Nodulation and growth of pasture legumes with naturalised soil rhizobia.2. Balansa clover (Trifolium michelianum Savi)

2002 ◽  
Vol 42 (7) ◽  
pp. 939 ◽  
Author(s):  
R. A. Ballard ◽  
A. D. Craig ◽  
N. Charman
Keyword(s):  
Rhizobium Leguminosarum ◽  
Widespread Occurrence ◽  
Pasture Legumes ◽  
Cultivar Selection ◽  
Eastern Australia ◽  
Commercial Cultivars ◽  
Commercial Inoculant ◽  
Inoculant Strain ◽  
History Of ◽  
Trifolium Michelianum

Balansa clover (Trifolium michelianum Savi) is grown widely across southern and eastern Australia. The presence of suitable rhizobia (Rhizobium leguminosarum bv. trifolii) for this species of clover, and their ability to form an effective symbiosis, was assessed in a survey of 43 soils collected from across Australia. The effectiveness of the soil rhizobia is compared with that of strains WU95 and WSM409. The study confirmed the widespread occurrence of clover rhizobia in Australian soils. No clover rhizobia were detected in 6 of the 43 soils and this was probably associated with a history of clover absence at these soil locations. Thirty of the soils contained more than 500 rhizobia per gram. These rhizobia varied from highly effective for soil T2 (128% of WSM409) through to ineffective for soil V9 (22% of WSM409). Few soil inoculants were more effective than strain WSM409. Commercial inoculant strain WSM409 was generally more effective than former inoculant strain WU95.The suboptimal performance of the rhizobia in many of the soils indicates that there is an opportunity to improve the level of nitrogen fixation by balansa clover in the field. Bearing in mind the difficulties associated with the introduction and persistence of applied inoculant strains, cultivar selection is considered as an approach to improve the symbiosis. However, this study indicated little variation in the performance of the 3 commercial cultivars, Frontier, Paradana and Bolta, in this regard.

Performance of annual pasture legumes in cropping rotations in the cool temperate zone of south-eastern Australia

2004 ◽  
Vol 44 (9) ◽  
pp. 863 ◽  
Author(s):  
X. Zhang ◽  
P. M. Evans ◽  
P. A. Riffkin
Keyword(s):  
Dry Matter ◽  
Subterranean Clover ◽  
Pasture Legumes ◽  
Matter Production ◽  
Eastern Australia ◽  
Cool Temperate ◽  
Seedling Dynamics ◽  
Production Growth ◽  
Before And After ◽  
Trifolium Michelianum

The relative performance of 3 alternative pasture legumes, in comparison with subterranean clover, grown in a 1:1 pasture:crop rotation was investigated during 1997–2001, at 2 sites in the high rainfall (>500 mm/year) zone of southern Australia. Seedling densities of the pasture legumes (before and after crop) were examined, along with herbage dry matter production, growth pattern and seed production. After 2 cycles of a 1:1 pasture:crop rotation, average seedling densities of balansa (Trifolium michelianum Savi var. michelianum), Persian (T. resupinatum L. var. resupinatum Gib. and Belli), arrowleaf (T. vesiculosum Savi.) and subterranean (T. subterraneum L.) clovers at the 2 sites were 6810, 2910, 680 and 630 plants/m2, respectively. Average cumulative herbage mass in 2001 was 7.49, 5.21, 8.53 and 7.76 t DM/ha.year, respectively. All clovers produced a large seed pool: balansa, 71.8 g/m2; subterranean, 38.9 g/m2; Persian, 35.5 g/m2; and arrowleaf, 35.4 g/m2. The results suggest that a 1:1 pasture:crop rotation is sustainable, in terms of pasture seed–seedling dynamics for each of the legumes, and that under this system the pasture legumes need to be sown only once.

Analytical Electron Microscopy of Extraterrestrial Ice Analogs

1990 ◽  
Vol 48 (1) ◽  
pp. 594-595
Author(s):  
D.F. Blake ◽  
LJ. Allamandola ◽  
G. Palmer ◽  
A. Pohorille
Keyword(s):  
Solar System ◽  
Analytical Electron Microscopy ◽  
Biogenic Elements ◽  
Widespread Occurrence ◽  
Interstellar Ice ◽  
Analytical Electron ◽  
History Of ◽  
Interstellar Material ◽  
Astrophysical Ices ◽  
Interstellar Molecular Clouds

The natural history of the biogenic elements H, C, N, O, P and S in the cosmos is of great interest because it is these elements which comprise all life. Material ejected from stars (or pre-existing in the interstellar medium) is thought to condense into diffuse bodies of gravitationally bound gas and dust called cold interstellar molecular clouds. Current theories predict that within these clouds, at temperatures of 10-100° K, gases (primarily H2O, but including CO, CO2, CH3OH, NH3, and others) condense onto submicron silicate grains to form icy grain mantles. This interstellar ice represents the earliest and most primitive association of the biogenic elements. Within these multicomponent icy mantles, pre-biotic organic compounds are formed during exposure to UV radiation. It is thought that icy planetesimals (such as comets) within our solar system contain some pristine interstellar material, including ices, and may have (during the early bombardment of the solar system, ∼4 Ga) carried this material to Earth.Despite the widespread occurrence of astrophysical ices and their importance to pre-biotic organic evolution, few experimental data exist which address the relevant phase equilibria and possible structural states. A knowledge of the petrology of astrophysical ice analogs will allow scientists to more confidently interpret astronomical IR observations. Furthermore, the development and refinement of procedures for analyzing ices and other materials at cryogenic temperatures is critical to the study of materials returned from the proposed Rosetta comet nucleus and Mars sample return missions.

