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.

Temperatures for seedling emergence of tropical perennial grasses

2017 ◽  
Vol 68 (5) ◽  
pp. 493
Author(s):  
M. K. Egan ◽  
S. P. Boschma ◽  
S. Harden ◽  
C. A. Harris ◽  
C. Edwards
Keyword(s):  
Seedling Emergence ◽  
Perennial Grasses ◽  
Sowing Time ◽  
Rhodes Grass ◽  
Temperature Range ◽  
South Wales ◽  
Optimal Temperature Range ◽  
Digitaria Eriantha ◽  
Chloris Gayana ◽  
Rainfall Region

A growth-cabinet study was conducted to determine the optimum temperature range for seedling emergence of seven tropical grasses commonly sown in the frost-prone, summer-dominant rainfall region of inland northern New South Wales. The grasses were Bothriochloa bladhii subsp. glabra (forest bluegrass) cv. Swann, Bothriochloa insculpta (creeping bluegrass) cv. Bisset, Chloris gayana (Rhodes grass) cv. Katambora, Digitaria eriantha (digit grass) cv. Premier, Panicum coloratum var. makarikariense (makarikari grass) cv. Bambatsi, and Megathyrsus maximus (panic) cvv. Gatton and Megamax 059. Six constant temperatures were used, ranging from 10°C to 35°C in 5°C increments. Katambora Rhodes grass was the only grass to emerge at 10°C; seedlings of all grasses emerged at temperatures >10°C. Optimal temperature range for emergence varied between species, falling into three groups: low (Bisset creeping bluegrass 16−22°C); intermediate (Premier digit grass 21−32°C, Swann forest bluegrass 23−31°C, Megamax 059 panic 23−35°C, Gatton panic 24−32°C); and high (Bambatsi makarikari grass 24−35°C, Katambora Rhodes grass 24−35°C). The temperature range at which 50% of optimum emergence occurred was 12−14°C for Katambora Rhodes grass, Bisset creeping blue and Premier digit, and 17−18°C for the panic grasses, Swann forest bluegrass and Bambatsi makarikari grass. These temperatures provide options for sowing earlier in spring or later in summer–autumn and may assist development of sowing time options in new environments and provide insight into competition between species.

Effects of depth and time of sowing on emergence of Danthonia richardsonii Cashmore and Danthonia linkii Kunth

1993 ◽  
Vol 44 (6) ◽  
pp. 1311 ◽  
Author(s):  
GM Lodge ◽  
AJ Schipp
Keyword(s):  
New South ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Maximum Temperature ◽  
Sowing Time ◽  
Sand Mixture ◽  
South Wales ◽  
Seed Field ◽  
Dry Conditions ◽  
Soil Temperatures

Two experiments examined the effects of sowing time and depth (surface and 10, 25, 50 mm) on emergence of Danthonia richardsonii Cashmore and Danthonia linkii Kunth. Experiment 1 was conducted from January to December 1990 on a loam/sand mixture in boxes. Emergence was highest in both species for seeds sown onto the soil surface in summer and autumn (P < 0.05). Sowing at any depth at any time of the year, or surface sowing in winter and spring, markedly reduced emergence. Experiment 2 was conducted in the field at Tamworth, northern New South Wales from September 1991 to August 1992, on a red brown earth and a black earth. This study confirmed that emergence in both species was highest from surface sown seed. Field emergence was lowest in winter, but in contrast to experiment 1, it was higher in spring, particularly on the black earth. Seedling emergence appeared to be related to mean maximum temperature, decreasing in winter as it declined below 20�C, and increasing in spring when it was greater than 23�C. Differences in seed weight were reflected in emergence of D. richardsonii and D. linkii in experiment 1. Similar emergence was recorded for the loamlsand mixture and sand, indicating that there was little effect of texture. Phalaris aquatica L. cv. Sirosa surface sown in December had lower emergence ( P < 0.05) than both Danthonia spp., but emergence of this larger seeded cultivar was higher at depths of 10 and 25 mm. Laboratory studies to determine reasons for the low emergence of D. richardsonii and D. linkii from depth, indicated that neither had an obligate light requirement for germination. Depth, however, reduced germination (P < 0.05) compared with surface sowing of seed. Seedlings at depth also were observed to have slower rates of shoot and root elongation. In the field, the most successful establishments of D. richardsonii and D. linkii seedlings are likely to occur from surface sowings in April and May. Sowing in spring may also be possible if mean maximum soil temperatures exceed 23�C, and seedlings can establish before the onset of hot, dry conditions in summer.

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.

