in 32 nuclear SSR markers set and 6 chloroplast gene markers set, respectively. The 32 nuclear SSR markers detected three subpopulations among 357 individuals, whereas the 6 chloroplast gene markers revealed three subpopulations among 160 accessions in the STRUCTURE analysis. In the clustering analysis, the three inbred species clustered into a single group, whereas the outbreeding species were clearly divided, especially according to nuclear SSR markers. In addition, almost all Lolium multiflorum populations were clustered into group C4, which could be further divided into three subgroups, whereas Lolium perenne populations primarily clustered into two groups (C2 and C3), with a few lines that instead grouped with L. multiflorum (C4) or Lolium rigidum (C6). Together, these results will useful for the use of Lolium germplasm for improvement and increase the effectiveness of ryegrass breeding. [ABSTRACT FROM AUTHOR]

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 wide 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/irrigations levels on genetic and genotype × environment interaction effects of various agronomic traits in perennial ryegrass. The study included two UK environments (Aberystwyth, Wales and Edinburgh, Scotland) and four USA environments located in Logan, UT and consisting in four supplemental irrigation levels in a line-source irrigation design. Data included herbage dry matter, dry matter digestibility, crude protein, and WSC, collected from 2011 to 2013. There were differences ( P < 0.05) among the included cultivars for each phenotype when evaluated across environments. There was observed cultivar × environment interaction for each phenotype, which precluded the identification of the best cultivar over all environments. 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. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) evaluation trials are often conducted under simulated grazing to identify the most productive cultivars. It is unclear whether simulated grazing identifies the most productive cultivar for animal-grazed swards. Ten cultivars were established as plots and managed concurrently under simulated grazing ( SG), animal grazing ( AG) and conservation ( CON). The experiment lasted 3 years with dry-matter ( DM) off-take, digestibility, tiller density and ground-cover score recorded in all years. A good relationship existed between DM off-take under SG and CON ( R2 = 0·73). The relationship between SG and AG was strongest in year 2 and 3 ( R2 = 0·53 and 0·55 respectively). High DM production was observed in SG swards in year 1; this was weakly related to the DM production of the AG sward. Across the 3 years, the CON treatment had higher yields than either of the other two treatments and was poorly correlated to DM yield under AG, confirming that cultivars should be evaluated under a similar defoliation frequency to their intended use. Tiller density declined quickest under CON and slowest under AG. Some reranking of cultivars occurred between defoliation managements. The results show that simulated grazing is a useful indicator of DM yield performance of animal-grazed swards. [ABSTRACT FROM AUTHOR]

Glyphosate effectively controls susceptible biotypes of numerous weed species, but applications are often injurious to turfgrass. 'Aurora Gold' hard fescue (Festuca longifolia Thuill.) and 'JS-501' perennial ryegrass (Lolium perenne L.) have enhanced tolerance to glyphosate compared with traditional varieties, but the mechanisms that convey tolerance are not well understood. The objectives of this research were to investigate the physiological basis for glyphosate tolerance in Aurora Gold hard fescue and JS-501 perennial ryegrass. In greenhouse experiments, the estimated glyphosate rate required to reduce dry shoot mass 50% from the nontreated shoots at 4 wk after treatment measured >3360, >3360, 1850, and 1310 g acid equivalent (a.e.) ha-1 for Aurora Gold, JS-501, 'Manhattan V' perennial ryegrass, and 'Stonehenge' hard fescue, respectively. Absorption of 14C-glyphosate was similar between hard fescue cultivars and averaged 5% of the applied radioactivity. However, Aurora Gold accumulated 20% less shikimate than Stonehenge when incubated at ≥250 μM of glyphosate in leaf disk assays. JS-501 perennial ryegrass absorbed less 14C-glyphosate than Manhattan V (13 vs. 22% of the applied) and accumulated ~50% less shikimate. All cultivars translocated the majority of absorbed radioactivity out of the treated leaf. Based on these findings, glyphosate has less target-site inhibition in Aurora Gold compared with a more susceptible hard fescue cultivar. The glyphosate tolerance of JS-501 perennial ryegrass involves two mechanisms including less absorption and target-site inhibition from a more susceptible cultivar. [ABSTRACT FROM AUTHOR]

