首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 31 毫秒
1.
An assessment of genetic improvement in turf‐type perennial ryegrass was performed at a network of six locations. A comparison was made of the turf performances of five natural populations, five forage‐type cultivars used for turf seeding until the 1980s and 31 turf‐type cultivars released from 1974 to 2004. Populations and cultivars were also compared in two spaced‐plant experiments and in two seed‐yield trials. Trait regressions on registration year of turf‐type cultivars showed that breeding had been highly successful in improving the turf aesthetic merit (from +8·8 to +12·5% per decade according to seasons), wear tolerance (+5·4% per decade) and crown‐rust resistance (+8·9% per decade) and in lessening the turf height increase rate (?0·43 mm day?1 per decade). Turf winter greenness had been marginally improved, whereas summer greenness and seed yield had not been significantly changed. A multivariate analysis provided evidence that turf density and fineness played a major role in the visual assessment of turf aesthetic merit and that wear tolerance was closely associated with turf density. Conflicting trait associations may have precluded improvements in turf ground‐cover 3 months after sowing, turf winter greenness and turf persistency.  相似文献   

2.
Bird strike is a significant problem for the aviation industry, caused in part by the attractiveness of the grass surrounding airports to birds. Endophyte‐infected grasses such as Avanex® have been shown to reduce bird populations at airports through the production of secondary metabolites. These metabolites are unpalatable to herbivorous, omnivorous and granivorous birds and are known to reduce insect densities, thereby making the sown areas less attractive to insectivorous birds. Raptors also provide a bird‐strike threat which could be reduced by controlling mouse populations around airports. In this study, the effect of endophyte‐infected seed on mouse feeding behaviour has been investigated. By performing a choice trial offering diets containing endophyte‐infected and endophyte‐free tall fescue seed, it was shown that endophyte‐infected seed was less palatable to mice (P < 0·001 in a 14‐d trial). Furthermore, when diet positions were reversed, mouse feeding behaviour was modified to again select endophyte‐free material (P < 0·001 over a further 14 d). This result shows that endophyte‐infected grasses could not only be used in the control of bird populations but they also have the potential to control mouse populations which in turn would decrease the number of raptors. This use of endophyte‐infected grasses in areas surrounding airport runways shows great promise for the aviation industry.  相似文献   

3.
Perennial forage legumes may be pivotal for improving the sustainability of Mediterranean rainfed farming systems. This study summarizes the outcomes of a study aimed at characterizing morphological and agronomic traits of new germplasm of Bituminaria bituminosa and B. morisiana in Mediterranean environments. Five B. morisiana and three B. bituminosa native populations were evaluated in a small‐plot field experiment in Sardinia (Italy) and compared with seven Spanish accessions of B. bituminosa. The two Bituminaria species differed greatly in morphological traits and the beginning of the flowering stage, and remarkable variations between species were found for forage production and its seasonal distribution, seed yield and persistence. Average cumulative dry‐matter yield was higher in B. bituminosa than in B. morisiana (+7.6%; 297 vs. 276 g per plant). Average 3‐year seed production varied greatly between accessions (from 0.3 to 141 g per plant). Differences for these traits were also found between Sardinian and Spanish germplasm of B. bituminosa. Four clusters were generated by K‐means clustering. Accessions included in cluster III exhibited a positive combination of favourable forage production, high seed yield and satisfactory persistence. Nonetheless, the cluster analysis did not highlight a sharp discrimination between Bituminaria species. The overall results revealed the potential role of Sardinian accessions of B. bituminosa and B. morisiana in extending the forage season and for increased resilience of grasslands in Sardinia and other Mediterranean regions under rainfed conditions.  相似文献   

4.
In outbreeding species, such as perennial ryegrass, most plants are heterozygous for genes controlling agronomic characters and varieties must usually be based on more than one plant to avoid inbreeding depression. This leads to the possibility of change under the selective action of seed multiplication.
Several stocks of S23 perennial ryegrass were examined to see whether such a change occurred; Irish, Kent and Hunsballe were grown for comparison.
The characters recorded were date of ear emergence, winter requirement before heading, and leaf size, rate of leaf appearance, tillering and dry-weight production in the young seedling.
A slight shift towards earliness of heading occurred during seed multiplication, but no regular change in the other characters could be detected. The S23 stocks could readily be distinguished from Hunsballe and, less easily, from Irish, as early as the sixth leaf stage.
It is concluded that although considerable genetic variation for all these characters exists within the S23 stocks, changes during seed multiplication are not inevitable but depend on the management of the crop.  相似文献   

