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This study was conducted to investigate the combined effects of elevated CO levels and cadmium (Cd) on the root morphological traits and Cd accumulation in Lolium multiflorum Lam. and Lolium perenne L. exposed to two CO levels (360 and 1 000 μl/L) and three Cd levels (0, 4, and 16 mg/L) under hydroponic conditions. The results show that elevated levels of CO increased shoot biomass more, compared to root biomass, but decreased Cd concentrations in all plant tissues. Cd exposure caused toxicity to both Lolium species, as shown by the restrictions of the root morphological parameters including root length, surface area, volume, and tip numbers. These parameters were significantly higher under elevated levels of CO than under ambient CO, especially for the number of fine roots. The increases in magnitudes of those parameters triggered by elevated levels of CO under Cd stress were more than those under non-Cd stress, suggesting an ameliorated Cd stress under elevated levels of CO. The total Cd uptake per pot, calculated on the basis of biomass, was significantly greater under elevated levels of CO than under ambient CO. Ameliorated Cd toxicity, decreased Cd concentration, and altered root morphological traits in both Lolium species under elevated levels of CO may have implications in food safety and phytoremediation. [ABSTRACT FROM AUTHOR]

Variability and future alterations in regional and global climate patterns may exert a strong control on the carbon dioxide (CO) exchange of grassland ecosystems. We used 6 years of eddy-covariance measurements to evaluate the impacts of seasonal and inter-annual variations in environmental conditions on the net ecosystem CO exchange (NEE), gross ecosystem production (GEP), and ecosystem respiration (ER) of an intensively managed grassland in the humid temperate climate of southern Ireland. In all the years of the study period, considerable uptake of atmospheric CO occurred in this grassland with a narrow range in the annual NEE from −245 to −284 g C m y, with the exception of 2008 in which the NEE reached −352 g C m y. None of the measured environmental variables (air temperature (Ta), soil moisture, photosynthetically active radiation, vapor pressure deficit (VPD), precipitation (PPT), and so on) correlated with NEE on a seasonal or annual scale because of the equal responses from the component fluxes GEP and ER to variances in these variables. Pronounced reduction of summer PPT in two out of the six studied years correlated with decreases in both GEP and ER, but not with NEE. Thus, the stable annual NEE was primarily achieved through a strong coupling of ER and GEP on seasonal and annual scales. Limited inter-annual variations in Ta (±0.5°C) and generally sufficient soil moisture availability may have further favored a stable annual NEE. Monthly ecosystem carbon use efficiency (CUE; as the ratio of NEE:GEP) during the main growing season (April 1-September 30) was negatively correlated with temperature and VPD, but positively correlated with soil moisture, whereas the annual CUE correlated negatively with annual NEE. Thus, although drier and warmer summers may mildly reduce the uptake potential, the annual uptake of atmospheric CO, in this intensively managed grassland, may be expected to continue even under predicted future climatic changes in the humid temperate climate region. [ABSTRACT FROM AUTHOR]

Ice recrystallization inhibition (IRI) proteins are thought to play an important role in conferring freezing tolerance in plants. Two genes encoding IRI proteins, LpIRI- a and LpIRI- b, were isolated from a relatively cold-tolerant perennial ryegrass cv. Caddyshack. Amino acid alignments among the IRI proteins revealed the presence of conserved repetitive IRI-domain motifs (NxVxxG/NxVxG) in both proteins. Quantitative reverse transcriptase PCR (qRT-PCR) analysis indicated that LpIRI- a was up-regulated approximately 40-fold while LpIRI- b was up-regulated sevenfold after just 1 h of cold acclimation, and by 7 days of cold acclimation the transcripts had increased 8,000-fold for LpIRI- a and 1,000-fold for LpIRI- b. Overexpression of either LpIRI- a or LpIRI- b gene in Arabidopsis increased survival rates of the seedlings following a freezing test under both cold-acclimated and nonacclimated conditions. For example, without cold acclimation a −4°C treatment reduced the wild type’s survival rate to an average of 73%, but resulted in survival rates of 85–100% for four transgenic lines. With cold acclimation, a −12°C treatment reduced the wild type’s survival rate to an average of 38.7%, while it resulted in a survival rate of 51–78.5% for transgenic lines. After cold acclimation, transgenic Arabidopsis plants overexpressing either LpIRI- a or LpIRI- b gene exhibited a consistent reduction in freezing-induced ion leakage at −8, −9, and −10°C. Furthermore, the induced expression of the LpIRI-a and LpIRI-b proteins in transgenic E. coli enhanced the freezing tolerance in host cells. Our results suggest that IRI proteins play an important role in freezing tolerance in plants. [ABSTRACT FROM AUTHOR]

In order to test the possibility for recycling use of aged refuse as sward soil, the study determined the responses of Lolium perenne L. (perennial ryegrass), Festuca arundinacea (tall fescue), and Poa annua (annual bluegrass) to its leaching. The growth of three seedlings was significantly inhibited after treatment, especially for longer treatment duration and higher concentration leaching; however, with the better growth and chlorophyll content for shorter time and lower concentration, tall fescue was more tolerant to the stress. Afterwards, several physiological responses of tall fescue were determined. For shorter treatment duration, antioxidant enzyme activities remained unchanged, and no obvious oxidative damage was observed. Prolonging exposure time, lipid peroxidation and protein oxidation occurred after treatment of higher concentration leaching, accompanying by changes of antioxidant status. It implicates that it is possible for using aged refuse as sward soil, and the critical point focused on selecting tolerant grass and controlling exposure condition. [Copyright &y& Elsevier]