Replacement series studies of competition between tropical perennial and annual grasses and perennial grass mixtures in northern New South Wales

2009 ◽  
Vol 60 (6) ◽  
pp. 526 ◽  
Author(s):  
G. M. Lodge ◽  
S. P. Boschma ◽  
S. Harden
Keyword(s):  
Perennial Grass ◽  
Maximum Likelihood Estimates ◽  
Separate Experiment ◽  
Replacement Series ◽  
Rhodes Grass ◽  
Barnyard Grass ◽  
Tropical Grasses ◽  
South Wales ◽  
Digitaria Eriantha ◽  
Annual Grasses

Seedlings of three perennial tropical grasses, Chloris gayana cv. Katambora (Rhodes grass), Panicum coloratum var. makarikariense cv. Bambatsi (panic grass), and Digitaria eriantha ssp. eriantha cv. Premier (digit grass), were each grown in replacement series mixtures with seedlings of the annual summer-growing grass weeds Urochloa panicoides (liverseed grass) and Echinochloa colona (awnless barnyard grass). A separate experiment examined the competitiveness of seedlings of the three perennial tropical grasses when two species were sown together. Plants were sown 50 mm apart in boxes at a density of 307 plants/m2. Maximum likelihood estimates were used to derive parameters of a non-linear competition model using the dry weights of perennial and annual grasses. Seedlings of the summer-growing annual liverseed grass competed aggressively with those of the tropical perennial Katambora Rhodes grass. However, Bambatsi panic seedlings were equally competitive with those of awnless barnyard grass, while those in a Premier digit-barnyard grass mixture were inhibited by the presence of each other. In the perennial grass mixtures study, the performance of both Premier digit and Bambatsi panic was adversely affected by the presence of Katambora Rhodes grass.

Satellite derived maps of pasture growth status: association of classification with botanical composition

1997 ◽  
Vol 37 (5) ◽  
pp. 547 ◽  
Author(s):  
P. J. Vickery ◽  
M. J. Hill ◽  
G. E. Donald
Keyword(s):  
Near Infrared ◽  
Perennial Grass ◽  
Vegetation Indices ◽  
Fast Growth ◽  
Perennial Grasses ◽  
Bayesian Probability ◽  
Cumulative Probability ◽  
Botanical Composition ◽  
South Wales ◽  
Native Pastures

Summary. Spectral data from the green, red and near-infrared bands of Landsat MSS and Landsat TM satellite imagery acquired in mid-spring were classified into 3 and 6 pasture growth classes respectively. The classifications were compared with a site database of botanical composition for the Northern Tablelands of New South Wales to examine the association between spectral growth class and pasture composition. Pastures ranged in composition from unimproved native perennial grasses through semi-improved mixtures of native and naturalised grasses and legumes to highly improved temperate perennial grasses and legumes. For 3 years of MSS data, the fast growth class had a mean botanical composition of about 80% improved perennial grass and 0% native; medium growth class averaged 46% improved perennial grass and 14% native; while the slow growth class had about 60% native and 1% improved perennial grass when averaged over 3 years of MSS data. For the 6 class TM data from a single year, a predictive logistic regression of cumulative probability was developed for percentage of ‘very fast’ growth pixels and ordered 10 percentile categories of improved perennial grass or native grass. Differences in patch characteristics between classes with MSS disappeared with TM reclassified to the same 3 class level. Most probable pasture type was inferred from 3 class MSS and TM data using Bayesian probability analysis. The resulting maps were similar in general appearance but detail was better with the TM data. The pasture growth classification identified highly improved perennial grass pastures and native pastures but sensitivity to intermediate pasture types was poor. Future improvement will come from direct measurement of biophysical characteristics using vegetation indices or inversion of reflectance models.

scholarly journals Factors affecting Cyperus difformis seed germination and seedling emergence

2013 ◽  
Vol 31 (4) ◽  
pp. 823-832 ◽  
Author(s):  
A. Derakhshan ◽  
J. Gherekhloo
Keyword(s):  
Seed Germination ◽  
Integrated Management ◽  
Germination Rate ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Soil Surface ◽  
Weed Species ◽  
Factors Affecting ◽  
Cyperus Difformis ◽  
Emergence Patterns

Specific knowledge about the dormancy, germination, and emergence patterns of weed species aids the development of integrated management strategies. Laboratory studies were conducted to determine the effect of several environmental factors on seed germination and seedling emergence of Cyperus difformis. Germination of freshly harvested seeds was inhibited by darkness; however, when seeds were subsequently transferred to complete light they germinated readily. Our results showed that 2 wk of cold stratification overcome the light requirement for germination. Seeds of C. difformis were able to germinate over a broad range of temperatures (25/15, 30/20, 35/25, and 40/30 ºC day/night). The response of germination rate to temperature was described as a non-linear function. Based on model outputs, the base, the optimum and the ceiling temperatures were estimated as 14.81, 37.72 and 45 ºC, respectively. A temperature of 120 ºC for a 5 min was required to inhibit 50% of maximum germination. The osmotic potential and salinity required for 50% inhibition of maximum germination were -0.47 MPa and 135.57 mM, respectively. High percentage of seed germination (89%) was observed at pH=6 and decreased to 12% at alkaline medium (pH 9) pH. Seeds sown on the soil surface gave the greatest percentage of seedling emergence, and no seedlings emerged from seeds buried in soil at depths of 1 cm.

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.

