Bromus Catharticus Research Articles

On the origins of the tetraploid Bromus species (section Bromus, Poaceae): insights from internal transcribed spacer sequences of nuclear ribosomal DNA.

The internal transcribed spacer (ITS) region of nuclear ribosomal DNA from 22 diploid and tetraploid annual Bromus species of section Bromus (Poaceae) and three species belonging to other Bromus sections, Bromus catharticus (section Ceratochloa), Bromus anomalus (section Pnigma), and Bromus sterilis (section Genea), were investigated by PCR amplification and direct sequencing. The length of the ITS-1 region varied from 215 to 218 bp, and that of the ITS-2 region from 215 to 216 bp, in the species analyzed. ITS-1 was more variable and provided more informative sites (49) than ITS-2 (32). No variation was encountered within species. In pairwise comparison among species of section Bromus, sequence divergence ranged from 0.0 to 8.0% for the combined ITS-1 and ITS-2 regions. Parsimony analysis using Avena longiglumis and Hordeum vulgare as outgroups resulted in well-resolved phylogenetic trees and showed that section Bromus is monophyletic according to the species analyzed outside of the section. The analysis clarified the phylogenetic relationships among monogenomic (diploid) species. Introduction of the allotetraploid species did not change the general topology of the trees obtained using only the diploid species. Although some tetraploid-diploid species relationships will have to be clarified with faster evolving markers, the ITS sequences are shown to be useful for assessing evolutionary relationships among closely related Bromus species, as well as for clarifying taxonomic problems in previously controversial cases (e.g., Bromus alopecuros and Bromus caroli-henrici). New hypotheses are proposed concerning the origin of several allotetraploid species. For example, it is shown that the tetraploid Bromus hordeaceus diverged earlier than all other species of section Bromus, excluding the diploid B. caroli-henrici, which is found to be basal in this group. The tetraploid Bromus arenarius, which was considered a hybrid between sections Bromus and Genea, and the tetraploid Bromus adoensis are sister taxa within section Bromus; they belong in a weakly differentiated clade with the diploids Bromus brachystachys, Bromus japonicus, Bromus squarrosus, Bromus arvensis, and Bromus intermedius.

Herbage yield, tiller number and root system activity after defoliation of prairie grass (Bromus catharticus Vahl)

The effects of defoliation upon root and shoot systems of prairie grass (Bromus catharticus Vahl) were examined in both field and pot studies. The varieties used were 78–32 (HY), a high‐yielding variety; 79–42 (LY), a low‐yielding variety; and the commercial variety Grasslands Matua. In the field, the presence of roots in early and late spring was estimated by measuring uptake of [32P]phosphate by roots; herbage yields and tiller numbers were recorded. In a pot study, root and shoot dry‐matter (DM) yields were analysed. In the field, roots were detected to a depth of 1·2 m. After defoliation to a height of 0·1 m, root presence decreased more than 50% at depths of 0·6 m for LY and 1·0 m for Matua in early spring and at several depths for each variety in late spring. After a second defoliation, the apparent growth rate of shoots decreased by 35% in relation to the first regrowth period. In pots, shoot DM and root DM of control plants (undefoliated) had the following allometric relationship of the form: In (shoot DM) = 0·61 + 1·14 ln (root DM) (r2= 0·81). After defoliation, compared with undefoliated controls, the relative growth rate of shoots and total herbage yields were higher, but root and stubble DM were lower in all three varieties. Pooled root DM means were 10·3 and 6·8 g plant−1 and pooled stubble DM means were 12·7 and 7·6 g plant−1 for control and defoliated plants respectively. HY produced heavier tillers than LY, pooled means being 0·94 and 0·53 g DM tiller−1 (field study) and 3·44 and 2·05 g DM tiller−1 (pot study) for HY and LY respectively. HY had 5–6 green leaves per tiller, whereas LY had 3–4. Developed green leaves were heavier in HY (58 g m−2) than in LY (48 g m−2). It is suggested that differences in both leaf parameters may be related to higher herbage yields for HY than LY.