The supply of nutrients to plants from organic growing media depends on mineralization as the addition of inorganic nutrients is forbidden in certified organic systems. The objective of this study was to determine the relationship between total phosphorus (P), extractable (Olsen's) P, organic P, and biomass P in growing media and uptake of P by ryegrass. Three proprietary products were used alone and combined in 1:2 and 2:1 proportions to give nine growing media. Perennial ryegrass (Lolium perenne L. cv. 'Choice') was irrigated with a modified Hoagland's solution minus P, and the shoots were harvested after 28, 56, and 84 days. There was no significant correlation between the amounts of the different forms of P in the growing media and ryegrass dry weight or P concentration in harvested grass. However, total ryegrass P uptake was significantly positively correlated with initial total P and organic P in the growing media. [ABSTRACT FROM AUTHOR]

Perennial ryegrass (Lolium perenne L.) is a widely used cool-season turfgrass species. The exact ploidy levels of the worldwide perennial ryegrass accessions in the USDA National Plant Germplasm System (NPGS) are unknown, which could complicate future use and breeding efforts. The objective of this study was to determine the ploidy level and DNA content of the 194 USDA NPGS perennial ryegrass accessions and six commercial cultivars (Brightstar SLT, Catalina II, Divine, Inspire, Manhattan 4, Silver Dollar) using flow cytometry. Among the 200 accessions, 194 diploids and six tetraploids were identified. Three tetraploids originated from Canada with the remaining from Ireland, Japan, and The Netherlands. The average DNA content was 5.60 pg/2C for diploid and 11.45 pg/2C for the tetraploid. The 2C DNA content was positively correlated (r = 0.23, P < 0.01) with seedling plant height but not seedling leaf width. This ploidy data provide important information for future marker trait analysis and cultivar improvement. [ABSTRACT FROM AUTHOR]

The aim of the present study was to investigate the relationship between Lolium perenne L. uptake of Cd, Cu, Pb, and Zn in sludge amended soils and soil availability of these elements assessed by soil sequential extraction. A greenhouse experiment was set with three representative soils of the Pampas Region, Argentina, amended with sewage sludge and sewage sludge enriched with its own incinerated ash. After the stabilization period of 60 days, half of the pots were sampled for soil analysis; the rest of the pots were sown with L. perenne and harvested 8, 12, 16 and 20 weeks after sowing, by cutting just above the soil surface. Cadmium and Pb concentrations in aerial tissues of L. perenne were below detection limits, in good agreement with the soil fractionation study. Copper and Zn concentration in the first harvest were significantly higher in the coarse textured soil compared to the fine textured soil, in contrast with soil chemical speciation. In the third harvest, there was a positive correlation between Cu and Zn concentration in aerial biomass and soil fractions usually considered of low availability. We conclude that the most available fractions obtained by soil sequential extraction did not provide the best indicator of Cu and Zn availability to L. perenne. [Copyright &y& Elsevier]

Abstract: Forage grass seed yields are often low and variable with only 10–20% of the above ground matter harvested as seed. Seed yield is affected by the amount of carbohydrate transported to the seed. However, information regarding the storage and mobilisation of carbohydrates during reproductive development in forage grasses is limited and the contribution of stored and current assimilate to seed yield from vegetative tissues is equivocal. To identify whether the total amount of carbohydrate in the plant might be limiting seed yield, and the contribution of vegetative and reproductive tissues to seed yield, the pattern of accumulation of water-soluble carbohydrates (WSC) and their remobilisation was investigated in field-grown perennial ryegrass (Lolium perenne L.) plants. Tillers were sampled from early head emergence through to harvest. Amounts of WSC in leaf blades, leaf sheaths, internodes and reproductive heads of the tillers were measured in two ways. Firstly, WSC were estimated indirectly by changes in tissue dry weight. These changes were then used to determine any apparent translocation of WSC from vegetative tissues to the developing seed. Secondly, WSC concentration was measured directly. Low molecular weight (LMW) and high molecular-weight (HMW) WSC were extracted from vegetative and reproductive tissues and the concentrations quantified using a colorimetric anthrone assay. The seed yield of the crop was high (2950kgh−1) and the dry weights and the amount of LMW and HMW WSC in vegetative and reproductive tissues changed significantly during reproductive development. High concentrations of HMW WSC were found in the internodes post head emergence and these concentrations continued to increase during seed fill through to harvest. Total dry weight of the internodes also increased over the same period. In contrast, in the leaf blades and leaf sheaths, total dry weight decreased only slightly while the initial low concentrations of WSC steadily declined. In the heads, WSC increased significantly during seed fill and subsequently declined while the dry weight continued to increase through to harvest. The ratio of LMW and HMW WSC also changed during development depending on the tissue type and growth stage. The present study indicates that the seed head itself maybe an important factor driving seed fill. Knowledge of the mechanisms that underlie carbohydrate partitioning to the seed could in future result in significantly higher yields. [Copyright &y& Elsevier]

