The germinability of soft seed of a number of strains of subterranean clover

1970 ◽  
Vol 10 (44) ◽  
pp. 293 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Carbon Dioxide ◽  
High Temperatures ◽  
Seed Treatment ◽  
Laboratory Tests ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dormant Seed ◽  
Seed Treatments ◽  
Embryo Dormancy

The effect of several seed treatments on germination of 13 strains of subterranean clover (Trifolium subterraneum) seed was examined at two constant temperatures in the laboratory. Tests were conducted on soft seed obtained after scarification of seed sampled on three occasions during the summer and autumn. Germinability varied between strains, but always increased with time after harvest ripeness. Leaching with water promoted some germination in even the most dormant seed. Treatment with carbon dioxide was effective in promoting germination at 20�C, but was less effective than leaching at 30�C. The results suggest that protection against germination by embryo dormancy is likely to be confined to conditions of comparatively high temperatures (>20�C) when associated with summer rains having little or no leaching effect.

scholarly journals Studies of Dormancy in the Seeds of Subterranean Clover (Trifolium Subterraneum L.) II. The Interaction of Time, Temperature, and Carbon Dioxide During Passage Out of Dormancy

1961 ◽  
Vol 14 (2) ◽  
pp. 173 ◽  
Author(s):  
LAT Ballard
Keyword(s):  
Carbon Dioxide ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dormancy Breaking ◽  
Temperature Dependent

The dormancy-breaking action of C02 on imbibed seeds of subterranean clover ('1'rijolium 8ubterraneum L.) is temperature dependent, the efficiency falling off sharrlly above 25�C and approaching zero at 30�C. Within the effective temp. erature range the action is rapid, exposure of seeds to CO2 for 6 hr having signifiC!,fit effect.

Flower initiation in Trifolium subterraneum L. II. Limitations by vernalization, low temperatures, and photoperiod, in the field at Canberra

1959 ◽  
Vol 10 (1) ◽  
pp. 17 ◽  
Author(s):  
FHW Morley ◽  
LT Evans
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Day Length ◽  
Flower Initiation ◽  
Inhibitory Effects ◽  
Low Field ◽  
The Times ◽  
Short Days

At various times throughout the winter, autumn-sown plants of five strains of subterranean clover were removed from the field to a series of day length and temperature treatments. The times to inflorescence initiation in all treatments were determined by dissection. As vernalization proceeded the requirement of all strains for long days was progressively reduced until, by midwinter, several strains had become virtually independent of day length. Similarly, with the progress of vernalization the inhibitory effects of high temperatures during short days became progressively less marked. Whereas exposure to long days at high temperatures greatly accelerated inflorescence initiation in all strains, long days at low field temperatures had little effect. Evidence is presented which suggests that the limiting effect of very low temperatures on initiation is due not only to retardation of the rate of inflorescence primordium formation (realization), but also to limitation of an inductive process other than vernalization and dark period inhibition. The flowering behaviour of the various strains is discussed in terms of their responses to the partial processes leading to inflorescence initiation, and the interrelationships of these processes are considered.

Flower initiation in Trifolium subterraneum L. 1. Analysis of the partial processes involved

1959 ◽  
Vol 10 (1) ◽  
pp. 1 ◽  
Author(s):  
LT Evans
Keyword(s):  
High Temperatures ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Controlled Environment ◽  
Flower Initiation ◽  
Inhibitory Process ◽  
Inhibitory Effects ◽  
Other Hand ◽  
Short Days

The influence of various temperature and photoperiod regimes on flower initiation and flowering in eight strains of T. subterraneum has been examined, using the controlled environment facilities of the Earhart Laboratory. Flower initiation in subterranean clover appears to be under the control of three interacting partial processes, two of which are synergistic and promotive while the third is inhibitory. The promotive processes are possibly both light-independent, one being favoured by high temperatures and the other (the vernalization process) by low temperatures. The inhibitory process, on the other hand, is restricted to the diurnal dark period and is favoured by high temperatures. The interaction between the vernalization and dark inhibitory processes is such that in the absence of dark inhibition no vernalization is required by any strain, while on. the other hand sufficient vernalization can apparently overcome all dark inhibitory effects. Treatment with gibberellic acid eliminates the need for vernalization by plants of at least one early-flowering strain when. grown in short days at high temperatures. The strains of subterranean clover differ markedly in their responses to the three partial processes. In their response to the dark inhibitory process two strains are more affected by night temperature than by night length, while in two other strains the opposite is the case, which suggests that the dark inhibitory process could be resolved into more than one component.

