Dactylis Glomerata Cv Research Articles

Screening of biomass production of cultivated forage grasses in response to mycorrhizal symbiosis under nutritional deficit conditions

AbstractArbuscular mycorrhizal fungi (AMF) colonize the root systems of most natural grassland species and usually increase plant growth by enhancing nutrients provision. This effect on growth responses of cultivated forage grasses is scarcely known, particularly under nutritional deficit conditions. We examined total biomass production, aboveground and belowground biomass and tillering of three temperate and three tropical cultivated forage grasses. Seedlings of each species were inoculated with a mixture of mycorrhizal fungi and later grown for 5 months under nutritional deficit conditions. The mycorrhizal symbiosis promoted aboveground and belowground biomass production in five out of six grass species. Grass species differed in their mycorrhizal responsiveness: tropical grasses (Panicum coloratum cv. Klein = Brachiaria brizantha cv. Marandú > Paspalum dilatatum cv. Primo) responded better than temperate (Festuca arundinacea cv. Royal > Agropyron elongatum cv. Hulk), while the temperate Dactylis glomerata cv. Porto did not respond to AMF inoculation. In four of the species, the changes observed in aboveground biomass were explained by the total number of tillers, while, in P. dilatatum, changes were accounted for by the individual weight of mature tillers. On the whole, the screening of cultivated forage grasses revealed that tropical grasses were highly responsive to mycorrhizae, in contrast to a lower effect on the growth of temperate grasses.

Silage fermentation characteristics of grass species grown under two nitrogen fertilizer inputs and harvested at advancing maturity in the spring growth

AbstractThree of the main management factors affecting herbage chemical composition pre‐ensiling are plant species, rate of nitrogen (N) fertilizer application and stage of maturity at harvest. This study investigated the effects of N fertilizer input and harvest date in the spring growth on the fermentation characteristics, dry matter recovery and aerobic stability of silages prepared from five common grass species. Perennial ryegrass (Lolium perenne cv. Gandalf), Italian ryegrass (Lolium multiflorum cv. Prospect), tall fescue (Festuca arundinacea cv. Fuego), cocksfoot (orchardgrass, Dactylis glomerata cv. Pizza) and timothy (Phleum pratense cv. Erecta) were grown under two inorganic N fertilizer inputs (0 and 125 kg N ha−1), harvested at five dates in the spring growth (fortnightly from 12 May to 7 July; Harvests 1 to 5, respectively) and subsequently ensiled in laboratory pipe silos for a period of 100 days. The ryegrass and tall fescue silages exhibited a lactic acid dominant fermentation and showed little evidence of secondary clostridial activity. In contrast, the challenge to preservation proved greater for the timothy (Harvests 1 and 2) and cocksfoot (Harvests 1 and 5) herbages, with the high pH (>4.2) and high butyric acid (>10 g kg−1 dry matter) and ammonia‐N (>100 g kg−1 N) concentrations being indicative of secondary clostridial activity during storage. Despite the effects on herbage chemical composition prior to ensiling being indicative of a greater challenge to preservation, there was little effect of fertilizer N on the extent or direction of fermentation. Although the Italian ryegrass herbage avoided significant clostridial activity, this herbage incurred the greatest dry matter losses during ensiling. This was particularly evident at early harvest dates suggesting yeast fermentation of sugars, which were surplus to the requirement for a lactic acid dominant fermentation.

Aclimatação morfológica de forrageiras temperadas a padrões e níveis de sombreamento

As características morfológicas do azevém-perene (Lolium perenne cv. Nui), dátilo (Dactylis glomerata cv. Vision) e trevo-vermelho (Trifolium pratense cv. Pawera) foram avaliadas em resposta a quatro níveis (0, 25, 50 e 75%) e dois padrões de sombreamento (contínuo e alternado), sob três períodos de crescimento (estabelecimento, primeira e segunda rebrotação), na Nova Zelândia, com o objetivo de avaliar as formas de adaptação de diferentes espécies às mudanças no ambiente luminoso. O estudo foi conduzido em delineamento experimental de blocos completos casualizados, com três repetições, entre janeiro e outubro de 2004. A maioria das medidas morfológicas foi afetada pelos níveis de sombreamento. A área foliar específica foi a variável morfológica que variou mais consistentemente em resposta aos níveis de sombreamento, com aumento de 22 a 79% entre as forrageiras. As adaptações morfológicas do dátilo foram as que mais se relacionaram à tolerância ao sombreamento, enquanto as do azevém-perene foram mais relacionadas à expansão da sua área foliar individual. A faixa de sombreamento entre 25 e 50% pode ser considerada a de maior aclimatação morfológica das forrageiras para compensar a restrição luminosa.