Copyright of Journal of Environmental Engineering & Landscape Management is the property of Vilnius Gediminas Technical University and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Accurate, rapid, and nondestructive estimates of turfgrass leaf water status are important for site-specific irrigation and drought stress management. The objective of this study was to identify changes and correlations among the canopy reflectance, canopy temperature, and leaf relative water content (RWC) of perennial ryegrass (Lolium perenne L.) under water deficit conditions. Six cultivars of perennial ryegrass were subjected to dry-downs in the field from May to Aug. 2007 and from June to Aug. 2008. Turf quality was positively correlated with soil moisture (SM), RWC, and normalized difference vegetation index (NDVI), but negatively correlated with canopy and ambient temperature differentials (ΔT). ΔT was well correlated with RWC (r = -0.77 to -0.78) and SM (r = -0.66 to -0.74), whereas SM was correlated with RWC (r = 0.64 to 0.74) across seasons in both years. When a wide range of stress symptoms occurred in July and Aug., RWCs became highly correlated with AT (r = -0.80 to -0.89) and NDVI (r = 0.77 to 0.81), whereas AT was correlated with NDVI (r =-0.70 to -0.80) in both years. SM was well correlated with RWC (r = 0.71 to 0.80), NDVI (r = 0.70 to 0.73), and AT (r = -0.76 to -0.78) in July and August in both years. These results suggest that changes in AT can be used to predict well the leaf water and soil moisture content of perennial ryegrass under water deficit conditions. Combined with NDVI, the correlations can be used for direct mapping of the variability in grass water status, thus improving irrigation management. [ABSTRACT FROM AUTHOR]

Abstract: Plant lipids are complex, polar and highly unsaturated constituents of membranes. During collection and/or handling of a plant sample, the membrane integrity gets lost due to plant injury and losses of fatty acids (FA) can occur as a result of oxidative or enzymatic processes. Quantitative and qualitative effects of various post-harvest treatments on the concentrations and proportions of FA in herbage are not well known. In this study, effects of various post-harvest treatments regarding conditions following sample collection of perennial ryegrass were examined. The handling of the samples, before applying all pre-treatments, was uniform, i.e., all samples were put in a cooling box at 4°C and transported to the lab for approximately 30min. The moment when the samples arrived to the lab was considered “time zero”, and the applications of treatments started. We studied effects of two ways of sample handling (dry ice vs. no dry ice), two frozen storage temperatures (−80°C vs. −18°C) and two durations of frozen storage (1 day vs. 2 weeks) on concentrations and proportions of FA in cut herbage. The effects of the treatments appeared to be small and inconsistent, with exception of prolonged storage, which decreased FA concentrations, and increased the proportion of α-linolenic acid (C18:3). Contrary to expectation, using dry ice (rapid freezing) did not differ from slow freezing (without dry ice). Also, there were no effects of storage temperature (−80 or −18°C). Future research questions are discussed. [Copyright &y& Elsevier]

Biosolids (B) may contain various types of environmental pollutants, which can exert phytotoxic effects in plants. The effect of aqueous extracts on seed germination and the primary root growth of discaria (Discaria americana) obtained from different soil application rates of B and a mixture of B and incinerated B were investigated. The objective was to evaluate the potential use of discaria for the stabilization of B-amended soils. Ryegrass (Lolium perenne L.) was used for comparison. Compared to ryegrass, relative seed germination (RSG) was significantly lower for discaria. RSG of discaria and rye grass was inversely correlated to the electrical conductivity of extracts, although a significant adverse effect was only observed for ryegrass with the highest dose of the mixture of B and incinerated B. This dose also produced a reduction in the germination index of discaria, which could not be correlated with the parameters studied. The B extracts did not exert any significant adverse effect on the relative root growth of both species. An increase in relative root growth and germination index was observed for discaria with a field application rate equivalent of 156 t DW ha-1 of B, suggesting a stimulating effect of the amendment. The results obtained in this study suggest that germinated seedlings of discaria might be used for the stabilization of B-amended soils. However, further greenhouse and field experiments should be performed to confirm these findings. [ABSTRACT FROM AUTHOR]

Increased fuel loads due to invasive species and ecosystem changes have resulted in greater incidence, frequency and extent of wildfires over time in the Great Basin region of the U.S. There have been significant environmental and economic impacts both in terms of fire suppression costs and damage to the ecosystem and its productivity. Alternative land management, institutional changes and policies have been proposed by sixteen experienced scientists. The Great Basin Environmental Program (GBEP), a new coordinated approach involving federal and state agencies, universities and non-governmental organizations, is being established for improving the ecosystem of the region. [ABSTRACT FROM AUTHOR]

A field experiment with nine different turfgrass mixtures comprising 2,135; 4,270; 8,540 viable seeds per m² of Lolium perenne L. in combination with 8,430; 16,860; 33, 720 viable seeds per m² of Poa pratensis L. was established in Vìtrov (620 m a.s.l) in Czech republic in 2004 to evaluate their shoot density during two vegetation years. The number of L. perenne tillers increased with a higher total seeding rate and a higher proportion in the seed mixture. The shoot density of P. pratensis was in negative correlation with the number of L. perenne tillers, especially with higher total seeding rates of the mixture. [ABSTRACT FROM AUTHOR]

The seeds of three grass species non-coated or coated by the polymer Extender® were sown in Prague in 2004 and 2005 in three dates (December, February-March, April). The aim was to compare the effect of dormant or frost seeding and the seed coating on the plant surviving and development. The plants were significantly higher in average by 15.5-278% from December time of sowing by 18-257% from February/March in comparison with the swards sown in April. Number of leaves was higher by 93-528% and by 7-655%; number of tillers was higher by 13-284% and by 21-392% from December and from February/March time of sowing respectively. The effect of seed coating by Extender® was not statistically proved in this experiment. [ABSTRACT FROM AUTHOR]