5.
Alpine bluegrass (Poa alpina L.) is common in mountain areas, where it represents a valuable forage resource and is widely used for ecological restoration of disturbed landscapes. This study assessed the variation of germplasm from the Rhaetian Alps, Italy. Both seed production and morphology were examined for potential use in restoration projects and for conservation and selection purposes of local genetic resources. The effects of the ex situ growing site were also assessed in two altitude‐contrasting sites. Individual populations harboured great phenotypic diversity for all traits, including seed yield, while variation among valleys of origin was less manifest. Noticeable site‐specific population yield responses were observed, suggesting that the environment adopted for seed production may steer the choice of materials to be multiplied. The longer vegetative period in the lowland site, combined with environment‐tailored agronomic practices, contributed to better plant growth, seed yield and survival compared to the mountain site, suggesting that seed production of this Alpine species could be feasible in a lowland environment when adequate inputs were provided. One valley (Valchiavenna) displayed high average levels of seed yield and plant vigour across growing sites, indicating its possible value as a source of germplasm suitable for resowing at high altitude.  相似文献   

6.
First‐year crops of diploid perennial ryegrass (cvs. Meridian, Bronsyn and Grasslands Impact) were sown on 1 April and 14 May 2008. Applications of trinexapac ethyl (TE) plant growth regulator at 0, 200 and 400 g a.i. ha?1 were used to shorten stems to examine the impact of seed growth. Seed filling followed a consistent sigmoidal growth pattern with a lag phase of 127°C days, and linear duration of 390°C days. Time to 95% of final seed weight was 517°C days. Seed yield increases from TE were from higher numbers of first‐grade seeds m?2, achieved by a higher rate of seed filling during the linear phase of 0·115 mg per °C day per spike. For all cultivars, the maximum stem dry weight occurred at 310–400°C days post‐anthesis, which suggest the stem was a strong sink. As seeds developed, their demand for assimilate increased and they drew more from the stem. At harvest, stem weights from TE treatments were 25% heavier than at anthesis, while untreated ‘Bronsyn’ and ‘Grasslands Impact’ stems were similar to those at anthesis. Thus, stems treated with TE contributed assimilates to increase seed yield but were still a net sink with assimilates in the stem at harvest. Trinexapac ethyl rate induced an inverse relationship between seed yield and stem height. This showed that competition for assimilate between stems and growing seeds limited the seed yield. Management or genetic factors that reduce stem height are likely to increase seed yields of perennial ryegrass.  相似文献   

7.
Three Lolium perenne L. genotypes collected from different natural habitats were tested for the effects of their fungal endophyte Neotyphodium spp. on plant growth and seed yield. Half the clones of the originally infected plants were subjected to fungicide treatment to eradicate the endophytes. In an experiment, the clones were planted separately into pots and were either watered adequately or subjected to drought stress. In the genotype collected from a dry site, the endophyte infection reduced plant growth at an adequate water supply, but increased regrowth under drought. In the genotype from a periodically either flooded or dry site, endophyte infection significantly promoted the development of reproductive tillers and seed production (effects which are associated with adaptation to drought). In contrast, the genotype that originated from a wet site showed higher sensitivity to drought stress when endophyte infection was present. The results suggest that environmental conditions in the original habitat of the plants may influence the symbiotic interaction between plant and fungus, probably through natural selection. However, endophyte‐induced increases in root dry weight and root/shoot ratio were recorded for all three genotypes. These features could be beneficial for plant persistence, especially on sites where water is the growth‐limiting factor.  相似文献   