Grazing preferences by dairy cows for 14 forage species

The objective of this study was to quantify the grazing preference of dairy cows for eight grass, four legume and two herb species in eight seasons over 2 years. All species were grown at the same site, under the same climatic conditions, and with soil moisture and nutrient availability being non-limiting to plant growth. The forage species evaluated were cocksfoot (Dactylis glomerata cv. Kara H0265), perennial ryegrass (Lolium perenne cv. Bronsyn), short rotation ryegrass (Lolium multiflorum cv. Concord), fescue (Festuca arundinacea cv. Advance Maxp.), phalaris (Phalaris tuberose cv. Holdfast), paspalum (Paspalum dilatatum cv. Poir. Common), kikuyu (Pennisetum clandestinum cv. Whittet), prairie grass (Bromus willdenowii cv. Matua), lucerne (Medicago sativa cv. Sceptre), persian clover (Trifolium resupinatum cv. Maral), red clover (Trifolium pretense cv. Astred), white clover (Trifolium repens cv. Kopu II), chicory (Cichorium intybus cv. Grouse) and plantain (Plantago lanceolata cv. Tonic). The 14 forage species treatment plots were laid out in a completely randomised block design with three replicate blocks. The treatment plots were around the circumference of a circle so that the three cows used in each test had unbiased access to all forage species within the blocks. The tests comprised observing the forage being grazed at 10-s intervals for 1 h. The cow preference was recorded as time (min) spent grazing on each forage species. Three Holstein Friesian dairy cows of similar dominance were selected and had grazed all 14 forage species before tests. Cows were fed to requirements before each test so that they would be selective in choice of forages. The most preferred species over the whole year was prairie grass followed by kikuyu and then white clover, despite the fact that kikuyu was not available in winter. Fescue was the least preferred grass species. The mean grazing times for prairie grass and kikuyu during the 1-h test periods of grazing was 11.6 and 10.5 min, respectively. White clover and lucerne were the most preferred legumes (9.6 and 9.0 min, respectively), whereas chicory and plantain were little consumed (3.5 and 3.2 min, respectively). A prediction equation comprising water soluble carbohydrates (WSC%) and nitrate-nitrogen [NO3-N (g/kg DM)] over all seasons and forage species accounted for more variation in cow preference than any other single or combination of variables measured: cow preference [time (min) on plots] = 1.86 + 0.67 WSC% – 1.9 NO3-N (g/kg DM) (r2 = 0.76; s.e. = 2.22; n = 109). The results indicate that the relative palatability of forages can be reasonably well predicted from WSC% and NO3-N concentration, having a positive and negative effect on cow preference, respectively. The prediction equation was improved for groups of species if neutral detergent fibre (NDF%) was included: grasses, cow preference [time (min) on plots] = 24.5 + 0.42 WSC% – 1.31 NO3-N (g/kg DM) – 0.39 NDF% (r2 = 0.87; s.e. = 1.62; n = 57); legumes, cow preference [time (min) on plots] = 3.02 + 0.98 WSC% – 2.15 NO3-N (g/kg DM) – 0.08 NDF% (r2 = 0.92; s.e. = 1.38; n = 36); and herbs, cow preference [time (min) on plots] = 19.41 + 0.22 WSC% – 1.74 NO3-N (g/kg DM) – 0.69 NDF% (r2 = 0.53; s.e. = 1.81; n = 19).

Trangie wallaby grass [Austrodanthonia caespitosa (Gaudich.) H.P. Linder

Trangie wallaby grass, Austrodanthonia caespitosa (Dc1), is a composite of wild ecotypes collected from western New South Wales. A. caespitosa is a widespread native grass adapted to a broad range of environmental conditions but is particularly suited to low rainfall (300–450 mm) areas of south-eastern Australia. In this region, this cultivar has a demonstrated superior persistence to its close relative A. richardsonii (Cashmore) H.P. Linder cv. Taranna and the widely used pasture species, phalaris (Phalaris aquatica cv. Sirolan) and cocksfoot (Dactylis glomerata cv. Currie). This superior persistence was apparent in its ability to recruit new seedlings, even under summer drought conditions. Trangie wallaby grass was maintained under seed increase for 5 years at Trangie Agricultural Research Centre and subsequently at Dareton Agricultural and Advisory Station for 3 years.