The aim of this field study was to evaluate genotype x year interaction for spike length, 1000 seed weight, seed number per g and hectoliter mass in perennial ryegrass, using eight divergent genotypes across two growing seasons. Interaction was evaluated using AMMI (Additive Main Effects and Multiplicative Interaction) model. All traits schowed additive (genotype, year) and non additive (genotype x year interaction) variation. On the basis od AMMI1 biplot genotype G4 showed most stability for all examined traits, so it can be recommended for sowing in different environmental conditions. Also, the genotype G4 could be used in the creation of new local varieties of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) and Italian ryegrass ( Lolium multiflorum Lam.) are important temperate forage grasses which are closely related, generating fertile interspecific hybrids. All groups are represented by multiple cultivars in the commercial pasture seeds market. Due to the close taxonomic relationship between the two species, differentiation based on morphophysiological criteria is not always readily achievable. In addition, an obligate outbreeding reproductive habit produces high levels of individual heterozygosity and intrapopulation diversity, which presents problems for discrimination between cultivars. Molecular genetic marker polymorphism provides an effective means of addressing these challenges. An iterative process of resequencing from loci distributed across the perennial ryegrass genome was used to identify single nucleotide polymorphism (SNP) markers, which were then validated and formatted in a highly multiplexed (384-plex) assay system. SNP genotyping was then performed across samples of 48-192 individuals from a total of 27 ryegrass cultivars (19 of perennial ryegrass, seven of Italian ryegrass and one hybrid cultivar). SNP markers from perennial ryegrass exhibited a high level of transfer to Italian ryegrass. Data analysis permitted quantification of intra- and inter-species diversity, as well as discrimination between cultivars within each species, including diploid and autotetraploid cultivars of perennial ryegrass. Lower levels of SNP-based diversity were detected in Italian ryegrass than in perennial ryegrass. A neighbour-joining tree based on genetic distance analysis located a hybrid cultivar to an intermediate position between the two species-specific cultivar groups. The resulting catalogue of ryegrass cultivars will provide support for the processes of cultivar accreditation and quality assurance. [ABSTRACT FROM AUTHOR]

Determination of animal preference in the early stages of the evaluation process of new forages may provide insights into potential animal performance as well as plant responses to grazing. A 2-yr study was conducted at Raymond, MS, to determine grazing preference of cattle between tetraploid and diploid annual ryegrass (Lolium multiflorum Lam.) cultivars and its relationship with morphological and chemical characteristics. Treatments were two tetraploid cultivars, Maximus and Nelson, and two diploid cultivars, Marshall and Gulf, arranged in a 4 × 4 Latin square design experiment. Eight Angus crossbred yearling steers (Bos taurus) (initial body weight of 320 ± 19 kg) were used to determine grazing preference based on herbage disappearance, the Chesson-Manly (CM) index, and amount of time spent grazing. In both years, herbage disappearance was greater for the tetraploid (1380 kg ha-1) than diploid cultivars (895 kg ha-1), with greater CM index for the tetraploid than for the diploid cultivars (8.1 vs. 5.8% in Year 1 and 6.9 vs. 5.5% in Year 2). Also, animals spent about 10% greater time grazing the tetraploid than diploid cultivars during both years. During the first year, the tetraploid cultivars had less neutral detergent fiber (NDF) (556 vs. 589 g kg-1) and less acid detergent fiber (ADF) (341 vs. 359 vs. g kg-1) than the diploid cultivars and Nelson had greater watersoluble carbohydrate (WSC) concentration (184 g kg-1) than the other three cultivars (152 g kg-1). In the second year, NDF, ADF, and WSC were not different among cultivars. Tetraploid cultivars had a greater proportion of leaf than diploid cultivars. The results indicate that cattle showed greater preference for tetraploid cultivars, which appeared to be linked mainly with pregraze herbage mass and the proportion of leaf. [ABSTRACT FROM AUTHOR]