8.
Chinese leymus [Leymus chinensis (Trin.) Tzvel.] is an important forage distributed in East Asia. The seed‐set rates and the pollen–stigma compatibility in six populations were investigated in 2001. Proportionately seed‐set ranged from 0·065 to 0·567 under open pollination and 0·0056 to 0·0426 under self‐pollination. The former is significantly higher than the latter in each population. Microscopic observations showed that proportionately only 0·0551 to 0·1167 of self‐pollinated pollen grains were compatible but most cross‐pollinated pollen grains were compatible. The tubes of most incompatible pollen grains aborted upon entering into the stigmas. Among the six populations, there was a significant correlation between seed‐set under open pollination and the compatible pollen rates under cross‐pollination. These results suggest that Chinese leymus is a self‐incompatible species, and the compatibility of pollen and stigma might be one of the factors influencing seed‐set in natural conditions. This information will be useful for future breeding efforts.  相似文献   

9.
Annual ryegrass (Lolium multiflorum Lam.) is a primary forage resource for livestock producers throughout the south‐eastern USA during the winter‐growing season. It is important for livestock producers to begin grazing annual ryegrass as early as possible and any management practices maximizing early season production could be beneficial. To assess the impact of seeding rate on subsequent yield, yield distribution, quality, seedling density, and end‐of‐season plant and tiller density, a 2‐year study was initiated at four locations in Louisiana. Three annual ryegrass cultivars, varying in seed size, were established at four seeding rates based on pure live seed (PLS) rates of 400, 800, 1200 and 1600 PLS m?2. There was no advantage in total yield from increasing seeding rates beyond 800 PLS m?2. However, first‐harvest yields increased from 360 to 930 kg dry matter (DM) ha?1 as seeding rate increased from 400 to 1600 PLS m?2. Crude protein and neutral‐detergent fibre concentrations, and in vitro DM digestibility, were not affected by seeding rate. Seedling density and end‐of‐season plant numbers increased as seeding rate increased. However, stems per plant decreased as seeding rate increased, indicating compensatory tillering for the reduced plant numbers observed at the lower seeding rates. These results indicate first‐harvest yield can be increased by planting at higher seeding rates but total yields are not increased.  相似文献   

10.
The common forage grass Lolium perenne has evolved with the systemic fungal endophyte Epichloë festucae var. lolii. The endophyte provides herbivore resistance to the grass due to defensive alkaloids, some of which are toxic to grazing livestock. In this field study, we determine whether distribution of the endophyte‐grass association changes along a land‐use intensity gradient on 87 managed grasslands in three German regions. Endophyte infections were detected in 66% of the studied sites and infection rates within infected sites ranged from 1% to 95%. Alkaloid concentrations of lolitrem B (vertebrate toxin) exceeded the toxicity thresholds in 50 (14%) of 351 infected plants and of peramine (invertebrate deterrent/toxin) in 12 (3%) of 351 plants. Infection rates and alkaloid concentrations were not significantly affected by land‐use intensity and region, but alkaloid concentrations were higher in summer compared to spring. We conclude that risks for livestock intoxication are currently low, as (i) average alkaloid concentrations per grassland were always below toxicity thresholds and as (ii) none of the grasslands was dominated by L. perenne. We suggest avoidance of grass monocultures in Europe to keep intoxication risks for livestock low; we also recommend regular examination of seeds and grasslands, as seed producers might accidentally distribute infected seeds, and as climate warming might further enhance the distribution of Epichloë endophytes in European grasslands.  相似文献   

