Growth, seed production and effect of defoliation in an early flowering perennial grass, Alloteropsis semialata (Poaceae), on Cape York Peninsula, Australia

2001 ◽  
Vol 49 (6) ◽  
pp. 735 ◽  
Author(s):  
Gabriel M. Crowley ◽  
Stephen T. Garnett
Keyword(s):  
Plant Growth ◽  
Seed Production ◽  
Perennial Grass ◽  
Soil Surface ◽  
Plant Size ◽  
Perennial Grasses ◽  
Wet Season ◽  
Cape York ◽  
Seed Dynamics

Alloteropsis semialata (R.Br.) A.Hitchc. is one of the first perennial grasses in monsoonal Australia to produce seed at the start of the wet season. Patterns of growth and seed production and seed dynamics of Alloteropsis semialata were examined in this study, along with the effects of partial defoliation. Growth of Alloteropsis semialata tussocks started with the first pre-wet-season rains, and was then interrupted during a period with little rain. Growth ceased before the end of the wet season, indicating that factors other than moisture availability were limiting. Seeds of Alloteropsis semialata were germinable on production, but did not remain viable or persist on the soil surface through the dry season. Most seeds and young seedlings were harvested and no seedlings were recruited. Inflorescence production increased with plant size. Moderate defoliation in the early wet season had no impact on plant growth, but reduced inflorescence and seed production for at least 2 years. Absence of a seed bank and early wet-season flowering mean that Alloteropsis semialata is likely to be sensitive to long-term over-grazing.

The nature of the perennial response in Mediterranean grasses. I. Water relations and summer survival in Phalaris

1968 ◽  
Vol 19 (3) ◽  
pp. 381 ◽  
Author(s):  
JR McWilliam ◽  
PJ Kramer
Keyword(s):  
Surface Soil ◽  
Perennial Grass ◽  
Soil Surface ◽  
Water Source ◽  
Perennial Grasses ◽  
Natural Conditions ◽  
Deep Roots ◽  
Surface Moisture ◽  
Summer Stress ◽  
Controlled Environments

An important factor in the survival of Phalaris tuberosa, a typical Mediterranean perennial grass, is the ability of its deep root system to supply water during the summer to the dormant culms at the soil surface. This behaviour contrasts with that of the related annual P. minor, which is unable to exploit subsoil moisture, and dies as soon as the surface moisture is exhausted. The volume of water supplied by the perennial roots is sufficient to offset transpiration losses and maintain a favourable water balance in the dormant culms during the summer stress. The importance of this water source for survival is indicated by the death of plants whenever this supply is interrupted by severing deep roots. In field soils under drought conditions roots of the perennial have been followed to a depth of 7 ft in subsoil containing available moisture. The large metaxylem vessels and heavily suberized endodermis which are a feature of these roots suggest that they are well adapted to transport water up through the dry surface soil to the base of the dormant culms. The culms also show typical xerophytic characteristics which help to minimize water loss during the summer, and maintain favourable conditions for the survival of the dormant buds which develop at the basal nodes. These conclusions concerning the survival of the perennial have been drawn from plants growing under natural conditions, and also from more detailed studies under controlled environments. They appear to be of general significance for the perennial grasses adapted to the drier Mediterranean environments and form the basis of the perennial response found in this group.

The Influence of Recent Grazing Pressure and Landscape Position on Grass Recruitment in a Semi-Arid Woodland of Eastern Australia.

1996 ◽  
Vol 18 (1) ◽  
pp. 3 ◽  
Author(s):  
VJ Anderson ◽  
KC Hodgkinson ◽  
AC Grice
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Run Off ◽  
Eastern Australia ◽  
Annual Grasses ◽  
History Of ◽  
Semi Arid