Soil seals in tropical tall grass pastures of northern Australia

Soil Research ◽  
1979 ◽  
Vol 17 (3) ◽  
pp. 483 ◽  
Author(s):  
J Mott ◽  
BJ Bridge ◽  
W Arndt
Keyword(s):  
Surface Soil ◽  
Seedling Emergence ◽  
Perennial Grass ◽  
Soil Surface ◽  
Mechanical Impedance ◽  
Organic Carbon Content ◽  
Grass Cover ◽  
Northern Australia ◽  
Tall Grass ◽  
Pastoral Management

Stable bare degraded areas exist in the lightly grazed perennial grass understorey existing in the eucalypt woodlands of northern Australia. Examination of these areas showed large differences in infiltration which led to increased runoff from the bare sites. However, there was little difference in soil composition between grass-covered and degraded sites apart from a higher organic carbon content in surface soil under grass. Micromorphological examination showed that soil without grass cover had lost its original open structure in the surface layers, developing a surface seal. The surface soil of the bare sealed area was shown to slake readily under quick wetting in contrast to soil surface under grass cover which did not slake. Heavy grazing of the grass understorey destroyed grass clumps within two wet seasons. Once the clumps were killed the soil surface quickly collapsed to form sealed areas, with the same properties as those occurring in ungrazed sites. The persistence of the bare sealed areas is attributed to seed removal during runoff, high temperatures and low moisture content in the sealed layer, as well as mechanical impedance preventing seedling emergence. As re-establishment of native grasses is difficult in this region, care must be taken in pastoral management to prevent the formation of degraded sites, which may take many years to re-vegetate.

Factors affecting seed germination of annual sowthistle (Sonchus oleraceus) in southern Australia

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 854-860 ◽  
Author(s):  
Bhagirath S. Chauhan ◽  
Gurjeet Gill ◽  
Christopher Preston
Keyword(s):  
Seed Germination ◽  
Osmotic Potential ◽  
Field Experiments ◽  
Soil Depth ◽  
Seedling Emergence ◽  
Soil Surface ◽  
Factors Affecting ◽  
Control Programs ◽  
Buried Seed ◽  
Ph Range

Annual sowthistle has become more abundant under no-till systems in southern Australia. Increased knowledge of germination biology of annual sowthistle would facilitate development of effective weed control programs. The effects of environmental factors on germination and emergence of annual sowthistle seeds were examined in laboratory and field experiments. Seeds of annual sowthistle were able to germinate over a broad range of temperatures (25/15, 20/12, and 15/9 C day/night temperatures). Seed germination was favored by light; however, some germination occurred in the dark as well. Greater than 90% of seeds germinated at a low level of salinity (40 mM NaCl), and some seeds germinated even at 160 mM NaCl (7.5%). Germination decreased from 95% to 11% as osmotic potential increased from 0 to −0.6 MPa and was completely inhibited at osmotic potential greater than −0.6 MPa. Seed germination was greater than 90% over a pH range of 5 to 8, but declined to 77% at pH 10. Seedling emergence was the greatest (77%) for seeds present on the soil surface but declined with depth, and no seedlings emerged from a soil depth of 5 cm. In another experiment in which seeds were after-ripened at different depths in a field, seed decay was greater on the soil surface than at 2 or 5 cm depth. At the end of the growing season, there was a much greater persistence of buried seed (32 to 42%) than seeds present on the soil surface (8%). Greater persistence of buried seed could be due to dormancy enforced by dark in this species.

Factors affecting germination of horseweed (Conyza canadensis)

Weed Science ◽  
2006 ◽  
Vol 54 (5) ◽  
pp. 898-902 ◽  
Author(s):  
Vijay K. Nandula ◽  
Thomas W. Eubank ◽  
Daniel H. Poston ◽  
Clifford H. Koger ◽  
Krishna N. Reddy
Keyword(s):  
Seedling Emergence ◽  
Soil Surface ◽  
Conyza Canadensis ◽  
Light Conditions ◽  
Complete Darkness ◽  
Continuous Darkness ◽  
Factors Affecting ◽  
Nacl Concentration ◽  
Alkaline Conditions ◽  
Ph Range

The influence of environmental factors on germination and emergence of horseweed was examined in growth chamber experiments. Germination was highest (61%) under 24/20 C day/night temperature under light. Horseweed seed germination was observed under both light (13 h photoperiod) and complete darkness (24 h), but germination under continuous darkness was only 0 to 15% compared with 0 to 61% under light. All other experiments were conducted under 24/20 C and 13-h light conditions. Germination was 19 to 36% over a pH range from 4 to 10, with a trend toward higher germination under neutral-to-alkaline conditions. Horseweed germination was > 20% at < 40 mM NaCl concentration and lowest (4%) at 160 mM NaCl. These data suggest that even at high soil salinity conditions, horseweed can germinate. Germination of horseweed decreased from 25% to 2% as osmotic potential increased from 0 (distilled water) to −0.8 MPa, indicating that germination can still occur under moderate water stress conditions. Horseweed seedling emergence was at its maximum on the soil surface, and no seedlings emerged from seeds placed at a depth of 0.5 cm or higher.

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