Copyright of Ekologija is the property of Lithuanian Academy of Sciences Publishers and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Contamination by chromium (Cr) is widespread in agricultural soils and industrial sites. This heavy metal represents a risk to human health. In order to gain fundamental insights into the nature of the adaptation to Cr excess, the characterisation of physiological indices, including responses of photosynthetic gas exchange and chlorophyll a fluorescence along with changes in mineral nutrient contents and water status were studied in ray grass (Lolium perenne L.). Increased concentrations of Cr(VI) (0–500μM Cr) in the Coïc and Lessaint nutrient solution were applied. The growth of Lolium perenne is decreased by chromium and the leaves have lost their pigments. Chromium accumulation was greater in roots than in leaves and reached 2450 and 210μgg−1 DW, respectively with 500μM Cr(VI) in nutrient medium. The physiological parameters were severely reduced by this heavy metal. Cr induced toxicity arising from 100μM Cr(VI) and resulted in a modification of mineral content in roots and leaves, especially for Ca, Mg and Fe. The chromium stress decreased CO2 assimilation rates mainly due to stomatal closure, which reduced water loss by transpiration without decreasing the cellular available CO2. The fluorescence parameters associated with photosystem II (PSII) activity and the photochemical activity are modified by chromium. Non-radiative energy dissipation mechanisms were triggered during stress since non-photochemical quenching was increased and efficiency of excitation capture by open centers was reduced. [Copyright &y& Elsevier]

Winter hardiness is a quantitative trait and the lack of it limits geographic distribution of ryegrass. Improving winter hardiness is an important breeding goal in ryegrass breeding programs. An understanding of the genetic basis for the component traits of winter hardiness would allow more efficient selection. A three-generation interspecific population of an annual × perennial ryegrass consisting of 152 progenies was used to map quantitative trait loci (QTL) that control winter hardiness-related traits including fall growth (FG), freezing tolerance (FT), and winter survival (WS) over 2 years. A total of 39 QTL were identified for the three traits from both the female parental (MFA) and the male parental (MFB) maps, of which 13 were for FG, 6 for FT, and 20 for WS. The proportion of phenotypic variation explained by individual QTL ranged from 10.4 to 22.1%. Both FG and FT were positively correlated with WS. Common QTL were detected between FG, FT, and WS. The QTL associated with WS on linkage groups (LGs) 4 and 5, and the QTL for FT on LG 5 were consistently identified over years and maps. These consistent QTL might serve as potential tools for marker-assisted selection to improve ryegrass winter hardiness. [ABSTRACT FROM AUTHOR]

Annual ( Lolium multiflorum Lam.) and perennial ( Lolium perenne L.) ryegrasses are two important forage and turfgrass species. Improving the digestibility of forage by decreasing fiber content is a major goal in forage crop breeding programs. An annual × perennial ryegrass interspecific hybrid population was used to map quantitative trait loci (QTLs) for fiber components, neutral detergent fiber (NDF), acid detergent fiber (ADF), and acid detergent lignin (ADL), and crude protein (CP). Samples were harvested three times in August and September 2003 and August 2004, respectively. Simple interval mapping was used to detect QTLs from both the male and female parental maps previously developed for the population. Fiber components were all correlated positively with each other and were negatively correlated with CP. The largest correlations were between NDF and ADF with r = 0.86, 0.72, and 0.82 for each of the three harvests. All four traits showed intermediate broad-sense heritability values ranging from 0.35 to 0.72. A total of 63 QTLs were detected for the four traits measured over the three harvests from both the female and male maps. Coincident QTLs were detected on linkage groups (LGs) 2, 6, and 7 for NDF, LGs 1, 2, and 7 for ADF, LGs 6 and 7 for ADL, and LG 2 for CP, respectively. Coincident QTLs were also detected on LGs 2, 6, and 7 for NDF and ADF, providing evidence of the genetic basis of the observed high level of phenotypic correlation. The QTLs on LGs 2, 6, and possibly 7 for fiber components were co-located on the same LG as several lignin biosynthetic genes from perennial ryegrass. [ABSTRACT FROM AUTHOR]

The dehydration- responsive element binding proteins (DREB1)/ C-repeat (CRT) binding factors (CBF) function as transcription factors and bind to the DRE/CRT cis-acting element (core motif: G/ACCGAC) commonly present in cold-regulated ( COR) genes and subsequently upregulate the expression of such genes in Arabidopsis. We identified a DREB1A/CBF3-like gene, designated LpCBF3, from perennial ryegrass ( Lolium perenne L.) by using RT-PCR and RACE (rapid amplification of cDNA end). The LpCBF3 gene contains all the conserved domains known to exist in other CBF genes. A comprehensive phylogenetic analysis using known and computationally identified CBF homologs in this study revealed that all monocot CBF genes are separately clustered from eudicot CBF genes and the LpCBF3 is the ortholog of rice OsDREB1A/CBF3 gene. Similar to other DREB1A/CBF3 homologs, expression of the LpCBF3 is induced by cold stress, but not by abscisic acid (ABA), drought, or salinity. Overexpression of the LpCBF3 cDNA in Arabidopsis induced expression of the Arabidopsis DREB1A/CBF3 target COR genes, COR15a and RD29A, without cold acclimation. Ion leakage in leaves of the overexpression transgenic plants was significantly reduced, an indication of enhanced freezing tolerance. Our data demonstrated that LpCBF3 not only resembles DREB/CBF genes of Arabidopsis, but is also capable of functioning as a transcriptional regulator in Arabidopsis, a species distant to the grass family. [ABSTRACT FROM AUTHOR]

