An awn typology for Australian native grasses (Poaceae)

2019 ◽  
Vol 67 (4) ◽  
pp. 309 ◽  
Author(s):  
Annette M. Cavanagh ◽  
Robert C. Godfree ◽  
John W. Morgan
Keyword(s):  
Potential Function ◽  
Morphological Variation ◽  
Classification System ◽  
Grass Species ◽  
Native Grasses ◽  
Ecological Role ◽  
Native Grass ◽  
C4 Species ◽  
C3 Species

Australia has a large diversity of native grasses. The diaspores of many species possess awns that vary considerably in their number and shape. Some variations of awn shape have been found to be effective at diaspore dispersal. Although morphological descriptions of awns exist for most native grass species, the number of species that possess awns and the extent of awn variation is unknown. This makes it difficult to determine the evolutionary importance of awns and the potential function of the various morphologies. The aim of this study was to construct an awn typology based on morphological descriptions collated from published flora databases that will quantify the awn type diversity of all native grass species in Australia, and will inform awn type relationships and help to clarify the role of differing awn morphologies in diaspore dispersal. We found that 42.1% of 1000 Australian native grasses with a single awn type were determined to have a ‘significant’ awn. These could be classified into one of 20 awn types, the most common being (1) single, apical, geniculate (once-sharply bent) awns (93 species; 28 genera, especially Iseilema), (2) three, apically-attached, straight awns (59 species, mainly Aristida) and (3) single, apical, bigeniculate (twice-sharply bent) awns (46 species, mainly Austrostipa). Among Australian grasses, slightly (though significantly) more C3 species (49.2%) had awns than C4 species (39.9%), although the most common awn types in both contained sharply bent awns (bigeniculate and geniculate respectively). Our classification system will help to improve our understanding of the amount of awn morphological variation in Australian grasses and will enable further investigation into the important ecological role of awns in species fitness.

Smoke affects the Germination of Native Grasses of New South Wales

1999 ◽  
Vol 47 (4) ◽  
pp. 563 ◽  
Author(s):  
Tamara R. Read ◽  
Sean M. Bellairs
Keyword(s):  
New South ◽  
Germination Rate ◽  
New South Wales ◽  
Germination Percentage ◽  
Grass Species ◽  
Native Grasses ◽  
Environmental Stimulus ◽  
Native Grass ◽  
South Wales ◽  
Stimulation Of

The germination responses to plant-derived smoke of seeds of 20 native grass species from New South Wales, Australia, were tested under laboratory conditions. The species belonged to 14 genera including Bothriochloa, Chloris, Cymbopogon, Danthonia, Dichanthium, Digitaria, Eragrostis, Eriochloa, Microlaena, Panicum, Paspalidium, Poa, Stipa and Themeda. The interaction between smoke and husk-imposed dormancy was examined by removing the floral structures surrounding the seeds, when sufficient seeds were available. Smoke was shown to be an important environmental stimulus for breaking the dormancy of native grasses; however, the response differed considerably between different genera and between species of the same genus. For almost half of the species, smoke significantly increased the germination percentage. Panicum decompositum showed the greatest response, with germination increasing from 7.7 to 63.1% when smoke was applied. Panicum effusum had no germination in the absence of smoke, but 16.7% germination when smoke was applied. Stipa scabra subsp. scabra had germination significantly reduced by smoke from 30.2 to 19.9%. Five species had their germination rate, but not the final germination percentage, affected by smoke, and a third of the species were unaffected by smoke. For five of the species, Chloris ventricosa, Dichanthium sericeum, Panicum decompositum, Poa labillardieri and Stipa scabra subsp. falcata, this is the first report of a smoke-stimulated germination response. For those species with germination promoted by smoke, retention of the covering structures did not prevent smoke stimulation of germination. Sowing smoke-treated husked seeds is likely to be preferable as it would still promote greater germination, whereas dehusking seeds can result in the seeds being more susceptible to desiccation and fungal attack in the field. It is suggested that other grassland communities that respond to pyric conditions may also contain species that respond to smoke.

scholarly journals Phosphorus fertiliser management for pastures based on native grasses in south-eastern Australia

2019 ◽  
Vol 70 (12) ◽  
pp. 1044
Author(s):  
M. L. Mitchell ◽  
M. R. McCaskill ◽  
R. D. Armstrong
Keyword(s):  
Low Fertility ◽  
Grass Species ◽  
Soil Test ◽  
Native Grasses ◽  
Native Grass ◽  
Themeda Triandra ◽  
South Eastern ◽  
Eastern Australia ◽  
Native Pasture ◽  
South Eastern Australia

