A Quantitative Study of the Spores and Anatomy of Mycorrhizas Formed by a Species of Glomus, With Reference to Its Taxonomy

1979 ◽  
Vol 27 (4) ◽  
pp. 363 ◽  
Author(s):  
LK Abbott ◽  
AD Robson
Keyword(s):  
Size Range ◽  
Trifolium Subterraneum ◽  
Arbuscular Mycorrhizas ◽  
Nitrogen Supply ◽  
Lolium Rigidum ◽  
Anatomical Characteristics ◽  
Vesicular Arbuscular ◽  
Identification Of Species ◽  
The Relationship ◽  
Erodium Botrys

The development of spores and sporocarps was studied in two isolates of a species of Glomus collected in Western Australia. The isolates, which had been maintained in pot culture, differed slightly in the size range of spores and in the relationship between spore size and the development of the peridium. Anatomical characteristics of mycorrhizas of three pasture species (Trifolium subterraneum, Erodium botrys and Lolium rigidum) formed with this species of Glomus were essentially the same and were largely unaffected by nitrogen supply. The hyphae in nitrogen-deficient plants were slightly wider than those in nitrogen-adequate plants of T. subterraneum and E. botrys. The effect of phosphorus supply on the anatomy of mycorrhizas formed by this fungus and T. subterraneum was studied with time. Phosphorus supply had no effect on the formation of arbuscles, the density of hyphae within infected roots, or the morphology of the branching pattern of the endophyte hyphae within the root. However, phosphate added above that required for maximum plant yield eliminated vesicle formation. Anatomical characteristics of the mycorrhizas changed little with time except for arbuscle number, which decreased markedly between 29 and 50 days after sowing. We concluded that the anatomy of vesicular arbuscular mycorrhizas formed by a particular endophyte species grown under a range of conditions may not be as variable as has been generally assumed. There is scope for identification of species of endophyte within plant roots. Furthermore, some features of infection morphology could prove to be useful for taxonomic purposes.

Nitrogen in temperate crop and pasture plants

1975 ◽  
Vol 26 (1) ◽  
pp. 103 ◽  
Author(s):  
JS Gladstones ◽  
JF Loneragan
Keyword(s):  
Nitrogen Concentration ◽  
Trifolium Subterraneum ◽  
Lolium Rigidum ◽  
High Nitrogen ◽  
Pasture Legumes ◽  
Ornithopus Compressus ◽  
Nitrogen Concentrations ◽  
Three Stages ◽  
Erodium Botrys ◽  
Pasture Plants

Nitrogen concentrations were determined in the tops of 24 annual crop and pasture varieties grown together in ungrazed plots on a lateritic gravelly sand at Gidgegannup, W.A., and sampled at three stages during growth and at maturity. All legumes had higher nitrogen concentrations in the tops than all non-legumes, but considerable variation was evident within each group. Among pasture legumes, Ornithopus compressus and O. sativus had the highest concentrations, especially towards maturity, and Trifolium subterraneum cv. Yarloop and Clare the lowest. Nitrogen concentrations in all Lupinus spp. fell rapidly towards maturity, and they were unique in suffering substantial net nitrogen losses from the tops. The herb Erodium botrys grew better and took up more nitrogen under conditions of deficiency than did the grasses. Its nitrogen concentration was nevertheless very low. Among the grasses, Bromus rigidus consistently had the highest nitrogen concentration and Lolium rigidum the lowest. There was some evidence among non-legumes of a correlation between high nitrogen concentrations and/or total uptake and observed adaptation to sandy soils. The superior adaptation of legumes in the experimental environment was demonstrated. It is suggested that crop legumes could make a more important agronomic contribution than hitherto in this and similar environments.

Sulfur nutrition of temperate pasture species. I. Effects of nitrogen supply on the external and internal sulfur requirements of subterranean clover and ryegrass

1984 ◽  
Vol 35 (3) ◽  
pp. 379 ◽  
Author(s):  
MA Gilbert ◽  
AD Robson
Keyword(s):  
Sulfur Content ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Nitrogen Supply ◽  
Nitrogen Application ◽  
Lolium Rigidum ◽  
Young Leaves ◽  
Glasshouse Experiment ◽  
Sulfur Nutrition