Determining haplotype‐specific DNA sequence information is very important in a wide range of research fields. However, no simple and robust approaches are currently available for determining haplotype‐specific sequence information. We have addressed this problem by developing a very simple and robust haplotype‐specific sequencing approach. We utilise the fact that DNA sequencing polymerases are sensitive to 3′end mismatches in the sequencing primer. By using two sequencing primers with 3′end corresponding to the two alleles in a given SNP locus, we are able to obtain allele‐specific DNA sequences from both alleles. We evaluated this direct haplotype‐specific approach by determining haplotypes within the intron 2 sequence of the fructan‐6‐fructosyltransferase ( 6 ‐ ft ) gene in Lolium perenne L . We obtained reliable haplotype‐specific sequences for all primers and genotypes evaluated. We conclude that the haplotype‐specific sequencing is robust, and that the approach has a potentially very wide application range for any diploid organism. [ABSTRACT FROM AUTHOR]

This study tested whether leaf elongation rate ( LER, mm h−1) and its components – average relative elemental growth rate ( REGRavg, mm mm−1 h−1) and leaf growth zone length ( LLGZ, mm) – are related to phosphorus (P) concentration in the growth zone ( PLGZ, mg P g−1 tissue water) of Lolium perenne L. cv. Condesa and whether such relationships are modified by the arbuscular mycorrhizal fungus (AMF) Glomus hoi. Mycorrhizal and non-mycorrhizal plants were grown at a range of P supply rates and analysed at either the same plant age or the same tiller size (defined by the length of the sheath of the youngest fully expanded leaf). Both improved P supply (up to 95%) and AMF (up to 21%) strongly increased LER. In tillers of even-aged plants, this was due to increased REGRavg and LLGZ. In even-sized tillers, it was exclusively due to increased REGRavg. REGRavg was strictly related to PLGZ ( r2 = 0.95) and independent of tiller size. Conversely, LLGZ strictly depended on tiller size ( r2 = 0.88) and not on PLGZ. Hence, P status affected leaf growth directly only through effects on relative tissue expansion rates. Symbiosis with AMF did not modify these relationships. Thus, no evidence for P status-independent effects of AMF on LER was found. [ABSTRACT FROM AUTHOR]

Perennial ryegrass ( Lolium perenne L.) is the most important grass species for temperate grassland agriculture. The level and distribution of genetic variation in gene bank ecotype collections is still largely unknown but of great interest for the planning of breeding programs. The objectives of this study were to (i) assess the molecular diversity of Polish ecotypes of perennial ryegrass, and (ii) compare the relationship between this group and German ecotypes and European cultivars investigated previously. A total number of 166 polymorphic marker bands were detected among the 171 individual plants of the 9 Polish ecotypes. In a joint analysis with 9 Polish and 22 German ecotypes, and 22 European cultivars 172 polymorphic RAPD markers could be found. Genetic distance among the Polish ecotypes ranged from 0.31 to 0.51, while for all 53 populations a broader range was detected (0.25–0.67). An analysis of molecular variance (AMOVA) revealed a much larger variation within populations (71%) than among them (29%). The Polish ecotypes contained the highest within population variation (74%). The largest among group difference (15%) was found between the Polish ecotypes versus all other accessions. We conclude that the Polish ecotypes represent a valuable genetic resource for enlarging the genetic variation in the West European germplasm pool of perennial ryegrass. [ABSTRACT FROM AUTHOR]

Previous research has demonstrated that bispyribac-sodium can selectively control established annual bluegrass (Poa annua L.) in creeping bentgrass (Agrostis stolonifera L.). Annual bluegrass is also a problematic weed in other cool-season turfgrass species. However, the relative tolerance of other cool-season turfgrass species to bispyribac is not known. Field experiments were conducted at Adelphia, N.J., in 2002 and 2003 to gain understanding of the phytotoxic effects that bispyribac may have on kentucky bluegrass (Poa pratensis L.), perennial ryegrass (Lolium perenne L.), tall fescue (Festuca arundinacea (L.) Schreb.), and chewings fine fescue (Festuca rubra L. subsp, commutata Gaud.). Single applications of bispyribac at 37 to 296 g ·ha-1 were applied to mature stands of each species on 11 June, 2002 and 10 June, 2003. Visual injury was evaluated and clippings were collected 35 and 70 days after treatment (DAT). Visual injury at 35 DAT increased as bispyribac rate increased. Kentucky bluegrass was least tolerant to bispyribac with up to 28% injury when applied at 296 g ·ha-1. Injury on other species did not exceed 20%. Initial injury on perennial ryegrass, tall fescue, and chewings fine fescue was primarily in the form of chiorosis, while kentucky bluegrass exhibited more severe stunting and thinning symptoms. Bispyribac at rates from 74 to 296 g ·ha-1 reduced kentucky bluegrass clipping weights by 19% to 35%, respectively, as compared to the untreated control at 35 DAT in 2002. Initial visual injury on perennial ryegrass, tall fescue, and chewings fine fescue dissipated to ≤5% by 70 DAT. However, recovery of kentucky bluegrass was less complete. These studies suggest that bispyribac-sodium has potential to severely injure kentucky bluegrass. Injury on perennial ryegrass, tall fescue, and chewings fine fescue appears to be less severe and persistent; therefore, bispyribac can be used for weed control in these species. Chemical names used: 2,6-bis[(4,6-dimethoxy-2-pyrimidinyl)oxy]benzoic acid (bispyribac-sodium). [ABSTRACT FROM AUTHOR]