This study examined the effects of previous grazing pressure, position in the landscape and apparent seed trapping capability of soil surface micro-sites on recruitment of the perennial grass Monachather paradoxa (mulga oats) in a semi-arid woodland. Seedling emergence was counted on small plots which had been kept moist for one month. The plots were on bare ground, or at grass tussocks, or at log mounds, sited in the run-off, interception and run-on zones of paddocks that had been grazed for six years at 0.3 and 0.8 sheep equivalent/ha. Few naturally occurring perennial grass seedlings emerged on any of the sites. The level of previous grazing pressure influenced the recruitment of grasses from natural sources as well as from seed of M. paradoxa broadcast on the soil surface; significantly more grass seedlings recruited in paddocks stocked at 0.3 than at 0.8 sheep/ha. Emergence of the sown grass did not differ significantly between the three zones in the landscape, but trends in the data suggest the interception zone may have been the most favourable. Recruitment from in situ grass seed was highest in the mulga grove (run-on) zone. Most seedlings of the sown grass emerged around the bases of existing perennial grass tussocks, but recruitment of volunteer perennial and annual grasses was more evenly distributed between the mulga log-mounds and perennial grass tussocks. It is concluded that very low levels of readily germinable seed of perennial grasses remained in the soil at the end of the drought and that areas with a history of high grazing pressure have less probability of grass recruitment when suitable rain occurs.

Effects of depth and time of sowing and over-wintering on tropical perennial grass seedling emergence in northern New South Wales

2009 ◽  
Vol 60 (10) ◽  
pp. 954 ◽  
Author(s):  
G. M. Lodge ◽  
S. Harden
Keyword(s):  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Perennial Grasses ◽  
Sowing Time ◽  
Rhodes Grass ◽  
Factors Affecting ◽  
Nylon Mesh ◽  
South Wales ◽  
Digitaria Eriantha

Two studies were conducted in northern NSW to examine some of the factors affecting the successful emergence of seedlings of five species of tropical perennial grasses [Panicum coloratum var. makarikariense cv. Bambatsi (panic), Digitaria eriantha ssp. eriantha cv. Premier (digit), Chloris gayana cv. Katambora (Rhodes grass), Dichanthium aristatum cv. Floren (bluegrass), and Bothriochloa bladhii ssp. glabra cv. Swann (forest bluegrass)]. The first experiment investigated the effects of depth and time (month) of sowing on tropical perennial grass seedling emergence, while a second series of studies examined the effects of contact of dispersal/sowing units with the soil, particularly over winter, on subsequent seed germination and seedling emergence. No seedling emergence of any species occurred in September 2006 and June–August 2007. From October 2006 to May 2007 there were significant effects (P < 0.001) of species, sowing time, depth, and their interaction on predicted emergence. From December to March, predicted emergence was always lower for surface-sown caryopses compared with those sown at 10 and 25 mm depth, and Bambatsi was the only species that had >50% emergence from a depth of 50 mm. Recovery of intact caryopses from 300 μm nylon mesh bags stored in the soil for 6 and 12 months was low for all species. Similarly, predicted germination of caryopses from field soil surface and buried locations (2007 and 2008) and those from florets and coated seeds (2008) was low, indicating that these species had a poor ability to over-winter in moist soil.

Establishment of introduced grasses at different stages of pasture development: effects of seedbed

1981 ◽  
Vol 21 (111) ◽  
pp. 417 ◽  
Author(s):  
JG McIvor ◽  
CJ Gardener
Keyword(s):  
Plant Competition ◽  
Thick Layer ◽  
Soil Surface ◽  
Perennial Grasses ◽  
Wet Season ◽  
Stylosanthes Hamata ◽  
Native Grassland ◽  
Successful Establishment ◽  
Chloris Gayana ◽  
Seedbed Preparation

The seedbed preparation necessary for the successful establishment of five promising perennial grasses for the dry tropics was studied on two pastures - native grassland and a pasture dominated by Stylosanthes hamata cv. Verano - near Townsville, in northern Queensland. Seed of Cenchrus ciliaris cv. Biloela, Chloris gayana cv. Callide, Chrysopogon sp. CPI 5221 3, Digitaria milanjiana CPI 5981 4 and Urochloa mosambicensis CPI 46876 was sown into the two pastures, which had been left untreated, sprayed with herbicide, burnt, or burnt and cultivated. S. hamata cv. Verano was also sown on the native grassland plots. Sowings were made at the start of the growing season in successive years. Germination of all lines was adequate except where a thick layer of green and dead herbage physically separated the seed from the soil surface; this happened on the native pasture plots that were untreated or herbicide treated. However, there was high plant mortality in the first month after sowing except where plant competition had been reduced or removed by cultivation or spraying. After this period, most plants survived to the end of the wet season in both pasture types. This pattern of change in plant numbers resulted in good establishment on the cultivated seedbeds, some establishment on the herbicide-treated plots and little or no establishment on the control and burnt plots. Of the five grasses, U. mosambicensis had the best establishment and Chrysopogon sp. and D. milanjiana the worst. None seem likely to survive when sown into living grassland. We therefore conclude that the use of these introduced species will be largely restricted to completely cleared and cultivated land.