The effects of nitrogen supply on the external and internal sulfur requirements of subterranean clover (Trifolium subterraneum cv. Trikkala) and ryegrass (Lolium rigidum cv. Wimmera) were examined in a glasshouse experiment. Plants were grown for 28 and 42 days on a sulfur-deficient soil supplied with varying rates of sulfur. Nitrogen application increased the external requirement for sulfur of ryegrass by greatly stimulating growth and, to a lesser extent, sulfur content. Hence nitrogen application decreased sulfur concentrations in ryegrass. In subterranean clover there was relatively little effect of nitrogen application on the external requirement for sulfur because nitrogen did not greatly increase the sulfur content. Nitrogen application did not affect the external requirement for sulfur by changing the distribution of sulfur either between root and shoot or within shoots. The internal sulfur requirements, based either on sulfur concentrations or nitrogen to sulfur ratios, in the young leaves of both species were unaffected by nitrogen supply.

scholarly journals Comparative effects of grazing, herbicide or forage conservation on barley grass content in Trifolium subterraneum L. clover-based pasture

2019 ◽  
Vol 70 (9) ◽  
pp. 800
Author(s):  
John W. Piltz ◽  
Simon J. Flinn ◽  
Leslie A. Weston
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Annual Ryegrass ◽  
Lolium Rigidum ◽  
Herbicide Application ◽  
High Quality ◽  
Harvest Timing

Barley grass (Hordeum spp.) is a relatively short lived annual that provides high quality grazing early in the season, but its seed heads cause contamination of wool and carcasses, and may irritate the mouth, eyes and nose of sheep. Treatments were imposed on established subterranean clover (Trifolium subterraneum L.) annual pasture in the same plots for three consecutive years (2015 to 2017) to evaluate changes in barley grass content. Treatments included: grazing alone (G), herbicide followed by grazing (HG), or a forage conservation harvest in early October, late October or early November consistent with an early silage harvest (ES), late silage harvest (LS) or hay cut (H). Grazing plus herbicide markedly reduced (P < 0.05) barley grass numbers compared with all other treatments, but increased (P < 0.05) the growth of annual ryegrass (Lolium rigidum L.). ES reduced (P < 0.05) barley grass and increased (P < 0.05) subterranean clover compared with H, but broadleaf weed content benefitted by LS in contrast to either ES or H. Although herbicide application was the most effective method for barley grass control, forage harvest timing could be used to beneficially manipulate pasture composition.

Vesicular-arbuscular mycorrhizas and soil salinity

Mycorrhiza ◽  
1993 ◽  
Vol 4 (2) ◽  
pp. 45-57 ◽  
Author(s):  
S. Juniper ◽  
L. Abbott
Keyword(s):  
Soil Salinity ◽  
Arbuscular Mycorrhizas ◽  
Vesicular Arbuscular

Anisotropic Microstructure of Plasma-Sprayed Deposits

1998 ◽  
Author(s):  
J. lavsky ◽  
G.G. Long ◽  
A.J. Allen ◽  
L. Leblanc ◽  
M. Prystay ◽  
...  
Keyword(s):  
Small Angle Neutron Scattering ◽  
Size Range ◽  
Measurement Techniques ◽  
Quantitative Information ◽  
Underlying Structure ◽  
Impregnation Process ◽  
Direct Technique ◽  
Plasma Sprayed ◽  
The Relationship ◽  
Different Parts

Abstract The microstructure of plasma-sprayed deposits (PSD) is dominated by two void systems - interlamellar pores and intralamellar cracks - each with a different anisotropy. Varying anisotropics and crack-to-pore ratios within PSDs are responsible for the anisotropic properties observed in the deposits. While it is difficult to apply standard porosity measurement techniques to the assessment of anisotropic microstructures, novel techniques utilizing different approaches have recently emerged. Image analysis (IA) of impregnated PSD samples is the most direct technique. The structure is stabilized by impregnation and then polished and imaged. The limitations of IA lie in the impregnation process and in the subsequent polishing. Also, the images produced from anisotropic materials can be difficult to interpret quantitatively. The technique of small-angle neutron scattering (SANS) has recently been successfully applied to the study of PSDs. The major advantages of SANS are that it does not require sample preparation and that quantitative information can be gotten about the separate crack and pore systems, including their distinctive anisotropics. However, the relationship between the SANS results and the underlying structure is more complex and less intuitive than for IA, and the availability of the SANS technique is limited by the need to have access to a powerful neutron source, such as a reactor. Also, the two techniques present different views of the microstructure because of the different sensitivities in different parts of the size range. This paper compares results from IA and SANS from a set of thick plasma-sprayed ceramic deposits possessing a range of crack/pore microstructures, and discusses how the two techniques might complement one another.

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