The CO2 respired by leaves is13C-enriched relative to leaf biomass and putative respiratory substrates (Ghashghaieet al.,Phytochemistry Reviews2, 145–161, 2003), but how this relates to the13C content of root, or whole plant respiratory CO2 is unknown. The C isotope composition of respiratory CO2 (δR) from shoots and roots of sunflower (Helianthus annuusL.), alfalfa (Medicago sativaL.), and perennial ryegrass (Lolium perenneL.) growing in a range of conditions was analysed. In all instances plants were grown in controlled environments with CO2 of constant concentration andδ13C. Respiration of roots and shoots of individual plants was measured with an open CO2 exchange system interfaced with a mass spectrometer. Respiratory CO2 from shoots was always13C-enriched relative to that of roots. Conversely, shoot biomass was always13C-depleted relative to root biomass. Theδ-difference between shoot and root respiratory CO2 was variable, and negatively correlated with theδ-difference between shoot and root biomass (r2 = 0.52,P = 0.023), suggesting isotope effects during biosynthesis.13C discrimination in respiration (R) of shoots, roots and whole plants (eShoot,eRoot,ePlant) was assessed ase = (δSubstrate − δR)/(1 + δR/1000), where root and shoot substrate is defined as imported C, and plant substrate is total photosynthate. Estimates were obtained from C isotope balances of shoots, roots and whole plants of sunflower and alfalfa using growth and respiration data collected at intervals of 1 to 2 weeks.eplant andeShoot differed significantly from zero.eplant ranged between−0.4 and−0.9‰, whereaseShoot was much greater (−0.6 to−1.9‰).eRoot was not significantly different from zero. The present results help to resolve the apparent conflict between leaf- and ecosystem-level13C discrimination in respiration. [ABSTRACT FROM AUTHOR]

Abstract: Perennial ryegrass (Lolium perenne L.) was grown for seed in field trials in order to investigate the temporal variation in plant nitrogen (N) concentration during ontogeny. Crops were sown in three successive years and grown with five N fertiliser rates applied in the autumn and in the spring (autumn–spring): 0–0, 0–50, 0–100, 30–120 or 60–140kg Nha-1. Within each N fertiliser rate, N concentration in the plants increased from the initiation of spring growth and reached a maximum of 4.8% at 450–500 growing degree-days (GDD) after which it decreased to 0.8% at 1150–1200 GDD. This pattern of plant N concentration was consistently low at each N fertiliser rate and between years whereas the variation in plant N concentration within each year was high as a result of the different N fertiliser rates. Nitrogen fertiliser rate up to 150kg Nha-1 increased the seed yields. During spring growth 89% of the variation in plant N concentration could be explained by a non-linear function of GDD. Maximum variation occurred at 480 GDD, with a 95% confidence interval between 428 GDD and 540 GDD. Plant N concentrations measured at 424 GDD in 1998, 447 GDD in 1997, and 497 GDD in 1996, and the resulting correlation coefficients (r2) between N concentration and seed yield were 0.81, 0.71 and 0.92, respectively. It is concluded that the variation in plant N concentration during ontogeny in perennial ryegrass is related to different N fertiliser rates and that the greatest variation in plant N concentration was in the period from 428 GDD to 540 GDD. [Copyright &y& Elsevier]

Silvopastoral systems comprise part of the continued expansion of conifer plantings on grassland in New Zealand. Greater understanding of the short term dynamics of soil organic P in such systems will further our knowledge about soil carbon and phosphorus relationships which will enable improved nutrient management in the field. A glasshouse experiment was carried out to examine the short-term effects (36 weeks) of combinations of radiata pine (Pinus radiata), lucerne (Medicago sativaL.) and perennial ryegrass (Lolium perenneL.) grown in the same soil type with a range of carbon (C) and phosphorus (P) levels on plant P uptake and the specific mineralisation rate (SMR). The SMR is defined as net mineralisation rate (i.e. gross mineralisation less microbial and geochemical uptake) and calculated from organic P decline as a percentage of organic P in the original soil before planting. This included an investigation of the effect of tree ectomycorrhizal (EM) hyphae on soil organic P. Plant P uptake was positively correlated with water soluble organic carbon (WSOC) and SMR, which in turn was closely related to soil C levels. The soils with high WSOC and C levels (which also contained high levels of labile inorganic and organic P) enabled high P uptake. Although P uptake was the greatest under radiata pine, the trees tended to deplete inorganic P to a lesser extent than the forages. When tree and forage species were combined, P uptake by forages was similar to when the forages were grown alone. The various soil and plant treatments significantly affected SMR. The two low C soils, showed the greatest organic P mineralisation while a high C soil, which contained significant levels of bicarbonate extracted inorganic P at planting and was under a long established undisturbed pasture, showed the least mineralisation. Trees grown alone showed the greatest SMR, EM hyphae and trees with lucerne were slightly lower than trees alone, while the forages showed the lowest SMR. The findings of this study showed that changes in organic P are strongly influenced by interactions between plant species (radiata pine, lucerne, ryegrass) and soil properties as determined by land use and management. [ABSTRACT FROM AUTHOR]