Approximately 3.1 Mha (22%) of the agricultural area of south-eastern Australia can be classified as native pasture. There is the assumption that, owing to the widespread occurrence of low-fertility soils in Australia, native grass species do not respond to increased phosphorus (P) fertility. Currently, there are no industry recommendations of target soil-test P values for native-grass-based pastures. This paper reviews the responses of perennial native pasture species endemic to south-eastern Australia to P application in controlled environments, surveys, replicated experiments and paired-paddock trials. Eighty-seven site-years of trial data where different levels of P were applied, conducted over the last two decades, on native-based pastures in south-eastern Australia are reviewed. Data indicate that application of P fertilisers to native grass pastures can increase dry matter (DM) production and maintain pasture stability. However, minimum targets for herbage mass (800 kg DM/ha) and groundcover (80%) are required to ensure persistence of perennial native grasses. Stocking rates also need to match carrying capacity of the pasture. Based on previous research, we recommend target soil-test (Olsen; 0–10 cm) P levels for fertility-tolerant native grass pastures, based on Microlaena stipoides, Rytidosperma caespitosum, R. fulvum, R. richardsonii, R. duttonianum and R. racemosum, of 10–13 mg/kg, whereas for pastures based on fertility-intolerant species such as Themeda triandra, lower levels of <6 mg/kg are required to ensure botanical stability.

Germination of selected Australian native grass species, with potential for minesite rehabilitation

2013 ◽  
Vol 61 (4) ◽  
pp. 283 ◽  
Author(s):  
Grus J. Farley ◽  
Sean M. Bellairs ◽  
Stephen W. Adkins
Keyword(s):  
Seed Dormancy ◽  
Seed Coat ◽  
Seed Viability ◽  
Grass Species ◽  
Native Grasses ◽  
Native Grass ◽  
The Past ◽  
Dispersal Unit ◽  
Seed Fill ◽  
Filled Seeds

Native grasses have become increasingly important in the post-mining landscape where land rehabilitators try to reconstruct vegetation communities similar to those present before land clearing. So as to include native grasses in these communities, there is a requirement to understand their germination biology, because in the past, many grasses have typically been hard to establish in the final community. The present study found that poor germination of 13 native grass species was due to (1) low percentage of seed fill, (2) low seed viability of filled seeds and/or (3) seed dormancy. Eight species had dormancy treatments investigated. Most were found to exhibit at least one form of dormancy that was either located in the hull structures immediately external to the caryopsis (i.e. the lemma, palea and glumes), within the seed coat (i.e. testa and pericarp, tissues that are found inside the hull, but external to the embryo and endosperm) and/or within the embryo. Seven of the grass species tested were found to have a dormancy mechanism present in two or more locations of their dispersal unit. Germination of the selected native grass species could be improved by (1) processing seeds to enrich the percentage of seeds that are filled, (2) testing viability to ensure a high proportion of the seeds are likely to germinate or (3) using methods to help overcome dormancy and promote germination.

Ultrastructural Changes in Root Cap Cells of Two Australian Native Grass Species Following Exposure to Aluminium

1997 ◽  
Vol 24 (2) ◽  
pp. 165 ◽  
Author(s):  
Simon A. Crawford ◽  
Sabine Wilkens
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Root Cap ◽  
Ultrastructural Changes ◽  
Grass Species ◽  
Aluminium Tolerance ◽  
Secretory Vesicles ◽  
Native Grass ◽  
Transmission Electron

Transmission electron microscopy was used to investigate ultrastructural changes in root cap cells of two aluminium-tolerant native grass species, Danthonia linkii Kunth and Microlaena stipoides (Labill.) R.Br., following exposure to Al. Quantitative differences in root cap cells and organelles in response to 0–10 ppm aluminium were determined using image analysis of electron micrographs. Changes to the size of root cap cells due to exposure to Al were similar in the two species with a low Al concentration (1–2 ppm) resulting in larger cells, while higher Al levels (5–10 ppm) reduced cell size. In peripheral cap cells of the more Al-tolerant M. stipoides, the size of secretory vesicles was not affected by exposure to Al, while in peripheral cap cells of the less Al-tolerant D. linkii, exposure to Al resulted in significantly smaller secretory vesicles being produced. Central root cap cells from control plants of M. stipoides contained 90% more dictyosomes and had 50% larger amyloplasts than D. linkii. Measurement of mucilage droplets showed that roots of M. stipoides produced much more mucilage than D. linkii. Exposure of roots of M. stipoides to Al in the range 2–10 ppm had no effect on the size of mucilage droplets produced. The possible role of mucilage production in aluminium tolerance is discussed.