Confocal imaging of exine as a tool for grass pollen analysis

A new method which utilises confocal optical imaging has been developed which can be expected to improve grass pollen analysis. Confocal microscopy, in reflection mode, was used to examine the exine morphology of unacetolysed pollen grains from the following species of common wild grasses: Paspalum dilatatum, Setaria gracilis, Bromus catharticus, Daclylis glomerata, Lolium perenne, Poa pratensis, and Phalaris aquatica. Variations in the surface texture patterns, similar to those hitherto only seen by scanning electron microscopy, were visualised. In contrast to the latter method, specimen preparation for this confocal microscopy based technique was characterised by its simplicity, permitting the use of fresh and chemically untreated pollen grains. This confocal imaging technique, with its capacity for optical sectioning of specimens, offered the additional advantage of allowing the examination of the sub‐surface exine layers as well as the surface morphology of the pollen grains. Furthermore, three‐dimensional reconstruction of these optical sections enabled visualisation of the identified sculptural and structural exine elements and layers. A number of differences in these patterns were found, which indicate that confocal microscopy, in combination with image analysis, may enable finer taxonomic distinctions to be made than those currently provided by other light microscope based methods.

Fall Harvest Management Effects on ‘Grasslands Matua’ Prairie Grass Quality

AbstractForage production of ‘Grasslands Matua’ prairie grass [Bromus catharticus M. Vahl; syn. B. unioloides Kunth, B. willdenowii Kunth] (Matua, for short) during the fall months is excellent, but highly management dependent. Unfortunately, fall harvest management effects on the quality of this grass are relatively unknown. Our objectives were to determine the effects of fall harvest management on forage quality of Matua prairie grass during the fall and following spring. Two field experiments were conducted on Hagerstown silt loam soil (fine, mixed, mesic Typic Hapludalfs). Experiment 1 addressed date of fall harvest and residual stubble height; Experiment 2 addressed frequency of fall harvest and residual stubble height effects on forage quality in the fall and spring. Delaying fall harvest of Matua prairie grass caused forage crude protein (CP) content to decline by about 30%; however, delaying fall harvest had no or little effect on acid‐detergent fiber (ADF), neutral‐detergent fiber (NDF), or in vitro dry matter digestibility (IVDMD). Grasslands Matua quality in the spring was unaffected or inconsistently affected by fall harvest management. Delaying harvest of Matua prairie grass in the spring reduced forage quality but not to the extent reported for other cool‐season forage grasses. Our findings indicate that Matua offers considerable latitude in fall and spring harvest management with regards to obtaining quality forage; however, these finding should be considered along with previous findings that fall harvest management has a large effect on winter survival of Matua.

Effects of the Systemic Flower Infecting-Smut Ustilago Bullata on the Growth and Competitive Ability of the Grass Bromus Catharticus

Effects of the Systemic Flower Infecting-Smut Ustilago Bullata on the Growth and Competitive Ability of the Grass Bromus Catharticus

Canopy Management Influences on Cool‐Season Grass Quality and Simulated Livestock Performance

AbstractInadequate energy intake across the grazing season can be a major limitation to performance of grazing ruminants. A small‐plot experiment was conducted to determine the effect of repeated defoliation, based on canopy height and on the quantity and quality of tall fescue × perennial ryegrass (Festuca arundinacea Schreb. × Lolium perenne L.) hybrid, orchardgrass (Dactylis glomerata L.), and prairie grass (Bromus catharticus M. Vahl) in the Central Appalachian Region of the USA. Energy determined from herbage quality data was used to predict growing steer performance. Early and repeated defoliation (T50, 20‐cm canopy cut to 10‐cm residue; S50, 10‐cm canopy cut to 5‐cm residue; and T75, 20‐cm canopy cut to 5‐cm residue) of the grasses resulted in greater herbage crude protein (CP) (202, 226, and 189 g kg−1, respectively) and lower neutral detergent fiber (NDF) concentrations (591, 572, and 596 kg−1, respectively) compared with the hay management (hay harvested at early seed head emergence followed by T75 management; 152 g CP kg−1 and 620 g NDF kg−1). Cumulative metabolizable energy yield on a 1000‐ha basis tended to be highest for hay (62 138 MJ ha−1) and T75 (49 678 MJ ha−1), compared with S50 (40 373 MJ ha−1) and T50 (28 457 MJ ha−1) simply because of greater herbage mass. Greatest average daily gain was predicted when 250‐kg steers grazed T50 (0.81 kg d−1) compared with S50 (0.70 kg d−1) and T75 ( 0.71 kg d−1). Total number of grazing days per hectare was lowest for T50 (431 d), compared with S50 (580 d) and T75 (690 d). Total annual gain was greater for T75 (690 kg liveweight ha−1) management than for S50 (580 kg ha−1) or T50 (436 kg ha−1). Using herbage earlier in spring before maturation may compromise total herbage productivity, but should sustain a greater number of grazing days and livestock productivity for a given land area.