Three sludge types from the same treatment stream (undigested liquid, anaerobically digested liquid and dewatered, anaerobically digested cake) were used in a field based tub study. Amendments (4, 8, and 16 Mg dry solid (ds) ha−1) were incorporated into the upper 15 cm of a sandy loam soil prior to sowing with rye-grass (Lolium perenne L.). Nitrogen transformations in the soil were determined for the 80 d period following incorporation. Nitrogen uptake and crop yield were measured in the cut sward 35 and 70 d after sowing. The study showed that application of sewage sludge at rates as low as 4 Mg ha−1 can have a nutritional benefit to rye-grass over the two harvests. Differences in N transformation, and hence crop nutritional benefit, between sludge types were evident throughout the experiment. In particular, the dewatering process changed the mineral N characteristics of the anaerobically digested sludge, which, when not dewatered, outperformed the other sludges in terms of yield and mineralisation rate at both harvests. The dewatered sludge produced the lowest yield of rye-grass. The undigested liquid sludge had the lowest foliar N and soil NO3–N concentrations, possibly immobilised as the large oxidisable C component of this sludge was metabolised by the microbial biomass. Correlation data support the concept of preferential uptake of NH4–N over NO3–N in Lolium perenne. Results are discussed in the context of managing sludge type and application for a plant nutrient source and NO3–N release. [Copyright &y& Elsevier]

A 13C/12C mass spectrometer was interfaced with a open gas exchange system including four growth chambers to investigate CO2 exchange components of perennial ryegrass ( Lolium perenne L.) stands. Chambers were fed with air containing CO2 with known δ13C ( δCΟ2−2.6 or −46.8‰). The system did not fractionate C isotopes and no extraneous CO2 leaked into chambers. The on-line 13C discrimination (Δ) of ryegrass stands in light was independent of δCΟ2 when δCΟ2 was constant. The δ of CO2 exchanged by the stands in light ( δNd) and darkness ( δRn) differed by 0.7‰, suggesting some Δ in dark respiration at the stand-level. However, Δ decreased by ∼ 10‰ when δCΟ2 was switched from −46.8 to −2.5‰, and increased by ∼ 10‰ following a shift from −2.6 to −46.7‰ due to isotopic disequilibria between photosynthetic and respiratory fluxes. Isotopic imbalances were used to assess (non-photorespiratory) respiration in light and the replacement of the respiratory substrate pool(s) by new photosynthate. Respiration was partially inhibited by light, but increased during the light period and decreased in darkness, in association with temperature changes. The labelling kinetics of respiratory CO2 indicated the existence of two major respiratory substrate pools: a fast pool which was exchanged within hours, and a slow pool accounting for ∼ 60% of total respiration and having a mean residence time of 3.6 d. [ABSTRACT FROM AUTHOR]

The stay‐green mutation of the nuclear gene sid results in inhibition of chlorophyll degradation during leaf senescence in grasses, reducing N remobilization from senescing leaves. Effects on growth of Lolium perenne L. were investigated during N starvation (over 18 d) and after severe defoliation, when leaf growth depends on the remobilization of internal N. Rates of dry matter production, partitioning between shoots and roots, and re‐partitioning of N from shoots to roots were very similar in stay‐green and normal plants under N starvation. Km and Vmax for net uptake of NH4+ were also similar for both genotypes, and Vmax increased with the duration of N deprivation. The mutation had little effect on recovery of leaf growth following severe defoliation, but stay‐green plants recommenced NO3– and K+ uptake 1 d later than normal plants. Import of remobilized N into new leaves was generally similar in both lines. However, stay‐green plants remobilized less N from stubble compared with normal plants. It was concluded that the sid locus stay‐green mutation has no significant adverse effect on the growth of L. perenne during N starvation, or recovery from severe defoliation when plants are grown under an optimal regime of NO3– supply both before and after defoliation. The absence of any effect on leaf dry matter production implies that the difference in foliar N availability attributable to this mutation has little bearing on productivity, at least in the short to medium term. [ABSTRACT FROM PUBLISHER]

To allow improved prediction of daily herbage intake of dairy cows in rotational grazing systems, intake behaviour was assessed throughout the day in 24-h paddocks. Herbage intake in 16 lactating Holstein–Friesian cows was assessed using the short-term (1-h) weight gain method at four predetermined natural meal times throughout the day (early morning, T1; late morning, T2; mid-afternoon, T3; and early evening, T4). The study comprised two 4-day experiments, each with a cross-over design of four blocks. In both experiments, cows grazed a 24-h paddock daily, and the effect of the immediately previous grazing experience on intake behaviour was investigated throughout the day, taking account of daily fluctuations in the short-term physiological condition of the cows. Experiment 1 was carried out to investigate overall grazing behaviour during meals as a sward is progressively depleted during the day, with intake being assessed within the paddock and, hence, on a depleted sward. Experiment 2 similarly investigated the effect of sward depletion and physiological condition throughout the day on intake, but cows were removed to fresh, undefoliated swards during intake measurement periods; thus, intake rate was not influenced by differences in sward condition. Intake behaviour from both experiments was compared to establish the effect on herbage intake of changes in sward state and non-sward factors. In Experiment 1, sward surface height, available herbage mass, proportion of leaf and green leaf mass declined as the day progressed. Bite mass declined with sward depletion, and mean intake rate was 1·64 kg dry matter (DM) h–1 , which was significantly lower at T3 (P < 0·01) than during other meals. In Experiment 2, plot sward conditions did not change throughout the day, and intake behaviour also remained constant, with a mean intake rate of 2·11 kg DM h–1 . Mean bite depth as a proportion of pregrazing extended... [ABSTRACT FROM AUTHOR]