Comparative defoliation tolerance of temperate perennial grasses

AbstractThe defoliation tolerance of cultivars of four temperate perennial pasture grasses, perennial ryegrass (Lolium perenne, cv. Yatsyn1), phalaris (Phalaris aquatica cv. Australian), tall fescue (Festuca arundinaceae cv. Demeter) and cocksfoot (Dactylis glomerata cv. Porto), was determined under controlled conditions over a period of 12 weeks. Undefoliated plants were compared with defoliated plants, where only half of one leaf was left intact at the initial defoliation, and leaf regrowth was harvested every 3–4 d. The growth responses measured were plant tiller number, dry weight, relative leaf regrowth rate, root:shoot ratio, sheath:stem ratio and specific leaf weight. All species showed morphological adaptations that potentially increased their ability to tolerate defoliation (e.g. increased allocation to shoot at the expense of roots and lower specific leaf weights) but cocksfoot was found to be the most defoliation‐tolerant and perennial ryegrass the least. The adaptation that favoured cocksfoot most strongly was high sheath:stem ratio, which, it is proposed, allowed it to maintain photosynthesis and a level of carbon supply sufficient to support regrowth throughout the experiment. The strategy of perennial ryegrass which favours leaf growth and leads to rapid leaf turnover rates made it particularly susceptible to defoliation under the conditions of this experiment. This highlights the likely importance of defoliation‐avoidance responses in explaining the well‐known grazing resistance of this species. Phalaris and tall fescue showed responses that were intermediate between the other two species. The importance of defoliation‐avoidance mechanisms and implications for grazing management are discussed.

Interactions between Widely Spaced Young Poplars (Populus spp.) and Introduced Pasture Mixtures

Silvopastoral systems involving poplars are widespread in rural landscapes in a number of regions of New Zealand. The effect of widely spaced trees of Populus nigra × P. maximowiczii, aged 8–11 years, on the growth and botanical composition of understorey pasture mixes was determined over 3 years at a southern North Island hill country site. Pasture mixes comprised existing pasture, and two introduced test swards comprising new grass (Agrostis capillaris, Dactylis glomerata, Lolium perenne) and legume (Lotus uliginosus, Trifolium repens) cultivars. Pasture accumulation beneath trees (6.6 t DM ha−1 year−1) was 23% less than open (unshaded, no trees) pasture (8.6 t DM ha−1 year−1) and differences in accumulation occurred between tree aspects (North and South sides of trees) when trees were foliated. In early spring, North plots produced 11–14% more herbage than South plots whereas in late summer, South plots produced up to 44% more herbage than North plots. Yield of both test swards (6.4 and 8.0 t DM ha−1 year−1) was not significantly different from that of the existing sward (7.4 t DM ha−1 year−1) but productivity varied between swards in spring and summer. One test sward included Lotus uliginosus cv. Grasslands Maku, and the sward produced 30% more DM than the other swards in mid-summer. Dactylis glomerata cv. Grasslands Wana comprised 37% of the DM of swards in which it was sown and was the most successful cultivar, followed by Grasslands Maku. Both cultivars are recommended for silvopastoral systems where pasture is lightly grazed.

Transfer of florigenic stimuli between tillers in photoperiodically split plants of Dactylis glomerata and Bromus inermis

The flowering response was studied in single plants of Dactylis glomerata cv. Apelsvoll and Bromus inermis cv. Løfar, with one half exposed to inductive short days (SD = 8 h) and the other half exposed to non‐inductive long days (LD = 24 h) during primary induction in a daylength tunnel. Although unsplit control plants of D. glomerata showed an absolute SD requirement for primary induction, 38% of the LD‐treated half‐plants headed if the opposite half‐plant had been exposed to SD. In B. inermis SD‐exposure of one side resulted in a 5‐fold increase in panicle production on the opposite LD side. These data suggest that flowering stimuli can be translocated from one tiller to another in these short–long day grasses, but it remains to be established whether this transport is specific or merely a result of carbohydrate flow to the LD sink of the photoperiodically split plants. Since LD exposure of the opposite half‐plant had relatively little influence on percent heading or panicle number on the SD side, the translocation of flowering inhibitors appeared to be more limited than that of flowering stimuli. A preliminary experiment using radiolabelled gibberellin confirmed that intertiller translocation of this primary induction inhibitor was virtually absent in D. glomerata and only amounted to 10–15% of the applied radioactivity in B. inermis. Although the specific roles of flowering stimuli and flowering inhibitors, including various gibberellins, remain to be elucidated, these data help to explain why it is often observed that late‐emerging tillers, which have not been directly exposed to inductive conditions of sufficient duration, become reproductive in these grasses.