Lipid composition of grains from wild grasses

Physicochemical characteristics, fatty acid and sterol composition were studied in grains of Agropyron elongatum, Bromus catharticus, Festuca arundinacea, Stipa hyaline and Panicum maximum . The highest protein level was found in A. elongatum . Linoleic and palmitic acids were the predominant fatty acids in all species, β-sitosterol was by far the most prominent sterol component in all samples, while Δ 7 -stigmasterol was detected in only trace amounts.

Acidovorax avenae subsp. avenae . [Descriptions of Fungi and Bacteria

Abstract A description is provided for Acidovorax avenae subsp. avenae . Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Agropyron intermedium, A. trichophorum, Avena sativa, Bromus catharticus, B. marginatus, Camellia sinensis (may form a complex with Pseudomonas syringae pv. theae : 68, 955), Caryota mitis, Digitaria sanguinalis, Echinochloa crusgalli, Eleusine coracana, Euchlaena mexicana, Oryza sativa, Panicum hirsutum, P. miliaceum, Paspalum nutans, P. paniculatum, P. urvillei, Pennisetum americanum, Saccharum officinarum, Setaria italica, S. lutescens, S. viridis, Sorghum bicolor and Zea mays . DISEASE: Bacterial leaf blight of maize and sorghum, brown stripe of rice and red stripe of sugarcane. Symptoms in general consist of leaf streaks and stripes, which may extend into the sheaths. Occasionally a stalk rot develops. Symptoms are more severe on seedlings and immature plants. Discolouration of seeds can occur on rice. In fishtail palm ( Caryota mitis ), lesions are mainly at the leaf margin and brown/black with a chlorotic halo (Miller, 1992). In most cases conditions of high temperature and high relative humidity favour symptom development. GEOGRAPHICAL DISTRIBUTION: Comoro Is., Egypt, Ethiopia, Ivory Coast, Kenya, Madagascar, Mauritius, Malawi, Mozambique, Niger, Nigeria, Reunion, Sierra Leone, South Africa, Sudan, Tanzania, Uganda, Zaire, Zimbabwe, Bangladesh, Burma, Bhutan, Cambodia, China, India, Indonesia, Iran, Iraq, Japan, Korea, Malaysia, Nepal, Okinawa, Pakistan, Philippines, Sri Lanka, Taiwan, Thailand, Vietnam, Australia, Fiji, Guam, Papua New Guinea, Tahiti, Italy, Portugal, Turkey, Mexico, USA (Alabama, Arkansas, Florida, Georgia, Illinois, Hawaii, Kansas, Louisiana, MT, Nebraska, New York, Pennsylvania, Texas & Virginia), Barbados, Costa Rica, Cuba, Dominican Republic, El Salvador, Guadeloupe, Guatemala, Honduras, Jamaica, Martinique, Nicaragua, Panama, Puerto Rico, St. Kitts, Trinidad, Argentina, Brazil (Sao Paulo), Colombia, Guyana, Paraguay, Peru, Surinam, Uruguay, Venezuela ( CMI Map 511 ed. 1, 1976 & CMI Map 39 ed. 5, 1987). TRANSMISSION: The disease is largely thought to be seed borne. In rice, the bacterium is located between the glumes and the pericarp, or deeper in the seed (Shakya et al. , 1986). There is evidence to suggest that mature plants which survive infection in the seedling stage harbour latent infections. The bacterium can be found in 8-yr old rice seed samples stored at 5°C (Shakya et al. , 1985). The bacterium is not thought to survive well in soil or in plant debris. Alternative hosts such as Paspalum urvillei (Vasey grass) in Florida, USA have been noted as an inoculum reservoir in bacterial leaf blight of maize outbreaks (Shurtleff, 1973; 57, 4929).