Selection of perennial grasses as a component of legume-based pastures on light-textured soils in the dry tropics of Queensland

1994 ◽  
Vol 34 (3) ◽  
pp. 355 ◽  
Author(s):  
TJ Hall ◽  
RW Walker
Keyword(s):  
Native Species ◽  
Perennial Grass ◽  
Genetic Material ◽  
Grazing Pressure ◽  
Perennial Grasses ◽  
Wet Season ◽  
Environmental Evaluation ◽  
Seasonally Dry ◽  
Dry Tropics ◽  
Andropogon Gayanus

Adaptation indices for introduced perennial grasses were derived for a site in the seasonally dry tropics of North Queensland to determine the suitability of grasses as a component of sown legume pastures. Grasses are required to replace native species that are intolerant of the heavy grazing pressure imposed on these legume-based pastures. Agronomic, production, morphological, and reproductive data on 143 accessions of 20 perennial grass genera were compared from 1983 to 1987. The grasses were grown in rows in a grazed Seca and Verano stylo pasture. The seed production potential of 40 Digitaria accessions grown in swards under irrigation was also assessed. The stoloniferous species Bothriochloa pertusa, Digitaria milanjiana, D. taatalensis, B. insculpta, and Urochloa mosamhicensis had the highest adaptation indices under continuous grazing. Digitaria accessions with the ability to produce appreciable viable seed were identified. Andropogon gayanus, a tussock species, had the highest yield and most spread in the first 2 years in the absence of wet season grazing. The potential of B. pertusa and D. milanjiana for stabilising legume pastures has been identified, and the need for wet season grazing management of tussock species has been shown. The range of genetic material in D. milanjiana requires further environmental evaluation.

Tillage practices and the growth and yield of wheat in southern New South Wales: Lockhart, in a 450 mm rainfall region

1986 ◽  
Vol 26 (4) ◽  
pp. 457 ◽  
Author(s):  
IB Mason ◽  
RA Fischer
Keyword(s):  
Plant Growth ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Soil Disturbance ◽  
Growth And Yield ◽  
Wheat Crop ◽  
Severe Drought ◽  
Wet Season ◽  
Tillage Practices ◽  
Direct Drilling

Effects of tillage treatments on the wheat crop were compared during a 3-year cropping phase on a red-brown earth which had previously supported subterranean clover. Direct-drilled wheat after long and short herbicide fallows yielded as well as wheat after cultivated fallow, and differed only in terms of small reductions (averaging 12%) in early plant growth. Non-fallow direct-drill crops had, compared with fallow crops, significantly less soil water (34 mm) and mineral nitrogen (30 kg/ha) at sowing in the first season, but not in later ones. However, they always showed reduced early plant growth, averaging 28% less than cultivated crops, and despite a subsequent narrowing of relative differences in growth gave significantly lower (15%) grain yields in the two wetter seasons; only in the second year, a severe drought causing very low yields, did they produce yields equal to those of fallow plots. The use of narrow combine points in direct drilling, giving incomplete soil disturbance, gave yields equal to those obtained with standard points and complete disturbance of the soil surface. However direct drilling with retained stubble - gave lower yields in a wet season. Averaged over 3 seasons, cultivated fallow yielded 2.54 t/ha, herbicide fallow 2.41 t/ha and non-fallow direct drill with stubble burning 2.17 t/ha. It was concluded that non-fallow direct-drill yields suffered because of reduced presowing water storage and reduced early growth, the latter effect was of less final consequence when the spring was dry.