Leaf markings are widespread in Trifolium spp. White clover (T. repens L.) material has been produced at the Institute of Grassland and Environmental Research (IGER) Aberystwyth, UK, which demonstrates the ‘filled - V’ leaf mark as a subtle but clearly identifiable mark with little seasonal variation in expression. This paper describes how a population of genotypically identical individual white clover plants (clones), created from this material, can be used in grazed swards to monitor changes in morphology at the clone and ramet level. In a pilot experiment, the effect of a late silage cut on the white clover component of grazed mixed swards was investigated. Leaf-mark plants were introduced into known positions in a grass/clover sward in 1997 and monitored during 1998 under two grazing regimes: (1) continuous grazing to a sward surface height of 4 cm (treatment G); and (2) grazing, followed by a single late-season silage cut, a brief rest period, and a return to autumn sheep grazing (treatment GRG). The GRG treatment had a significant and rapid effect, producing larger clones with a larger number of ramets and higher proportions of complex ramets than the G treatment. As ramet complexity increased the treatment effect intensified, resulting in a four-fold increase in clone size, together with an enhanced ability to spread into the sward. The GRG treatment allowed a more widespread dispersal of individual units and this is likely to enhance the opportunity for ramets to encounter favourable micro-environments for survival and growth. The benefits and limitations of the procedures are discussed. [ABSTRACT FROM AUTHOR]

The greater sensitivity of white clover (Trifolium repens L.) to low temperature compared with perennial ryegrass (Lolium perenne L.) is a major problem in sustaining the relative contributions to yield of the two species in mixed swards. The objectives of this investigation were to examine the dynamics of leaf development of two white clover cultivars, AberHerald and Grasslands Huia, under field conditions, and to determine the significance of leaf area in winter, and of competition by perennial ryegrass, for the overwintering and regrowth of white clover in spring. Undefoliated white clover plants developed 3·8–6·6 new leaves between late autumn and early spring, and stolon dry matter and total non-structural carbohydrates (TNC) content increased by 262 and by 68% respectively. In contrast, white clover plants that were defoliated frequently during the winter showed a 28% decrease in stolon dry matter and an 82% decrease in the content of TNC. Frequent defoliation in winter caused severe reduction in the rates of emergence of nodes (by 60%) and of buds (by 67%), and the rate of death of nodes and buds increased by a factor of 10, leading to small stolon systems of individual plants in spring. Competition had similar, but weaker, effects to those of winter defoliation, presumably caused by shading of white clover leaves. AberHerald had a higher cumulative leaf emergence (by 22%), a higher mean leaf number (by 23%), a higher stolon DM (by 36%) and a higher TNC content per plant (by 115%) than Grasslands Huia. Results demonstrate the crucial positive role of leaf area during winter, the negative effect of grass competition, and the importance of the clover cultivar, for the overwintering and subsequent spring regrowth of white clover. [ABSTRACT FROM AUTHOR]

Polymorphisms in electrophoretic patterns obtained by isoelectric focusing (IEF) were examined to evaluate their suitability for cultivar identification in perennial ryegrass ( Lolium perenne L.). It was possible to discriminate 64 (94%) of 68 cultivars by combining results from esterase and total protein analysis. Discrimination was based on quantitative differences (relative band intensity) rather than on qualitative differences (presence or absence of bands). Esterase patterns from different recent (fresh to seven years old) seed lots of the same perennial ryegrass cultivars were very stable. Occasionally, minor differences in band intensity were observed between recent and old (up to 30 years old) seed lots of a cultivar. Storage of meal samples up to two years at −20 °C had no effect on the total protein patterns. No correlation was found between esterase patterns and ploidy level, cultivar type (pasture or turf), heading date or breeding company. Esterase patterns appeared to be unsuitable markers for the selection of reference cultivars for distinctiveness, uniformity, and stability (DUS) testing, because no correlation was found between cultivars on the basis of esterase banding patterns and morphological characteristics. [ABSTRACT FROM AUTHOR]

Three widely used cultivars of each of the species Festuca pratensis Huds., Lolium perenne L., and Dactylis glomerata L. were investigated by means of randomly amplified polymorphic DNA (RAPD) markers and vegetative growth traits in order to investigate genetic variability within each cultivar and to compare the level of diversity among cultivars and species. RAPD markers allowed a clear separation of the three species. Genetic variability based on RAPD markers was considerably lower for F. pratensis cultivars than for L. perenne and D. glomerata cultivars which showed similar levels of variability. The proportion of variability due to variation within cultivars, determined by an analysis of molecular variance, was lower in F. pratensis (64.6%) than in L. perenne (82.4%) and D. glomerata (85.1%). A comparison of F. pratensis and L. perenne, based on vegetative growth traits, confirmed the differences in genetic variability within cultivars. F. pratensis showed lower coefficients of genetic variation for eight of ten traits when compared to L. perenne. This study demonstrates considerable differences in genetic variability which may have consequences for the adaptability and persistency of individual cultivars. [ABSTRACT FROM AUTHOR]

Stable transformation of perennial ryegrass ( Lolium perenne L.) was achieved by biolistic bombardment of a non embryogenic cell suspension culture, using the hpt and gusA gene. The transformation yielded on the average 5 callus lines per bombardment (1.4×10 cells). Stable integration of the genes into the plant genome was demonstrated by Southern analysis of DNA, isolated from hygromycin-resistant callus lines. The gusA reporter gene, which was regulated by the constitutive promoter of the rice gene GOS2, was expressed in both transient and stable transformation assays, indicating that this promoter is suitable for expression of a transferred gene in perennial ryegrass. Long-term GUS expression was observed in ca. 40% of the callus lines, whereas the other callus lines showed instability after 6 months and 1 year of culture. [ABSTRACT FROM AUTHOR]