Plant reserves of perennial grasses subjected to drought and defoliation stresses on the Northern Tablelands of New South Wales, Australia

The effects of defoliation intensity and drought severity on levels of water-soluble carbohydrate (WSC), fructan, and etiolated regrowth of 6 important perennial grasses were investigated. The experiment was conducted under a rain-out shelter at Armidale, NSW, Australia, using 6 perennial grass species (Phalaris aquatica cv. Sirosa, Festuca arundinacea cv. Demeter, Dactylis glomerata cv. Porto, Lolium perenne cv. Victorian, Microlaena stipoides cv. Shannon, and Austrodanthonia richardsonii cv. Taranna) subjected to 3 moisture regimes (non-stress moisture, and moderate and severe drought) and 2 defoliation intensities (moderate and severe) over 2 seasonal sequences (spring–summer and summer–autumn).The range in WSC, fructan, and etiolated regrowth of the species varied, with Festuca and Lolium having the highest WSC and fructan concentrations. Austrodanthonia had the lowest WSC concentration of the species. Unlike the introduced species, the natives did not store fructans. The species varied in their response to the treatments imposed. Festuca and Phalaris had the highest etiolated regrowth and showed the greatest effect of defoliation intensity. Etiolated regrowth appeared to be a sensitive measure of plant status, showing the fragile nature of some of the species.The effect of defoliation intensity and drought varied with season. Defoliation intensity had little effect on carbohydrate reserves of all species, except Festuca, during summer of the spring–summer experimental season. During the summer–autumn experimental season, severe defoliation reduced the rate of accumulation during the period December–April. Drought affected carbohydrate accumulation and utilisation. Carbohydrates that had been accumulated at the end of spring of the spring–summer experimental season in plants affected by drought were utilised during summer. However, if drought commenced in summer, carbohydrate accumulation continued for 120 days in all species studied, and 180 days in Lolium and Phalaris.Autumn appeared to be a period when plant reserves were particularly susceptible to stress. The importance of WSC, fructans, and etiolated regrowth as measures of plant reserves, and their role in persistence were discussed.

The effect of some herbicides on seed yield of six grass species - Short Communication

The tolerance to or phytotoxicity of selected herbicides and their impact on seed yield was investigated in six grasses grown for seed: Phleum pratense cv. Sobol (a), Festuca rubra cv. Táborská (b), Festuca pratensis cv. Otava (c), Poa pratensis cv. Slezanka (d), Arrhenatherum elatius cv. Medián (e) and Dactylis glomerata cv. Zora (f). All species were tolerant to Grodyl 75 WG (amidosulfuron 75%), (a) and (f) were tolerant to Grodyl plus (amidosulfuron 15 g/kg + isoproturon 600 g/kg) which was phytotoxic to the other grass species; all species were tolerant to Stomp 330 E (pendimethalin 330 g/l); Lintur 70 WG (triasulfuron 4.1% + dicamba 65.9%) was phytotoxic only to (c) while the other species were tolerant to it.

Persistence and tolerance to soil acidity of phalaris and cocksfoot in north-eastern Victoria