Silvertop in perennial grass seed production: Effects of type and timing of biotic stresses

2021 ◽  
Author(s):  
Julie Soroka ◽  
Bruce D. Gossen
Keyword(s):  
Seed Production ◽  
Poa Pratensis ◽  
Perennial Grass ◽  
Kentucky Bluegrass ◽  
Development Stage ◽  
Perennial Grasses ◽  
Grass Species ◽  
Biotic Stresses ◽  
Seed Harvest ◽  
Bromus Riparius

Seed production of perennial grasses is an important industry in Canada, but many fields exhibit high proportions of sterile heads with characteristic symptoms in a condition known as silvertop. In a 3-yr field study, biotic stress treatments were applied to caged plots of Kentucky bluegrass (<i>Poa pratensis</i>) and meadow bromegrass (<i>Bromus riparius</i>) to assess their effects on silvertop incidence. Treatments were: 1) control, 2) addition of grass-feeding insects, primarily grass plant bugs (Miridae), 3) inoculation with <i>Fusarium poae</i> spores, 4) both insects and spores, and in one year, 5) mechanical piercing of seed heads above the last node. Additionally, cores of the two grass species were potted and removed from the field in spring in each of 2 years. After 2-, 4-, and 6-wk intervals in a cold room at 4° C to stagger plant development stage, the five treatments were applied to caged plants of both grasses, which were maintained in a greenhouse until seed harvest. In both studies, the numbers of healthy seed heads, percentage of heads with silvertop, and seed weights were determined. In the field, stress treatments infrequently and inconsistently affected silvertop levels. Regression showed that the relationship between silvertop and seed yield, although significant, explained little of the variability in yield. Silvertop developed in all treatments in the greenhouse; treatments had no effect on silvertop levels, which were highest in plants treated at the R1 (boot) growth stage. This suggests that the boot stage of the two grass species is most vulnerable to silvertop occurrence.

scholarly journals Effects of Simulated Herbivory on the Vegetative Reproduction and Compensatory Growth of Hordeum brevisubulatum at Different Ontogenic Stages

2019 ◽  
Vol 16 (9) ◽  
pp. 1663 ◽  
Author(s):  
Jihong Yuan ◽  
Ping Wang ◽  
Yunfei Yang
Keyword(s):  
Plant Growth ◽  
Primary Production ◽  
Aboveground Biomass ◽  
Compensatory Growth ◽  
Vegetative Reproduction ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Ecological Research ◽  
Simulated Herbivory ◽  
Hordeum Brevisubulatum

The response of plant vegetative reproduction and compensatory growth to herbivory has been widely discussed in biological and ecological research. Most previous research has supported the idea that both vegetative reproduction and compensatory growth are affected by their ontogenic stage. However, in many studies, the effects of foraging at different ontogenic stages was often confounded with the effects of foraging at different phenological periods for perennials. Our experiment was conducted in a natural meadow with a perennial grass, Hordeum brevisubulatum, and four ontogenic stages were chosen as our experimental objects. Three different clipping intensities during three phenological periods were implemented to explore the effects of simulating animal foraging on vegetative reproduction and compensatory plant growth. The results indicated that there were significant effects of ontogenic stage, phenological period, and clipping intensity on vegetative reproduction and compensatory growth. Moderate clipping intensities significantly increased the number of vegetative tillers, the total number of juvenile tillers and buds, and the aboveground biomass at early phenological periods for individuals at early ontogenic stages. Our results suggested that moderate clipping intensities could induce only an over-compensation response in perennial grasses at both the early ontogenic stage and phenological period, and the ability of compensatory growth gradually decreased with the progression of the ontogenic stage. This is of great significance to the primary production of grasslands subjected to herbivory.