Plant population dynamics in subterranean clover and murex medic swards. I. Size and composition of the seed bank

1994 ◽  
Vol 45 (4) ◽  
pp. 913 ◽  
Author(s):  
MJ Blumenthal ◽  
RL Ison
Keyword(s):  
High Temperature ◽  
Seed Bank ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Controlled Environment ◽  
Plant Population Dynamics ◽  
Embryo Dormancy ◽  
Alternating Temperature ◽  
Total Seed

It is possible that the use of harder-seeded varieties of sub. clover (Trifolium subterraneum) and the recently domesticated murex medic (Medicago murex) may improve annual legume persistence in pasture leys. To determine the mechanisms of production and persistence in these two species, the size and composition of the seed bank were compared in four varieties of sub. clover and two lines of murex medic over a three-year period at Forbes in central-west N.S.W. The rate of breakdown of hardseed and the loss of high temperature dormancy was also studied in the same genotypes under conditions of alternating temperature in controlled environment cabinets. In terms of the size of the total seed bank, the sub. clover cultivar with the highest level of hardseed (Dalkeith) was the most successful genotype studied. This was the result of slower rates of hardseed breakdown compared to the other sub. clover cultivars, and better seed production compared to the two murex medic lines. Losses of seed from the seed bank were substantial, and were not all accounted for by germinated seedlings or grazing over summer. The sub. clover cultivars Junee and Seaton Park had the highest levels of high temperature embryo dormancy and the lowest proportion of seedlings germinating over summer. The level of sub. clover hardseed breakdown in the field corresponded well with the 60/15�C laboratory estimates of hardseed breakdown, even though soil surface temperatures over summer at Forbes were rarely in the range of 60/15�C.

Embryo dormancy in subterranean clover seeds. I. Environmental control

1971 ◽  
Vol 22 (4) ◽  
pp. 599 ◽  
Author(s):  
BJ Quinlivan ◽  
HI Nicol
Keyword(s):  
Temperature Change ◽  
Temperature Regime ◽  
Initial Level ◽  
Environmental Control ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moist Soil ◽  
Germination Inhibitors ◽  
Embryo Dormancy ◽  
Summer Temperatures

Embryo dormancy in seeds of subterranean clover (Trifolium subterraneum) is at a maximum at field maturity in the spring. High summer temperatures are the causative agent in the subsequent breakdown of embryo dormancy, the germination inhibitors in the seeds apparently being susceptible to heat. There is no evidence for germination inhibitors in the pod and burr material, nor is there any evidence to support the hypothesis of an environmentally imposed dormancy, for germination is relatively fast at 15 ? 25�C, a temperature regime equivalent to the daily temperature change of summer moist soil. There are differences between cultivars in the initial level of embryo dormancy and in the subsequent rate of breakdown.

scholarly journals Studies of Dormancy in the Seeds of Subterranean Clover (Trifolium Subterraneum L.)

1969 ◽  
Vol 22 (2) ◽  
pp. 279 ◽  
Author(s):  
LAT Ballard ◽  
AE Grant Lipp
Keyword(s):  
Carbon Dioxide ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Second Phase ◽  
Low Oxygen ◽  
Anaerobic Conditions ◽  
Breaking Dormancy ◽  
Low Concentrations ◽  
Stimulation Of ◽  
Oxygen Concentrations

When imbibed dormant subterranean clover seeds were exposed to low concentrations of oxygen for up to 6 days, and then transferred to either air or 100% oxygen atmospheres, germination was markedly increased above that of seeds held only in air. Stimulation of germination was similar whether the atmosphere of the second phase was air or 100% oxygen; it was maximal when that of the first phase contained no oxygen, and became insignificant above concentrations in the region of 5% oxygen. The additional germination was roughly proportional to the duration of exposure to low oxygen concentrations, and the effects of two separated exposures to low oxygen were additive. These effects could be produced only in those dormant samples whose seeds or embryos could also be made germinable by exposure to 2�5% carbon dioxide. At higher temperatures, anaerobic conditions were less effective in breaking dormancy, paralleling the reduced efficacy of carbon dioxide at these temperatures.

scholarly journals Studies of Dormancy in the Seeds of Subterranean Clover (Trifolium Subterraneum l.) I. Breaking of Dormancy by Carbon Dioxide and by Activated Carbon

1958 ◽  
Vol 11 (3) ◽  
pp. 246 ◽  
Author(s):  
LAT Ballard
Keyword(s):  
Carbon Dioxide ◽  
Activated Carbon ◽  
Activated Carbons ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Low Concentration ◽  
New Methods

Two new methods for breaking the dormancy of subterranean clover (Trifolium subterraneum L.) seeds are described, viz. treatment of imbibed seeds with a low concentration of carbon dioxide, and with activated carbons.