11.
The selection by sheep (six Coopworth ewe hoggets, 44·3 ± 4·6 kg live weight) and goats (six Saanen/Anglo‐Nubian yearling males, 38·1 ± 3·8 kg live weight) for perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) and for sward height was measured in two experiments involving paired turves. Pairs of turves with herbage of differing height and of either the same or different plant species were offered. One sward (fixed height species, FHS) was always offered at 130 mm and the other (variable height species, VHS) at 130, 90 or 50 mm. Turves (450 mm × 220 mm) were cut to a soil depth of 100–150 mm from areas of perennial ryegrass and white clover regrown to the desired height after previously being cut to 30 mm. Each turf in a pair was weighed (±1 g) before and after grazing by penned animals maintained on a barley‐based pelleted diet. The number of prehending bites taken from each turf was recorded over a grazing period (128 ± 12 s). Bite mass, bite rate and intake rate were calculated. As the sward height of the VHS turf declined, an increasing proportion of the diet was selected from the 130 mm turf. When averaged over all height contrasts, both animal species selected a higher proportion (0·776 ± 0·026) of their diet from 130‐mm white clover than from 130‐mm perennial ryegrass (0·591 ± 0·018) turves. On average, goats selected a higher proportion (0·721 ± 0·022) of their dry‐matter (DM) intake from the 130‐mm turf than sheep (0·646 ± 0·019), but the effect was not consistent. In contrasts with perennial ryegrass as the VHS (and both perennial ryegrass and white clover as FHS), the proportion of the diet selected from the 130‐mm turf was very similar for both animal species. However, with white clover as the VHS (and both perennial ryegrass and white clover as FHS), goats selected a higher proportion of their intake from the 130‐mm turf to the extent that in the 130‐mm perennial ryegrass/50‐mm white clover contrast sheep showed as strong selection for 50‐mm white clover as goats did for 130‐mm perennial ryegrass. This lesser selection of goats for white clover as its height in a sward declines is likely to contribute to the higher white clover content observed in swards grazed by goats. Bite mass was greater on white clover (246 ± 5 mg DM bite–1) than on perennial ryegrass (173 ± 5 mg DM bite–1) and was greater for goats (255 ± 6 mg DM bite–1) than for sheep (195 ± 5 mg DM bite–1). Bite rate was greater on perennial ryegrass (45·9 ± 1·0 bites min–1) than on white clover (39·9 ± 1·0 bites min–1) and was greater for sheep (45·5 ± 1·1 bites min–1) than for goats (42·5 ± 1·1 bites min–1). Apparent intake rate by both sheep and goats was lower (mean, 5·0 ± 0·29 g DM min–1) on 130 mm perennial ryegrass/white clover than on 130 mm perennial ryegrass/perennial ryegrass (7·0 ± 0·27 g DM min–1), but was higher (9·62 ± 0·29 g DM min–1) on 130‐mm white clover/perennial ryegrass than on 130‐mm white clover/white clover (8·2 ± 0·29 g DM min–1) combinations.  相似文献   

12.
Festuca rubra subsp. pruinosa is a grass that inhabits the sea cliffs of the Atlantic coasts of Europe. Four populations of this plant in the northern coast of Galicia, in northern Spain, were analysed for the presence of fungal endophytes. Of the plants included in the study, on average 0·69 were infected by an intercellular fungal endophyte. Using morphological and molecular characters, this endophyte was identified as Epichloë festucae, a clavicipitaceous, seed‐transmitted species. A half‐sibling line, consisting of endophyte‐free and endophyte‐infected plants, was developed and used to test whether the presence of the fungus affected the response of the plants to salinity. Dry weights of infected or uninfected plants, watered with sea‐water solutions or tap water, did not significantly differ.  相似文献   

13.
Seed yield is of crucial importance for the marketing of lucerne varieties. Statistical records for farmers’ production of certified seed suggested a slightly higher seed‐yielding ability of Italian landraces over improved varieties (proportionately 0·052). The aims were to: (i) assess the variation among landraces, and compare the germplasm of landrace and improved varieties, for seed‐yielding ability; and (ii) investigate the relationships between seed yield, environment of origin and forage yield of the landraces. Thirteen farm landraces belonging to the seven commercial ecotypes of northern Italy and four improved varieties were evaluated for seed yield in the third cropping year and for herbage yield over twelve harvests. Landraces differed in seed yield and herbage yield (P < 0·05). Landrace material, compared with variety germplasm, showed a non‐significant trend towards higher seed yield (proportionately 0·047) and had similar herbage yield and plant density at the onset of the third cropping year. Seed yield of landraces was unrelated to forage yield and was associated with frequent mowing and earlier year of seed production on its farm of origin.  相似文献   