Abstract: The objective of the present study was to test the hypothesis that feeding dried grass from a ryegrass cultivar with high water-soluble carbohydrate (WSC) concentration to dairy cows lowers emissions of enteric methane and urinary nitrogen. This dried grass (here the cultivar ‘AberMagic’) was compared as a forage-only diet to dried grass prepared from a low-WSC cultivar (‘Respect’). Six mid-lactating primiparous Holstein-Friesian dairy cows (19kg milk/cow/day) were subjected to a change-over design in two 26-day experimental periods. In the last 8 days of each period, feed intake, milk yield, fecal and urinary excretion were recorded and samples were taken. During 2 days, methane emissions were measured in open-circuit respiration chambers. The dried grass type had no significant effect on feed intake and milk gross composition. Milk yield was lower for cows fed the dried high-WSC grass. Total enteric methane (g/day) did not significantly differ when cows received dried high-WSC grass (279) instead of dried low-WSC grass (315). Methane expressed as g/kg dry matter intake (19.4 and 20.3 for dried high- and low-WSC grass, respectively), and methane conversion rates (Y m ; 63kJ/MJ of gross energy for both dried grass types) were similar with both dried grass types. The dried high-WSC grass had a lower crude protein concentration compared to the dried low-WSC grass (158 vs. 255g/kg dry matter) resulting in a correspondingly different urinary N excretion (114 vs. 292g/day) and milk urea concentration. A similar effect was found for urinary N proportion of total excreta N. Fecal N excretion and milk N secretion were higher with the dried high-WSC grass. In conclusion, feeding dried high-WSC ryegrass, where WSC mainly replace crude protein, might be helpful in limiting N emissions from dairy cattle husbandry whereas methane emissions seem to remain unaffected. Further studies have to test whether dried high-WSC grass has the same effect when the WSC replace fiber and to address the extent to which favorable effects can be recovered in mixed forage-concentrate diets. [Copyright &y& Elsevier]

The selection and feeding of perennial ryegrass ( Lolium perenne L.) varieties (PRV) or perennial grass species (PGS) may affect enteric methane (CH4) output because of changes in the fermentation dynamics in the rumen as a result of differences in herbage chemical composition. The objective of this study was to determine the effects of PRV and PGS harvested throughout the growing season on herbage chemical composition, and in vitro rumen fermentation variables and CH4 output per unit of feed using a batch culture technique. Seven PRV (Experiment 1: Alto, Arrow, Bealey, Dunluce, Greengold, Malone, Tyrella) and six perennial grasses [Experiment 2: perennial ryegrass (Navan), perennial ryegrass (Portstewart), cocksfoot, meadow fescue, tall fescue, timothy; defined as PGS], managed under a simulated grazing regime, were incubated for 24 h with buffered rumen fluid in two separate experiments. The CH4 output per unit of feed dry-matter (DM) incubated was not affected ( P > 0·05) by PRV (range of mean values across PRV of 23·9-25·3 (SEM 0·41) mL g−1 DM) or by PGS (25·6-26·6 (SEM 0·37) mL g−1 DM). The CH4 output per unit feed DM disappearing during the in vitro rumen incubation was not affected by PRV (33·9-35·1 (SEM 0·70) mL g−1 DM), and although there was an overall PGS effect ( P < 0·05; 37·2-40·3 (SEM 0·71) mL g−1 DM), none of the paired contrasts between PGS were significant when analysed using Tukey adjusted comparisons. This outcome reflected either small-scale or a lack of treatment effects on individual herbage chemical composition (e.g. 454-483 g NDF kg−1 DM, 215-224 g CP kg−1 DM and 94-122 g water-soluble carbohydrate (WSC) kg−1 DM across PRV; 452-506 g NDF kg−1 DM, 208-243 g CP kg−1 DM and 73-131 g WSC kg−1 DM across PGS) and in vitro rumen fermentation variables. Hence, these results provide no encouragement that choices among the grasses examined, produced within the management regimes operated, would reduce enteric CH4 output per unit of feed in vivo. However, the technique utilized did not take account of animal × PRV or PGS interactions, such as potential differences in intake between animals, that may occur under farm conditions. [ABSTRACT FROM AUTHOR]