Competition among seedlings of perennial grasses, subterranean clover, white clover, and annual ryegrass in replacement series mixtures

2000 ◽  
Vol 51 (3) ◽  
pp. 377 ◽  
Author(s):  
G. M. Lodge
Keyword(s):  
White Clover ◽  
Plant Competition ◽  
Perennial Grass ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Perennial Grasses ◽  
Maximum Likelihood Estimates ◽  
Annual Ryegrass ◽  
Replacement Series ◽  
Successful Establishment

Seedlings of 3 perennial grasses, Danthonia linkii Kunthcv. Bunderra, D. richardsonii Cashmore cv. Taranna(wallaby grasses), and Phalaris aquatica L. cv. Sirosa,were each grown in replacement series mixtures with seedlings ofTrifolium repens L. (white clover),Trifolium subterraneum L. var. brachycalycinum (Katzn.et Morley) Zorahy & Heller cv. Clare (subterraneanclover), and Lolium rigidum L. (annual ryegrass). Plantswere sown 5 cm apart in boxes (45 by 29 by 20 cm) at a density of 307plants/m2. Maximum likelihood estimates were usedto derive parameters of a non-linear competition model using the dry matterweights of perennial grasses and competitors at 3 harvests, approximately 168,216, and 271 days after sowing. Intra-plant competition was examined inmonocultures of each species, grown at plant spacings of 2, 5, and 8 cm apartwith plants harvested at the above times.Competition occurred in all perennial grass–competitor mixtures, exceptin those of each perennial grass with white clover and thephalaris–subterranean clover mixture (Harvest 1) and those withD. richardsonii and phalaris grown with white clover(Harvest 2). For D. richardsonii (Harvests 1 and 2) andD. linkii (Harvest 1 only) grown with white clover andthe phalaris–subterranean clover (Harvest 1), the two species in themixture were not competing. In the phalaris–white clover mixture, eachspecies was equally competitive (Harvests 1 and 2). These differences incompetition and aggressiveness reflected differences in individual plantweights in monocultures where there was an effect (P < 0.05) of species ondry matter weight per box, but no significant effect of plant spacing.These data indicated that for successful establishment,D. richardsonii and D. linkiishould not be sown in swards with either subterranean clover or white clover,or where populations of annual ryegrass seedlings are likely to be high.Phalaris was more compatible with both white clover and subterranean clover,but aggressively competed with by annual ryegrass.

scholarly journals Gaseous combustion at high pressures. —Part X. The co-volume corrections, maximum temperatures and dissociation of steam and carbon dioxide in explosions

1928 ◽  
Vol 119 (782) ◽  
pp. 464-480
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Internal Energy ◽  
High Temperatures ◽  
High Pressures ◽  
Internal Combustion ◽  
Systematic Survey ◽  
Explosion Method ◽  
Maximum Temperatures ◽  
Very High

During the researches upon high-pressure explosions of carbonic oxide-air, hydrogen-air, etc., mixtures, which have been described in the previous papers of this series, a mass of data has been accumulated relating to the influence of density and temperature upon the internal energy of gases and the dissociation of steam and carbon dioxide. Some time ago, at Prof. Bone’s request, the author undertook a systematic survey of the data in question, and the present paper summarises some of the principal results thereof, which it is hoped will throw light upon problems interesting alike to chemists, physicists and internal-combustion engineers. The explosion method affords the only means known at present of determining the internal energies of gases at very high temperatures, and it has been used for this purpose for upwards of 50 years. Although by no means without difficulties, arising from uncertainties of some of the assumptions upon which it is based, yet, for want of a better, its results have been generally accepted as being at least provisionally valuable. Amongst the more recent investigations which have attracted attention in this connection should be mentioned those of Pier, Bjerrum, Siegel and Fenning, all of whom worked at low or medium pressures.

scholarly journals Host plant recognition by the root feeding clover weevil, Sitona lepidus (Coleoptera: Curculionidae)

2004 ◽  
Vol 94 (5) ◽  
pp. 433-439 ◽  
Author(s):  
S.N. Johnson ◽  
P.J. Gregory ◽  
P.J. Murray ◽  
X Zhang ◽  
I.M. Young
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Plant Roots ◽  
Grass Species ◽  
Movement Rates ◽  
Sitona Lepidus ◽  
Macro Scale ◽  
Significant Difference ◽  
Invasive Techniques ◽  
Root Feeding

AbstractThis study investigated the ability of neonatal larvae of the root-feeding weevil, Sitona lepidus Gyllenhal, to locate white clover Trifolium repens L. (Fabaceae) roots growing in soil and to distinguish them from the roots of other species of clover and a co-occurring grass species. Choice experiments used a combination of invasive techniques and the novel technique of high resolution X-ray microtomography to non-invasively track larval movement in the soil towards plant roots. Burrowing distances towards roots of different plant species were also examined. Newly hatched S. lepidus recognized T. repens roots and moved preferentially towards them when given a choice of roots of subterranean clover, Trifolium subterraneum L. (Fabaceae), strawberry clover Trifolium fragiferum L. (Fabaceae), or perennial ryegrass Lolium perenneL. (Poaceae). Larvae recognized T. repens roots, whether released in groups of five or singly, when released 25 mm (meso-scale recognition) or 60 mm (macro-scale recognition) away from plant roots. There was no statistically significant difference in movement rates of larvae.

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