Ecological role of pyrolysis by-products in seed germination of grass species

2017 ◽  
Vol 108 ◽  
pp. 78-82 ◽  
Author(s):  
Linjun Yao ◽  
M. Anne Naeth ◽  
Federico P.O. Mollard
Keyword(s):  
Seed Germination ◽  
Grass Species ◽  
Ecological Role ◽  
By Products

A survey of farms on the Central, Southern and Monaro Tablelands of New South Wales: management practices, farmer knowledge of native grasses, and extent of native grass areas

2000 ◽  
Vol 40 (8) ◽  
pp. 1081 ◽  
Author(s):  
D. L. Garden ◽  
P. M. Dowling ◽  
D. A. Eddy ◽  
H. I. Nicol
Keyword(s):  
Management Practices ◽  
New South ◽  
New South Wales ◽  
Perennial Grasses ◽  
Grass Species ◽  
Large Contribution ◽  
Native Grasses ◽  
Pasture Production ◽  
Native Grass ◽  
South Wales

Results are presented of a survey of pastoral properties on the Central, Southern and Monaro Tablelands of New South Wales carried out during 1991—92. Landholders were interviewed to obtain information on property size, enterprise types, grazing management, tree clearing, fertiliser history and carrying capacity. In addition, familiarity with native grass species, and knowledge of their value were determined. The main grazing enterprises were wool and beef. The most common form of livestock management was continuous grazing. Most properties had been extensively cleared of trees (average cleared area 80%), and there had been a significant amount of disturbance of the original pastures. This varied from 40% of total property area for the Central and Monaro Tablelands to 60% for the Southern Tablelands. The main form of disturbance was cultivation for pasture sowing or fodder cropping. Landholders had used 80% more fertiliser on disturbed areas than on undisturbed areas, with most fertiliser applied on the Southern Tablelands and least on the Monaro Tablelands. The average carrying capacities of undisturbed and disturbed pastures over the tablelands were 4.3 and 7.7 dry sheep equivalents per hectare, respectively. While most landholders were satisfied with the performance of their sown pastures, there was a lack of knowledge of the contribution of native perennial grasses to pasture production. Using survey data, it was estimated that pastures with native grasses as the major components covered a minimum of 1.38 million hectares or 40% of the surveyed area. With such a large contribution to production, there is a need to assist landholders to identify native perennial grasses so that their potential value can be more fully realised.

Effect of Carbonic Anhydrase Inhibition on Photosynthesis by Leaf Pieces of C3 and C4 Plants

1995 ◽  
Vol 22 (1) ◽  
pp. 45 ◽  
Author(s):  
MR Badger ◽  
H Pfanz
Keyword(s):  
Carbonic Anhydrase ◽  
Inorganic Carbon ◽  
C4 Plants ◽  
C3 And C4 Plants ◽  
Pep Carboxylase ◽  
Nicotiana Rustica ◽  
C4 Species ◽  
Spinacea Oleracea ◽  
C3 Species

The role of carbonic anhydrase (CA) in the photosynthesis of C3 and C4 plants was investigated by use of the effects of the CA inhibitor ethoxyzolamide on peeled and vacuum infiltrated leaf pieces. Two C4(Zea mays and Amaranthus edulis) and three C3 (Spinacea oleracea, Nicotiana rustica and Hordeum vulgare) species were studied. The results clearly showed that photosynthesis at limiting inorganic carbon was more severely inhibited in the C4 species compared with the C3 species. However, the degree of inhibition in the C4 species was less than might have been expected based on the rate limitation which the conversion of CO2 to HCO3- would impose on the provision of substrate to PEP carboxylase. The reasons for this lower than expected inhibition is discussed in terms of the lack of penetration of ethoxyzolamide, the diffusion of HCO3- through plasmodesmata and the possible existence of a plasma membrane CA activity.

Ecological Role of Exopolysaccharides of Bacillariophyta: A Review

2017 ◽  
Vol 19 (1) ◽  
pp. 5-24 ◽  
Author(s):  
E. I. Shnyukova ◽  
E. K. Zolotareva
Keyword(s):  
Ecological Role
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