Bromus catharticus: A New Host Record for Wheat Stem Rust in South Africa

<i>Bromus catharticus</i>: A New Host Record for Wheat Stem Rust in South Africa

Serological relationships of geminivirus isolates from Gramineae in Australia

Three distinct viruses, named chloris striate mosaic virus (CSMV), paspalum striate mosaic virus (PaSMV) and digitaria didactyla striate mosaic virus (DDSMV), have been identified among the five Gramineae‐infecting geminiviruses from Australia using polyclonal antisera. An isolate from Microlaena was confirmed as a strain of CSMV, and an isolate from Bromus catharticus was identified as PaSMV‐BC. Enzyme‐linked immunosorbent assay (ELISA) detected relationships between all but one of the viruses tested, the exception being miscanthus streak virus (MiSV) from Japan. The Australian viruses proved to be distantly related to similar viruses from Africa, digitaria streak virus (DSV) from Vanuatu, and wheat dwarf virus (WDV) from Europe. Three distinct groups of viruses from Africa, Australia and Europe were distinguished by phylogenetic analysis.

Voluntary intake and rumen digestion of a low-quality roughage by goats and sheep

SUMMARYPrairie grass (Bromus catharticus) straw (13·7 g N/kg DM) was fed ad libitum to six goats and seven sheep kept in metabolism cages at Palmerston North, New Zealand in 1986 and 1987.Goats had greater voluntary feed intake (VFI) (56 v. 36 g DM/kg W0·75 per day), greater apparent DM digestibility (36·8 v. 32·6%) and a larger rumen pool of DM and liquid (W0·75) than sheep. Goats also had greater apparent digestibility of fibre, especially of lignin, and greater rumen fractional degradation rates (FDR) of cellulose, hemicellulose and lignin. Goats had a higher rumen ammonia concentration (115 v. 80 mg N/l), lower rumen pH (6·73 v. 6·90), a smaller proportion of large particles and greater proportion of small particles in rumen contents than sheep. Passage through a 1 mm sieve was established as the threshold particle size to have a high probability of leaving the rumen in both goats and sheep. Voluntary water intake/unit DM consumed was lower in goats than in sheep and, whilst rumen fractional outflow rate (FOR) of water and particulate matter also tended to be lower in goats, the difference was not significant. Irreversible loss rate of rumen NH3 and the amount of N calculated as recycled to the rumen, both expressed as mg N/kg W0·75 per day, were greater for goats than for sheep.It was concluded that the ability of goats to maintain a higher rumen NH3, concentration than sheep, their larger rumen pool and the higher proportion of small particles in rumen contents were all contributing factors to their greater VFI and fibre digestion of this low-quality roughage.

Theoretical considerations in the estimation of rumen fractional outflow rate from various sampling sites in the digestive tract.

The digesta markers 103ruthenium phenanthroline (Ru-P) and 51Cr-EDTA were continuously infused into the rumen of young lambs offered clover hay ad lib. indoors or grazing pure species swards of either lucerne (Medicago sativa), white clover (Trifolium repens), ryegrass (Lolium perenne) or prairie grass (Bromus catharticus). Following the cessation of infusion the fractional outflow rate (FOR) of markers from the rumen was estimated from the rate of decline of marker concentration in rumen and abomasal digesta (Expt 1), abomasal digesta and faeces (Expt 2) and duodenal digesta and faeces (Expt 3). Estimates of FOR from the rumen were similar when based on rumen and abomasal sampling but estimates from abomasal and duodenal sampling were significantly higher than those from faeces. A simulation of a two-compartment model with variable FOR was performed to calculate faecal excretion curves following continuous marker infusion or the administration of a single marker dose into the rumen. Analysis of the descending portion of these theoretical faecal excretion curves yielded values of FOR from the rumen which differed from the values entered in the equations. The magnitude of the difference depended on the ratio of the values of FOR from the caecum and rumen entered in the equation. This suggested that the experimental variation observed in these young lambs was caused by the high FOR from the rumen in relation to the FOR from the caecum-large intestine.