ABSTRACT Twenty-three lactic acid bacteria (LAB) isolated from three cultivars (Akiaoba, Nagahahikari and Tachiwase) of Italian ryegrass ( Lolium multiflorum Lam.) silage were precisely characterized by a combination of phenotypic tests, genotypic 16S ribosomal DNA sequencing and rapid PCR-based analyses, focusing on their useful phenotypes for silage preparation as inoculants. We successfully identified both at the species and subspecies levels: phenotypically novel Lactococcus lactis subsp. lactis, Lactobacillus brevis, Lactobacillus coryniformis subsp. torquens, Lactobacillus curvatus, Lactobacillus plantarum subsp. plantarum, Lactobacillus sakei subsp. carnosus, Leuconostoc mesenteroides subsp. dextranicum and Pediococcus parvulus. This is the first report to elucidate the presence of Lactobacillus coryniformis ssp. torquens and Leuconostoc mesenteroides subsp. dextranicum in Italian ryegrass silages. Physiological and biochemical tests revealed that phenotypic characteristics are different among the different strains of the same species and subspecies, and that the isolates show unique and diverse phenotypes related to fermentation factors, such as available carbohydrates, optimal growth pH and temperature. These results suggest that, for various well-preserved silage preparations, the isolates may be useful in producing novel inoculants corresponding to their optimally climatic and ecological niches. [ABSTRACT FROM AUTHOR]

The yield and persistency of grass species within a managed sward are a major consideration when determining species mixtures for either long-term or short-term sward management systems. Perennial ryegrass is lower yielding but more persistent than Italian ryegrass. Hybrid ryegrass, an interspecies cross between perennial and Italian ryegrass, may be higher yielding than perennial ryegrass and more persistent than Italian ryegrass. Therefore, the yield and persistency of hybrid ryegrass was investigated in Northern Ireland in five experiments, each harvested over five consecutive years, and compared with that of Italian ryegrass, perennial ryegrass and timothy. The performance of the five grass species were in the expected order; Italian ryegrass was higher yielding than hybrid ryegrass, which was higher than perennial ryegrass, with timothy the lowest, whereas perennial ryegrass and timothy had significantly higher sward densities than the hybrid and Italian ryegrasses. In addition, it was found that the rate of decline in yield and sward density with age was the same for all species. Consequently, this study indicated that the higher yielding Italian and hybrid ryegrasses could continue to out-perform perennial ryegrass for 5 years, opening the possibility of more extensive farming use of these species, particularly in Northern Ireland. [ABSTRACT FROM AUTHOR]

A diallel crossing programme amongst four contrasting white clover varieties was used to generate material for studying the interrelationships amongst those characters which affect the productivity of white clover-perennial ryegrass mixtures under a cutting-only management regime. Such a regime favoured clover growth. All the clover characters exhibited strong positive correlations with mixture yield. However, this combination of clover characters did nor promote growth of the grass companion. For this a low growing variety with a dense stolon network appeared preferable. Path analysis indicated that differences existed between the two companion grass varieties used for this experiment in their effects upon clover characters. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) belongs to the common cultivated grass species in Central and Western Europe. Despite being considered to be susceptible to drought, it is frequently used for forming the turf in urban green areas. In such areas, the water deficit in soil is recognized as one of the most important environmental factors, which can limit plant growth. The basic aim of this work was to explore the mechanisms standing behind the changes in the photosynthetic apparatus performance of two perennial ryegrass turf varieties grown under drought stress using comprehensive in vivo chlorophyll fluorescence signal analyses and plant gas exchange measurements. Drought was applied after eight weeks of sowing by controlling the humidity of the roots ground medium at the levels of 30, 50, and 70% of the field water capacity. Measurements were carried out at four times: 0, 120, and 240 h after drought application and after recovery (refilling water to 70%). We found that the difference between the two tested varieties' response resulted from a particular re-reduction of P700+ (reaction certer of PSI) that was caused by slower electron donation from P680. The difference in the rate of electron flow from Photosystem II (PSII) to PSI was also detected. The application of the combined tools (plants' photosynthetic efficiency analysis and plant gas exchange measurements) allowed exploring and explaining the specific variety response to drought stress. [ABSTRACT FROM AUTHOR]

Provides information on the Manhattan 3 perennial ryegrass, released by Pure Seed Testing in 1995. Plant description; Development of the Manhattan 3 for turf uses and recommendation for lawns and sports turfs in temperate regions.

Provides information on the Catalina perennial ryegrass, released by the Pure Seed Testing Inc. in 1995. Plant description; Recommendation for winter overseeding of bermudagrass turfs; Uses of catalina.