Persistence of Phalaris aquatica L. cv. Sirosa (phalaris) and Dactylis glomerata cv. Porto (cocksfoot) was evaluated for 5 pH treatments at 2 field sites on acidic soils. At one site (Beechworth) the soil was strongly acidic [pH(CaCl2) 14.21 to depth (80 cm) and contained concentrations of CaCl2-extractable aluminium (Al) >11 �g/g. At the other site (Lake Rowan) the soil pH (0-10 cm) was 5.0 and A1 concentrations were 4 �g/g. At Beechworth, lime incorporated at 5.5 t/ha improved establishment of phalaris but plant density declined, and by 30 months after sowing, phalaris plant densities were similar to treatments receiving no lime. Establishment of cocksfoot was less affected by lime application than phalaris, and plant densities were similar to those of phalaris by 26 months after sowing. However, there were no differences between pasture species where no lime was applied. Considerable re-establishment of cocksfoot seedlings occurred regardless of soil treatment. Despite the reported relative sensitivity of phalaris to Al in solution culture experiments, at Beechworth phalaris had more root development at depth than cocksfoot or annual pasture. Although concentrations of Al in the subsoil were high, the perennial deep root system of phalaris may give it an advantage over cocksfoot in terms of survival over summer. A larger root system at depth may give phalaris greater potential than cocksfoot for reducing nitrate leaching and soil acidification. On less acidic soils at the Lake Rowan site, lime application did not affect establishment of either phalaris or cocksfoot. Phalaris had greater persistence than cocksfoot at Lake Rowan. Dry summer conditions at Lake Rowan were the likely cause of poor persistence of cocksfoot. More drought-tolerant cocksfoot cultivars are required if this species is to be a useful perennial grass for pastures in ley cropping areas of Victoria and southern New South Wales.

Yield responses to lime of phalaris, cocksfoot, and annual pastures in north-eastern Victoria

Yield responses of 3 mixed grass-clover pastures [Phalaris aquatica L. cv. Sirosa (phalaris), Dactylis glomerata cv. Porto (cocksfoot), and annual grass based Trifolium subterraneum L. cv. Trikkala (subterranean clover) pastures] were measured over 5 soil pH treatments at 2 sites in Victoria. One site (Beechworth) was strongly acidic [pH(CaCl2) < 4.21 to a depth of 40 cm and contained high concentrations of soil aluminium (Al). At the other site (Lake Rowan), yield responses to lime application had been measured previously, but only in Al-sensitive wheat cultivars. At Beechworth, pasture yield responses to lime were not consistent but. when observed. occurred in autumn and winter in all 3 pasture types. Phalaris pastures showed yield increases more often than cocksfoot and annual pastures. Low magnesium and calcium concentrations may have limited dry matter production, although yields were reasonable on all treatments. Where lime was applied, growth responses may have been due to alleviation of Al toxicity. At Beechworth, pasture yield was increased where lime increased pH from 4.2 to 4.6 and decreased soil Al (measured in 10 mmol CaCl2/L) from 11 to <3 �g/g soil. Herbage manganese concentrations were not high in phalaris and subterranean clover, and cocksfoot manganese standards were not available. At Lake Rowan (pH 4.7, Al <1 �g/g), no growth responses to lime were seen in any pasture treatment, and annual grass based pastures sometimes had higher yields than phalaris and cocksfoot pastures. On strongly acidic soils such as at Beechworth, incorporation of lime prior to pasture establishment should be considered. Perennial grasses may reduce further soil degradation through acidification. Soil A1 concentrations are commonly lower in ley-cropping areas, and the inclusion of perennial grasses in ley pastures requires further evaluation.

The effect of differences in intensity and frequency of defoliation on the growth of Phalaris aquatica L. and Dactylis glomerata L

The response of phalaris (Phalaris aquaticu cv. Sirosa, Sirolan and Seedmaster) and cocksfoot (Dactylis glomerata cv. Currie) to 2- or 4-weekly cutting at heights of 2 or 7 cm was compared in a glasshouse experiment. Treatments were imposed over a period of 16 weeks.Dry matter production was greatest under the most lenient defoliation regime (4 week17 cm) and least under the most severe defoliation regime (2 week12 cm). Differences in harvested dry matter per tiller and leaf area per pot among cultivars increased with increasing leniency of defoliation. There were significant cultivar x cutting frequency x cutting height interactions for total winter leaf and spring stem production. Harvested dry matter from Sirosa and Sirolan was greater than that from Seedmaster under 4-weekly cutting, although differences in harvested dry matter per tiller were evident under all cutting regimes. Currie cocksfoot consistently maintained higher tiller numbers than the phalaris cultivars, but leaf, stem and leaf area production per tiller were generally ranked Sirolan > Sirosa > Seedmaster> Currie. When reproductive tillers were decapitated, Sirolan and Sirosa tended to produce more new tillers than Seedmaster under frequent cutting. More crown buds were found at the base of Sirolan tillers than on those of other phalaris cultivars, but the number of buds was reduced more on Sirolan with increasing severity of defoliation than on other cultivars. It is postulated that Sirolan and Sirosa may benefit from spelling in spring, and defoliation to a higher residual herbage mass andlor sward height than Australian-Seedmaster type.