Biological characteristics of grass geminiviruses from eastern Australia

SummaryTwo serotypes of chloris striate mosaic virus (CSMV), paspalum striate mosaic virus (PSMV) and geminiviruses infecting Bromus catharticus and Digitaria didactyla were investigated. Their field occurrence and experimental hosts are listed. Serial transmission data for CSMV by single Nesoclutha pallida show a minimum latent period of 12–14 h, and regular transmission with occasional breaks for up to 50 days. Cicadulina bimaculata did not transmit any isolates after plant feeding acquisition, but transmitted CSMV inefficiently after insect injection. The vector of PSMV was found to be a specific biotype of N. pallida which bred only on Paspalum spp. The rate of transmission of CSMV with the Chloris biotype of N. pallida and of PSMV with the Paspalum biotype reached c. 50% with single insects, but only when freshly‐infected source plants were used. Geminate particles were found in thin sections of leaf tissue infected with all four viruses, and partially purified preparations were made of three of these. In gel diffusion tests, the virus from Microlaena stipoides produced a spur reaction with CSMV, when reacted with CSMV antiserum. The B. catharticus and D. didactyla isolates failed to react serologically with CSMV, maize streak or Vanuatu digitaria streak viruses.

The effects of flowering and leaf area on sward growth in winter of temperate pasture grasses

Pasture growth rates in winter, in many regions are low, and this often sets the limit on the stocking rates possible on those pastures. This research was done to examine some of the reasons for the differences in productivity between grasses In winter. Eight perennial and two annual grasses were compared over three years in a field experiment, where mean daily air temperatures in winter averaged 5�C. Species separated into five groups. The largest yields, over winter from plots cut either in autumn or early winter, were obtained from Kangaroo Valley perennial ryegrass (Loliurn perenne) and Wimmera annual ryegrass (L. rigidurn). Their yields were significantly greater than from oats (Avena byzantina) and prairie grass (Bromus catharticus), which in turn were greater than mountain rye (Secale montanum) and Sirosa phalaris (Phularis aquatica); the next group were CPI 69358 perennial ryegrass, currie cocksfoot (Dactylis glomerata) and Australian Commercial phalaris, and least was CPI 68318 cocksfoot. Greater forage yield, within years, was obtained from grasses that switched into reproductive development early in winter rather than from a high leaf area index in swards prior to winter. Differences in yield between years were, though, related to differences in leaf area. The average sward net assimilation rates over winter were greater for ryegrass cultivars, and oats, than for the other species. Plots uncut from autumn had greater yields throughout winter but lower net assimilation rates. It was concluded that improved pasture yields in winter can be obtained by selecting or recommending grasses that commence reproductive development early. This effect would apply in most environments where temperate grasses and cereals are grown.

Ecology of Barley Yellow Dwarf Virus in South-East Queensland.

Transmission tests with Rhopalosiphum padi and R. maidis were used to assess incidence of barley yellow dwarf virus in cereal and grass specimens collected in surveys over the eastern Darling Downs and Lockyer district of Oueensland. Up to 20% incidence was found in randomly sampled, grazed oats, but incidence in wheat was less than 1%. Bromus catharticus was shown to be a perennial host of PAV and R. Padi. RMV incidence in Urochloa panicoides was up to 60% in early summer and Paspalurn dilatatum was a perennial host of RMV.