Distribution and life history of caridean shrimps in regulated lowland rivers in southern Australia

2004 ◽  
Vol 55 (3) ◽  
pp. 295 ◽  
Author(s):  
A. J. Richardson ◽  
J. E. Growns ◽  
R. A. Cook
Keyword(s):  
Life History ◽  
Life Stages ◽  
Lowland Rivers ◽  
Flow Alteration ◽  
Eastern Australia ◽  
History Of ◽  
Paratya Australiensis ◽  
Juvenile Stages ◽  
Shrimp Abundance ◽  
Large Adult

Caridean shrimps are an integral component of lowland river ecosystems in south-eastern Australia, but their distributions may be affected by flow alteration. Monthly shrimp samples were collected from slackwaters in three hydrologically distinct sections of the heavily regulated Campaspe River and the less regulated Broken River for three consecutive years. The distributions of Paratya australiensis, Caridina mccullochi and Macrobrachium australiense, along with their life history in river sections with different hydrology are outlined. Paratya australiensis and M. australiense occurred in all sections, but C. mccullochi was absent from sections of the Campaspe River that received irrigation flows during summer/autumn. Shrimp larvae were most abundant in summer (December–February) and juvenile recruitment continued through to mid autumn (April). Breeding and recruitment of P. australiensis occurred for longer than other shrimps. Apart from large adult and berried M. australiense, all life stages of shrimps commonly occurred in slackwaters, particularly the larval and juvenile stages. Irrigation flows in summer/autumn probably adversely affect the size, extent and arrangement of slackwaters, at a time when they may be critical habitats for C. mccullochi larval development and recruitment. Dams and weirs in the Campaspe River may have influenced shrimp abundance and the timing of breeding.

Hardseededness and pattern of hard seed breakdown in Sardinian populations of Medicago polymorpha under field conditions

1996 ◽  
Vol 126 (2) ◽  
pp. 161-168 ◽  
Author(s):  
C. Porqueddu ◽  
A. Loi ◽  
P. S. Cocks
Keyword(s):  
Mediterranean Basin ◽  
Seedling Emergence ◽  
Experimental Period ◽  
First Year ◽  
Medicago Polymorpha ◽  
Hard Seed ◽  
Pasture Legumes ◽  
Commercial Cultivars ◽  
Previous Summer ◽  
The Mediterranean Basin

SUMMARYThe hardseededness and pattern of hard seed breakdown of 35 accessions of Medicago polymorpha, collected in Sardinia, were compared with Circle Valley, an Australian cultivar, near Sassari, northern Sardinia. The seed was produced in three consecutive years (1991–93), and the hardseededness measured at intervals in trie field during the summer following its production. The results were related to previously measured pod characteristics that separated the varieties polymorpha and vulgarisThe variety polymorpha, which had been collected mainly from coastal regions, was harder seeded than the variety vulgaris, which had been collected mainly from cooler, inland regions. Wherever the origin, hardseededness levels remained > 85% even in the year when seed softening was greatest (1992). In other years means of 94% (1991) and 97% (1993) of seed remained hard in late September. In 1992 and 1993 most hard seed breakdown occurred between early August and early September, while in 1991 hard seed breakdown occurred in September itself. There was little difference between varieties in the pattern of hard seed breakdown. Seedling emergence was related to the amount of seed that became soft during the previous summer. The results also confirmed that hard seeds soften sequentially from the proximal end of the pod (nearest the calyx) to the distal end.The Australian cultivar was one of the hardest seeded accessions, showing very little hard seed breakdown during the experimental period. This result highlights the importance of selecting pasture legumes under the conditions in which they are to be used: in Australia, cultivar Circle Valley usually loses some 20% of its hardseededness in the first year, comparable with the softest Sardinian accessions in Sardinia. Even among the Sardinian accessions, most were probably too hard seeded in 1993. Nevertheless it is likely that material in this experiment will be released as commercial cultivars for Sardinia and other similar environments in the Mediterranean basin.