Effect of soil properties on the yield and persistence of Mediterranean perennial grasses in southern Western Australia

The effect of ten soil types on yield and survival of three perennial grasses, each mixed with volunteer annual species, was studied for three years under periodic grazing. Yields of cocksfoot (Dactylis glomerata cv. Currie), phalaris (Phalaris aquatica cv. Australian) and tall fescue (Festuca arundinacea cv. Melik) were higher on a gravelly yellow podzolic soil than on other types; phalaris also yielded well on a red podzolic soil. Analysis by multiple linear regression showed that the yield of all sown grasses was high when perched water of the A and upper B horizons was recorded early in winter and sustained until late spring. High gravel content in the A horizon improved cocksfoot and fescue yield and depressed that of phalaris. The high gravel content was associated with increased gravel and decreased water retention of the top of the B horizon at 15 bars. Higher texture classes in the A horizon tended to depress yields of cocksfoot and fescue with no apparent effect on phalaris. The higher texture classes of the clay and clay loam soils tended to decrease general root penetrations. Cocksfoot and phalaris were more productive on shallow than on deep A horizon soils, but fescue yield was not affected by this soil property. Yields of the species can be estimated accurately from regression equations based on three or four soil properties. The results suggest options for selecting perennial grasses suitable for specific soil types among the red earth and red and yellow podzolic groups in the South Western Region of Western Australia. The central problem is that cocksfoot, phalaris and fescue can yield well but do not do so on all soil types.

PLANT ROOT GROWTH IN ACID ANDOSOLS FROM NORTHEASTERN JAPAN

This study was conducted to determine the properties of selected Andosols from northeastern Japan and the factors affecting the root growth of burdock, Arctium lappa cv. Takinogawa; barley, Hordeum vulgare cv. Norin-24; and orchard grass Dactylis glomerata cv. Kitamidori grown on these soils in a greenhouse. According to the clay mineralogical composition, the Andosol samples were divided into chloritized 2:1 mineral soils and allophane-imogolite1 soils. All the samples were poor in exchangeable bases, showed pH(H2O) ranging from 4.6 to 5.1, and were rich in reactive aluminum, as indicated by high pH(NaF), existence of large amounts of dithionite-citrate-soluble aluminum, and high phosphate absorption. On the other hand, a wide variation of exchange acidity Y1, determined by the titration of 125 ml of N KCl extract (soil: N KCL = 100:250) with 0.1 N NaOH, was observed; this was very large for chloritized 2:1 mineral soils and negligibly small for allophane-imogolite soils. Root growth of the test plants was reduced in chloritized 2:1 mineral soils, but not in allophane-imogolite soils. Morphological observation and aluminon test of the plant roots showed that aluminum toxicity occurred only in chloritized 2:1 mineral soils, even though all the soils contained large amounts of reactive aluminum and showed pH(H2O) range of 4.6 to 5.1. The degree of reduction of the root yields and the degree of aluminon reaction of aluminum-injured roots were in this order: burdock > barley > orchard grass. Examination of the properties of the soils sampled suggested that exchange acidity Y1 defined by Daikuhara (1914) was a realistic measure of aluminum toxicity potential in Andosols from northeastern Japan.

THE EFFECTS OF AIR POLLUTION ON PLANT GROWTH WITH SPECIAL REFERENCE TO SULPHUR DIOXIDE. III. GROWTH STUDIES WITH LOLIUM MULTIFLORUM LAM. AND DACTYLIS GLOMERATA L.

Summary Lolium multiflorum cv. S22 and Dactylis glomerata cv. S143 were grown in a sealed glass chamber, force‐ventilated with ambient SO2‐polluted air and the yields compared with those of control plants grown in a second chamber receiving filtered air, free of SO2 and particulates. Shoot dry weight of both species was reduced by 30 to 40 % after 8 to 10 weeks in unfiltered air containing mean SO2 concentrations of 50 to 90 μg m−3, growth reductions being readily detectable after 3 weeks from transplanting seedlings to the chambers. The productivity of L. multiflorum was only marginally depressed (c. 10 %) by late summer SO2 levels in the range 10 to 50 μg m−3. It is suggested that grass plants may be particularly susceptible to SO2 pollution during the early growth phase following germination when aerodynamic resistance is low and relative growth rate maximal. The possibility that environmental factors other than SO2 pollution contributed to the inhibitory effect of the unfiltered air treatment is discussed.