Germination and seedling growth of prairie grass, tall fescue and Italian ryegrass at different temperatures

We measured the effects of temperature on the germination, emergence and growth during early tillering of Italian ryegrass (Lolium multiflorum), prairie grass (Bromus catharticus) and tall fescue (Festuca arundinacea). Radicle emergence (the percentage of seeds with emerged radicles) and 'field' emergence (the percentage of seeds with shoots &gt; 1 cm long) were reduced at 35�C (constant, all lines), or 30/25�C (12/12 h, prairie grass and Tama Italian ryegrass only). All lines took longer to germinate at 15 and 10�C (constant) than at higher temperatures, and final percentage germination of tall fescue lines was lower at 10�C (constant) than at other temperatures. Italian ryegrass had the fastest shoot extension, and consequently the fastest 'field' emergence. Seed respiration rates were higher in fescue than in the other lines at 4 days from imbibition, and rates rose in all lines at 8 days. Over the first 20 days after sowing, growth rates were closely related (r = 0.87-0.99) to weights of seed and caryopses, when account was taken of perenniality (which was associated with relatively slow growth) and polyploidy (which was associated with growth faster than might be expected from seed size alone), and a multivariate relationship including temperature was developed (R2 = 0.88). Growth rates of shoots at 20 days after sowing were ranked Tama Italian ryegrass &gt; prairie grass &gt; Ucivex Italian ryegrass &gt; tall fescue, and 24/19 &gt; 21/16 &gt; 18/13 &gt; 30/25 &gt; 15/10�C. Growth during tillering, up to 42 days after emergence, was ranked Italian ryegrass &gt; prairie &gt; tall fescue and 21/16 = 18/13 &gt; 24/19 = 15/1O�C. Relative growth rates and relative rates of tillering were independent of temperature in Italian ryegrass, but were lower at 15/10 and 24/19 than at 21/16 and 18/13�C in prairie grass and tall fescue. Prairie grass had higher yield per tiller but lower tiller numbers than Italian ryegrass; tall fescue had both lower yield per tiller and lower tiller number. Italian ryegrass was therefore the species best adapted to variations in environment and competition at sowing.

Primary growth and regrowth responses of temperate grasses to different temperatures and cutting frequencies

Primary growth and regrowths of Italian ryegrass (Lolium multiforum), prairie grass (Bromus catharticus) and tall fescue (Festuca arundinacea), grown in glasshouses at temperatures ranging from 15/10 to 30/25�C, were measured when defoliated every 4 or 8 weeks. Prairie grass, tall fescue, Ucivex Italian ryegrass, and Tama Italian ryegrass each had different patterns of regrowth. Growth was fastest at 21/16 and 24/19�C in primary growth and at 15/10�C in regrowth, except for fescue which had fastest regrowth at 24/19�C. Frequent defoliation (every 4 weeks) halved the total dry matter yield harvested throughout the experiment. The mean number of tillers and leaves produced was halved by frequent defoliation and leaf area was reduced to one-quarter of that for plants defoliated every 8 weeks. Reproductive development was earlier in plants grown at lower temperatures and did not occur in those grown at 24/19 and 30/25�C. Primary growth of Italian ryegrass and prairie grass was faster than that of tall fescue. Yield and the number of tillers increased at successive regrowths under 8-week defoliation, but only Tama Italian ryegrass maintained its productivity under frequent defoliation owing to its ability to maintain a high tiller population and high individual leaf areas. Productivity of prairie grass was limited by low tiller number despite its high yield per tiller, and productivity of tall fescue was restricted by both low tiller number and low yield per tiller. The extent to which current growth was influenced by prior growth and, by implication, previous defoliation management differed between the grasses. For example, productivity in any regrowth of Tama was essentially independent of growth during the primary growth or previous regrowth periods, whereas regrowths of prairie grass were highly dependent on growth during previous regrowth periods.

Direct drilling tall fescue (Festuca arundinacea Schreb.) prairie grass (Bromus catharticus Vahl) and Italian ryegrass (Lolium multiflorum Lam.) into kikuyu and paspalum pastures