Performance and weed-suppressive potential of selected pasture legumes against annual weeds in south-eastern Australia

2019 ◽  
Vol 70 (2) ◽  
pp. 147 ◽  
Author(s):  
Sajid Latif ◽  
Saliya Gurusinghe ◽  
Paul A. Weston ◽  
William B. Brown ◽  
Jane C. Quinn ◽  
...  
Keyword(s):  
Subterranean Clover ◽  
Weed Suppression ◽  
Weed Species ◽  
Mixed Stands ◽  
South Eastern ◽  
Pasture Legumes ◽  
Eastern Australia ◽  
Weed Suppressive Ability ◽  
Weed Infestation ◽  
South Eastern Australia

Mixed farming systems have traditionally incorporated subterranean clover (Trifolium subterraneum L.) and lucerne (Medicago sativa L.) as key components of the pasture phase across south-eastern Australia. However, poor adaptation of subterranean clover to acidic soils, insufficient and inconsistent rainfall, high input costs, soil acidification and the emergence of herbicide-resistant weeds have reduced efficacy of some traditional clover species in recent years. To overcome these challenges, numerous novel pasture species have been selectively improved and released for establishment in Australia. Despite their suitability to Australian climate and soils, limited knowledge exists regarding their weed-suppressive ability in relation to establishment and regeneration. Field trials were therefore conducted over 3 years in New South Wales to evaluate the suppressive potential of selected pasture legume species and cultivars as monocultures and in mixed stands against dominant annual pasture weeds. Pasture and weed biomass varied significantly between pasture species when sown as monocultures, but mixtures of several species did not differ with regard to establishment and subsequent weed infestation. Arrowleaf clover (T. vesiculosum Savi.) and biserrula (Biserrula pelecinus L.) cv. Casbah showed improved stand establishment, with higher biomass and reduced weed infestation compared with other pasture species. Generally, weed suppression was positively correlated with pasture biomass; however, yellow serradella (Ornithopus compressus L.) cv. Santorini exhibited greater weed suppression than other pasture legumes while producing lower biomass, thereby suggesting a mechanism other than competition for resources affecting weed-suppressive ability. Over the period 2015–17, arrowleaf clover and biserrula cv. Casbah were generally the most consistent annual pasture legumes with respect to yearly regeneration and suppression of annual pasture weed species.

Comparative mitochondrial phylogeography of two legless lizards (Pygopodidae) from Queensland’s fragmented woodlands

2020 ◽  
Vol 66 (3-4) ◽  
pp. 142-150
Author(s):  
Jessica Worthington Wilmer ◽  
Andrew P. Amey ◽  
Carmel McDougall ◽  
Melanie Venz ◽  
Stephen Peck ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Evolutionary History ◽  
The West ◽  
European Settlement ◽  
Low Genetic Diversity ◽  
Eastern Australia ◽  
Wide Range ◽  
History Of ◽  
Open Forests ◽  
Fossorial Species

Sclerophyll woodlands and open forests once covered vast areas of eastern Australia, but have been greatly fragmented and reduced in extent since European settlement. The biogeographic and evolutionary history of the biota of eastern Australia’s woodlands also remains poorly known, especially when compared to rainforests to the east, or the arid biome to the west. Here we present an analysis of patterns of mitochondrial genetic diversity in two species of Pygopodid geckos with distributions centred on the Brigalow Belt Bioregion of eastern Queensland. One moderately large and semi-arboreal species, Paradelma orientalis, shows low genetic diversity and no clear geographic structuring across its wide range. In contrast a small and semi-fossorial species, Delma torquata, consists of two moderately divergent clades, one from the ranges and upland of coastal areas of south-east Queensland, and other centred in upland areas further inland. These data point to varying histories of geneflow and refugial persistance in eastern Australia’s vast but now fragmented open woodlands. The Carnarvon Ranges of central Queensland are also highlighted as a zone of persistence for cool and/or wet-adapted taxa, however the evolutionary history and divergence of most outlying populations in these mountains remains unstudied.

Supercooling on the lunar surface: a review of analogue information

1977 ◽  
Vol 285 (1327) ◽  
pp. 207-217 ◽  
Keyword(s):  
Lunar Surface ◽  
Growth Conditions ◽  
Controlled Cooling ◽  
Widespread Occurrence ◽  
Lunar Rocks ◽  
History Of ◽  
Varied Composition ◽  
Published Research ◽  
Guide Lines ◽  
Zoned Plagioclase

The crystallization of the principal constituent minerals, olivine, pyroxene and plagioclase, in dendritic or skeletal forms, is much more characteristic of lunar than of terrestrial igneous rocks. This type of crystallization is found in lunar rocks of such varied composition as olivine-normative mare basalt (12009) and spinel troctolite (62295). Olivine and pyroxene often occur as skeletal phenocrysts and the stage at which they crystallized is of crucial significance to interpretations of the genesis and cooling history of the porphyritic lavas. Furthermore, there is a widespread occurrence of glass and of immature, radiate crystallization, particularly of highly zoned pyroxenes and zoned plagioclase. Most of these characteristics are a response to a range of supercooling and rapid crystal-growth conditions that are typically lunar. The research value of direct comparison with terrestrial analogues is severely restricted, and the value of controlled cooling-rate experiments, with melts of appropriate compositions, is correspondingly enhanced. This need for information on the rapid consolidation of the lavas extruded on the Moon, and of impact liquids, has stimulated investigations of the phase petrology of supercooled melts. The evidence adduced from these analogue approaches is reviewed. Recently published research results based on this evidence have provided new guide-lines to interpreting crystallization on the lunar surface.

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