14.
Red clover (Trifolium pratense) grown in mixtures with grasses often constitutes a lower proportion of total yield in spring than in summer growth. A more even red clover proportion between the harvests would benefit forage quality and management at feeding. We investigated whether inclusion of early versus late‐maturing red clover varieties could reduce this disproportionality. In a two‐year field trial harvested three times per season, each of six red clover varieties was grown in two grass mixtures. Rate of phenological development did not differ during spring growth, but did so in regrowth after first and second cuts. Here, the earliest varieties constituted the highest proportion. At all harvests, the early varieties had lower crude protein concentrations and a higher content of neutral detergent fibre (NDF) and indigestible NDF than the late varieties. Clover proportion was higher in swards with a mixture of timothy and meadow fescue than in swards with perennial ryegrass during the first year and lower in the second year. It is concluded that developmental rate should be explored further as a key character for red clover competiveness in spring growth of rapidly elongating grasses.  相似文献   

15.
Abstract Annual ryegrass (Lolium multiflorum Lam.) is grown on more than one million ha in the south‐eastern USA each year. Recommended and actual seeding rates vary substantially within the region. The objective of this study was to evaluate variation in seed weight, germination, seedling vigour and seasonal yield performance among annual ryegrass cultivars. During 1997, 1998 and 1999, seed from fourteen commercial cultivars was weighed and germinated to determine numbers of pure live seed (PLS) m?2 before yield evaluation at four locations. Seed from ten cultivars was planted at 0·7 and 2·0 cm depth in a greenhouse study to evaluate relative seedling vigour. Cultivar mean single‐seed weight ranged from 2·4 to 4·8 mg in 1997, 1·8 to 4·5 mg in 1998, and 2·6 to 4·6 mg in 1999. Seed germination ranged from 78·8% to 98·0% in 1997, 82·3 to 98·3% in 1998 and 77·8 to 98·3% in 1999. Seed number, PLS m?2, ranged from 675 to 1289 in 1997, 710 to 1550 in 1998, and 717 to 1179 in 1999. Among the ten cultivars evaluated for seedling vigour, seedling weight differed between planting depths and a significant cultivar by year interaction was observed. Seedling weight was highly correlated with seed weight at each seeding depth. The effect of increasing number of PLS m?2 on subsequent yield performance, although small, was consistently negative. These results indicate that target plant populations may be obtained more economically by adjusting seeding rates for seed size differences among cultivars and seed lots of annual ryegrass.  相似文献   

16.
Epichloë fungal endophytes colonize the intercellular space of aerial organs of their plant hosts without causing symptoms. These symbionts are known to improve the performance of their host grasses in some situations of biotic and abiotic stress, leading to the suggestion that they can be used to improve grass tolerance to contaminants. The grass Festuca rubra is a host of the endophyte Epichloë festucae. We used two half‐sib lines of F. rubra, each line composed of infected (E+) or endophyte‐free (E?) seeds, to study the effect of varying levels of arsenic (6, 12, 25, and 50 mg L?1), and of the endophyte in seed germination and radicle growth. The results showed that seed germination was not significantly affected by arsenic (As) levels lower than 25 mg L?1, indicating that this grass has a relatively high tolerance of As at the germination stage. The decrease in germination observed at 25 and 50 mg L?1 was due to increased seed mortality and to the reversible inhibition of the germination of viable seeds caused by As. The presence of the endophyte did not change the germination response to arsenic of one line, but affected negatively the germination of the other line. In contrast to the process of germination, radicles of E+ seeds of both lines were longer than those of endophyte‐free seeds. The results of this work indicate that Epichloë endophytes can affect the performance of some F. rubra genotypes when As is present in the soil.  相似文献   

17.
The total amount and the composition of varieties of all forage grass and clover seed delivered for farm use in Northern Ireland was monitored over the 25‐year period of 1980–2004. Total seed use in Northern Ireland declined from the 1980s to the 1990s but then stabilized despite isolated drops in sales associated with outbreaks of animal diseases. This profile was mirrored by similar declines in the rest of the UK. The survey revealed the annual volatility of the market and its sensitivity to changes in government financial support, to changes in farm practice and farm incomes. Examination of the data on the grassland area under 5 years old showed them to be poor indicators of actual seed use. Levels of species use were very stable over the 25 years of the survey but reseeding of varieties of perennial ryegrass differing in maturity and ploidy type changed dramatically. When sufficient seed was available, selection of varieties complied with the contemporary recommended list ratings of agronomic value but in a few cases selection of varieties was determined by price. The current survey of seed sales provides a benchmark against which responses by farmers following the latest changes in the Common Agricultural Policy of the European Union can be measured.  相似文献   