Italian ryegrass (Lolium multiflorum Lam.), prairie grass (Bromus catharticus Vahl) and tall fescue (Festuca arundinacea Schreb.) were direct-drilled into paspalum and kikuyu pastures at Camden (1980-83) and Bega (1 982) in New South Wales. Prior to sowing, pastures were either slashed or slashed and sprayed with herbicide. In 1980, paraquat (0.28 kg a.i./ha) and glyphosate (0.5 kg a.i./ha) were compared with slashing-only at a March sowing. In 1982 and 1983, glyphosate only was compared with slashing, and grasses were sown on four occasions at 5-week intervals from late January or mid- February to early June. Seedlings were counted and weights of individual seedlings were measured at about 5 weeks after sowing, and pasture yield and species composition were measured 10 weeks after sowing, at the end of winter, and on selected plots, in winter in the following year. In 1980, plant density and dry matter yield at the first harvest of prairie grass and tall fescue was better from plots treated with glyphosate than from those treated with paraquat or slashed-only. However, plant density and dry matter yield of ryegrass was unaffected by preparation. In 1982 and 1983, plant densities 5 weeks after sowing increased with the use of glyphosate, and with later sowing. Prairie grass was least sensitive to sowing time establishing similar populations of between 50 and 150 seedlings/m2 from February to May. Tall fescue only established satisfactory seedling populations (50 to 200 seedlings/m2) at April and May-June sowings with glyphosate; it required suppression of competition, and low temperatures for faster growth than kikuyu and paspalum. The use of glyphosate reduced total pasture production during the first 10 weeks from 5 to 3 t/ha, but the contribution of sown grasses was increased. Winter production was greatest from sowings in March and April. Italian ryegrass always produced significant quantities of dry matter at the first cut and in winter; tall fescue was never productive in the first year. Persistence of prairie grass and tall fescue from 1982 sowings until 1983 was good, and highest tiller densities of 300-400 and 800 tillers/m2 respectively occurred from April sowings with glyphosate. Between June and September 1983, prairie grass and tall fescue from these plots produced about 3 and 2 t/ha of dry matter respectively. As seedling vigour declined from Italian ryegrass to prairie grass to tall fescue, conditions required for successful establishment became more stringent. Persistence and production of perennials was excellent if sown at the right time to encounter favourable temperatures, and competition was suppressed. Mixtures thus established need to be assessed on a paddock scale under grazing to determine their final viability.

Growth of seedlings of prairie grass and tall fescue in small swards of kikuyu at different temperatures

Seeds of prairie grass (Bromus catharticus Vahl) and tall fescue (Festuca arundinacea Schreb.) were planted in established small swards of kikuyu (Pennisetum clandestinum Hochst ex Chiov.). Growth of the temperate seedlings and the subtropical grass sward was measured over a period of 59 days under four temperature regimes from 14/6 to 23/20�C (12/12 h). The capacity of the seedlings of the oversown temperate perennial grasses to establish in the sward of the subtropical kikuyu depended on temperature. At low temperature (mean daily temperature &lt; 1l�C) the seedlings grew faster than the kikuyu and became successfully established. At moderate temperatures (11-19�C) the relative growth rates of seedlings were comparable with the relative growth rates of kikuyu tillers, but the latter dominated due to a greater absolute growth rate. Stature was an important component in the inter-species competition, and the taller prairie grass grew much better in competition with kikuyu than did fescue. Temperatures above 20�C exceeded the optimum of the seedlings of the temperate species but not that of kikuyu, so that the sown species were at a disadvantage and kikuyu dominated the mixture. It is concluded that prairie grass and tall fescue can be established successfully only in swards of kikuyu when day temperatures are below 21 and 15�C respectively, unless kikuyu is suppressed for a long period. A herbicide may be an economical means of doing this.

Response of perennial ryegrass, prairie grass, and browntop to the growth retardant, mefluidide

Abstract The efficacy of the synthetic growth retardant mefluidide in reducing grass sward yield is affected by the interactions of plant species, chemical, and environmental factors. This field study examines the effect of mefluidide on the growth and development of 3 grass species; perennial ryegrass (Lolium perenne L.), prairie grass (Bromus catharticus Varth.), and browntop (Agrostis tenuis Sibth.). All 3 species were significantly retarded for up to 8 weeks by a single application of mefluidide at 0.5 kg/ha or higher. Both vegetative and reproductive development were suppressed by mefluidide. Some mefluidide-induced phytotoxicity was observed, particularly in the finer-leaved browntop species. In a second field experiment, the timing of mefluidide application was noted to have a significant effect on efficacy. Early spring applications during September were the most effective, although significant retardation of grass growth was also observed following later applications in October.