Long-term effect of pastures on soil quality in acid soil of North-East India

Soil Research ◽  
2009 ◽  
Vol 47 (4) ◽  
pp. 372 ◽  
Author(s):  
P. K. Ghosh ◽  
R. Saha ◽  
J. J. Gupta ◽  
T. Ramesh ◽  
Anup Das ◽  
...  
Keyword(s):  
Soil Water ◽  
Soil Quality ◽  
Microbial Biomass Carbon ◽  
Acid Soil ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Pennisetum Purpureum ◽  
North East India ◽  
North East

North-East India is known for its complex, diverse, risk-prone, and fragile hilly ecosystem. Natural resources in terms of soil, water, vegetation, and soil organic carbon (SOC) are much degraded. Effects of long-term perennial grasses maintained at a permanent fodder block of the ICAR Research Complex, Meghalaya, on soil quality were examined after 15 cropping cycles. The aims were (i) to ascertain whether perennial grass primarily maintained as fodder source for ruminants could conserve resources and improve soil quality in the hilly ecosystem of North-East India, and (ii) to select a suitable perennial grass to minimise land degradation, restore SOC, and improve the soil quality. Soil samples were collected in 2007–08 (dry season) from plots of 8 perennial grasses [Setaria sphacelata (setaria), Brachieria rosenesis (congosignal), Thysanolaena maxima (broom), Penicum maximum var. Makunia and var. Hamil (guinea), Pennisetum purpureum (napier), Paspalum conjugalum (paspalam), Arachis pintoi (wild groundnut)] and analysed for physical, chemical, and biological properties. A control plot had no grass cover. Hamil and Makunia produced a large amount of green fodder, while Makunia, paspalam, setaria, and congosignal had greatest root biomass. Relative to the control, soil under perennial grasses showed increases of ~30% SOC, 70% mean weight diameter, 20% available soil water, 40% hydraulic conductivity, 63% infiltration rate, and 10% soil microbial biomass carbon. Among grasses, soil under setaria, congosignal, and Makunia had higher values of these attributes than under other species because of better soil binding through an extensive root system. Improvement of soil physical properties and processes under these grasses, coupled with complete ground cover, reduced soil erosion by ~33% and also signified ecological benefits through C-sequestration. Soil quality management in the fragile ecosystem of North-East India should include permanent pastural grasses, particularly, setaria, congosignal, and Makunia.

Propoxycarbazone-Sodium and Imazapic Effects on Downy Brome (Bromus tectorum) and Newly Seeded Perennial Grasses

2011 ◽  
Vol 4 (1) ◽  
pp. 78-86 ◽  
Author(s):  
Gustavo M. Sbatella ◽  
Robert G. Wilson ◽  
Stephen F. Enloe ◽  
Charlie Hicks
Keyword(s):  
Plant Biomass ◽  
Perennial Grass ◽  
Perennial Grasses ◽  
Grass Species ◽  
Downy Brome ◽  
Intermediate Wheatgrass ◽  
Psathyrostachys Juncea ◽  
Annual Grasses ◽  
Russian Wildrye

AbstractVigorous stands of perennial grasses can effectively provide long-term control of many invasive plants on rangelands. However, in degraded conditions, successful reestablishment of perennial grasses can be compromised by invasive annual grasses, such as downy brome. Propoxycarbazone-sodium is a selective herbicide currently labeled for downy brome control in small grains, but its potential use on rangelands is unknown. Studies were conducted from 2004 through 2008 at three rangeland sites in Colorado and Nebraska to evaluate downy brome control and perennial grass injury with propoxycarbazone-sodium and imazapic. Propoxycarbazone-sodium provided satisfactory downy brome control with grass injury equal to or less than imazapic when rainfall followed the fall application. A second set of studies was conducted from 2007 to 2008 at Lingle, WY, and Scottsbluff, NE, to determine the plant-back interval and postemergence application response of seven perennial grass species to propoxycarbazone-sodium and imazapic. Grass tolerance to both herbicides was good when applied 90 and 120 d before planting (DBP). However, grass injury increased as plant-back interval decreased. The greatest impact on plant biomass was observed from herbicide applied at planting or after planting. Crested and intermediate wheatgrass (Agropyron cristatumandThinopyrum intermedium) biomass production was not affected when herbicides were applied 90 or 120 DBP. Western wheatgrass (Pascopyrum smithii) and Russian wildrye (Psathyrostachys juncea) showed tolerance to imazapic applied before planting. Smooth brome (Bromus inermis), sheep fescue (Festuca ovina), and orchardgrass (Dactylis glomerata) showed the least amount of tolerance to propoxycarbazone-sodium and imazapic.

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