18.
A rare stay‐green allele transferred from meadow fescue (Festuca pratensis L.) to perennial ryegrass (Lolium perenne L.) has improved both the colour of turf and the nutritive value of herbage. In this study its effect on shoot density and forage yield was assessed. Equivalent populations of perennial ryegrass were constructed with and without the stay‐green allele, following eight generations of backcrossing to perennial ryegrass. The stay‐green population, the normal population and the cv. AberStar were compared over two harvest years (2005 and 2006) in a field experiment with six application rates of N fertilizer (100, 200, 300, 400, 500 and 600 kg ha?1 annually). There were no significant interactions between level of N fertilizer and population in any of the traits measured. The mean annual dry‐matter (DM) yield over all populations and fertilizer levels was 6·45 t ha?1 lower in the second harvest year. Mean annual DM yields over all fertilizer levels of the normal population were higher than, or equal to, AberStar while those of the stay‐green population were significantly (proportionately 0·10–0·13) lower than the normal population. In 2005, the mean total yield of N in the herbage of the stay‐green population was 0·09 lower than that of the normal population and the mean concentration of N over all harvests was 1·5 g kg?1 DM higher. The shoot density of the stay‐green population after the last harvest in November 2006 was 0·18 lower than that of the normal population (3689 and 4478 shoots m?2 respectively).  相似文献   

19.
Plant breeding has developed perennial ryegrass varieties with increased concentrations of water‐soluble carbohydrates (WSCs) compared with conventional varieties. Water‐soluble carbohydrates are major metabolic and storage components in ryegrass. Therefore, if perennial ryegrass herbage is allowed to grow to greater heights it should contain higher water‐soluble carbohydrates concentrations, for example as under rotational grazing rather than continuous grazing by livestock. This study investigated this hypothesis and measured the performance of lambs grazed rotationally and continuously. Replicated plots of the variety AberDart (bred to express high WSC concentrations) or the variety Fennema were grazed by a core group of ten male Cheviot lambs for 10 weeks. Lambs were weighed and replicate forage samples were taken every 7 d. Concentrations of WSC in AberDart herbage were significantly (P < 0·05), but not substantially, higher than those in Fennema herbage. Rotational grazing did not increase the differential in WSC concentration between the AberDart and Fennema varieties. However, there was a tendency (P = 0·07) for lambs rotationally grazing the AberDart swards to have a higher final live weight than lambs grazing the Fennema swards. Overall, lamb performance was increased when either perennial ryegrass variety was rotationally rather than continuously grazed (P < 0·001).  相似文献   

20.
Adequate seed production is essential for cultivar success in perennial ryegrass turf and forage industries, but improvement is limited by the complexity of yield components and low-rank correlations between selection and production environments. This study examined seed yield components among 20 perennial ryegrass entries in both spaced plantings (selection environment) and swards (production environment) at two locations in Minnesota. Competitive (23 plants/m2) and non-competitive (3 plants/m2) spaced-plant nurseries were tested. Competitive spaced-plant total yield was highly correlated with sward yield (rs = 0.64 and 0.66, p < 0.01) at both locations, whereas the non-competitive environment showed no correlation. Structural equation modelling (SEM) was used to explore the indirect and direct relationship of fall vegetative growth, winterkill, and yield components on total seed yield in all environments. Fertile tiller number (spikes plant−1/m−2) exhibited both strong direct and indirect influence on total seed yield in all environments. However, the importance of fertile tiller number in the SEM was reduced with increased plant competition. The SEM showed that both weight per spike and seed yield per spike influenced total yield in spaced plants; however, neither consistently predicted total sward yield. The ratio of these two traits (g seed spike−1/g spike−1) gave an index of fertility that was easy to measure and had a superior correlation with sward yield at two locations (rs = 0.81 and 0.54, p < 0.05) when spaced plants were under competition. Results suggest that increasing competition in spaced plantings and selecting for spike fertility may more accurately identify superior plant material compared to lower competition environments.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号