Rumen volatile fatty acids on six pasture species and relations with digestibility, voluntary intake and chemical composition

The total concentration and the relative proportions of the volatile fatty acids (VFA) were measured in rumens of sheep fed 78 single species pasture samples. The pastures consisted of regrowths of white clover (Trifolium repens cv. Grasslands Huia), Manawa regrass (Lolium perenne x multiflorum cv. Grasslands Manawa), Ariki ryegrass (Lolium (multiflorum x perenne) x L. perenne cv. Grasslands Ariki), perennial ryegrass (Lolium perenne cv. Tasmania No. 1) , Currie cocksfoot (Dactylis glomerata cv. Currie) and Apanui cocksfoot (Dactylis glomerata cv. Grasslands Apanui), cut eight times between May, 1969 and August, 1970. Sheep fed cocksfoot had lower VFA concentrations, higher proportions of acetate (HAc) and lower proportions of butyrate (HBu) than sheep fed white clover and ryegrass (P < 0.05). They also had lower proportions of propionate (HPr) than sheep fed ryegrass (P < 0.05). Sheep fed white clover had higher proportions of valerate (HVa) than those fed the grasses (P < 0.05). There were no significant (P < 0.05) seasonal differences in total VFA concentration but HAc was lowest with spring pasture (P < 0.05) and HBu was lowest with autumn pasture (P < 0.05). Total VFA concentration was positively related to digestibility (DMD) (r = +0.52, P < 0.01) but species differences occurred and at similar DMD, white clover produced higher concentrations than ryegrass (P < 0.05) which produced higher concentrations than cocksfoot (P < 0.01). The overall relation between total VFA and intake (DMI) was weak but seasonal differences occurred and at similar levels of DMI, winter pasture produced higher VFA concentrations than spring-summer pasture (P < 0.01). The proportion of HPr was positively related to VFA concentration (r = +0.53, P < 0.01) and to water soluble carbohydrate (WSC) content (r = +0.51, P < 0.01) and relations with DMD and DM1 were weak and non-significant (P > 0.05).

Control of the biennial thistle, Onopordum, by amitrole and five perennial grasses

Experiments carried out from 1959 to 1967 Rear Goulburn in the southern tablelands of New South Wales were designed to test the relative effectiveness of the perennial grasses, Bromtls inermis C.P.I.7073, Dactylis glomerata CV. Brignoles, Festuca arumdinacea CV. Demeter, Lolium perenne CV. Victorian, and Phalaris tuberosa CV. Australian in seasonal control of the biennial thistle Onopordum. The grasses were sown in autumn and in spring. Amitrole (0.5 lb active ingredient an acre) was used to suppress the thistles in the first season. Harvests of the autumn- and spring-sown plots in December 1959 showed large decreases in yield of thistles and increases in yield of grass due to spraying, but in two or three years these effects had disappeared. Dactylis glomerata and Lolium perenne were the most productive grasses at the December 1959 harvest, but the former gave better thistle control. Harvests of the autumn-sown plots in October 1963 showed that Dactylis glomerata and Festuca arundinacea gave the best control of thistles, while in 1966 Dactylis glomerata had almost disappeared and was no longer effective. In 1966, Festuca arumdinacea and Phalaris tuberosa were the only grasses giving effective thistle control. Harvests of the autumn-sown plots in October 1960 showed an increase in yield of the sown grasses but not of the thistles to 30 and 60 lb nitrogen applied in August 1960 before active spring growth of thistles began. Despite a stronger growth of thistles in the first season, the spring-sown grasses showed essentially the same pattern of thistle control as the autumn-sown grasses throughout the remainder of the trial period. Root distribution studies in 1961 showed that Dactylis glomerata had a much higher proportion of its roots in the top six inches than either Festuca arundinacea or Phalaris tuberosa. The greater surface rooting habit of Dactylis glomerata was considered to be important in determining its early success in thistle control, its exclusion of Trifolium subterraneum and its apparent susceptibility to a drought experienced in 1964-65. On the other hand, the deeper rooting habit of Festuca arundinacea and Phalaris tuberosa was taken to explain their persistence and long-term success in thistle control.