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.

Phytophthora clandestina. [Descriptions of Fungi and Bacteria].

1991 ◽  
Author(s):  
G. Hall
Keyword(s):  
Geographical Distribution ◽  
Plant Pathogen ◽  
Root Rot ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Moist Soil

Abstract A description is provided for Phytophthora clandestina. Information is included on the disease caused by the organism, its transmission, geographical distribution, and hosts. HOSTS: Trifolium subterraneum. DISEASE: Root rot of subterranean clover; a facultatively necrotrophic plant pathogen. In field plants, black necrotic lesions develop 1-4 cm below the soil surface extending into the stele and causing orange-brown to brown tissue discoloration. Dry matter can be reduced by 71% (69, 5030). GEOGRAPHICAL DISTRIBUTION: Australasia & Oceania; Australia (NSW, WA, Vic.) TRANSMISSION: Presumably by zoospores released in moist soil. Oospores may act as perennating structures.

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.

The interrelation of burr burial, seed yield and dormancy in strains of subterranean clover

1976 ◽  
Vol 27 (6) ◽  
pp. 787 ◽  
Author(s):  
WJ Collins ◽  
CM Francis ◽  
BJ Quinlivan
Keyword(s):  
Seed Weight ◽  
Initial Level ◽  
Seed Viability ◽  
Selection Criterion ◽  
Subterranean Clover ◽  
Viable Seed ◽  
Individual Seed ◽  
Wide Range ◽  
Embryo Dormancy ◽  
Simple Selection

Prevention of burr burial drastically reduced the yield of viable seed in subterranean clover. This occurred through reductions in total burr number, number of mature burrs, number of seeds per burr, individual seed weight and seed viability. Strains differed markedly in their ability to produce seed in unburied burrs. A simple selection criterion based on changes in individual seed weight was proposed as a guide to screening for this character. When this criterion was applied to a wide range of strains, it appeared that later-maturing types were the most capable at producing seed in unburied burrs. The initial level of hardseededness was lower in seed from unburied burrs; also the rate of breakdown of hardseededness was faster in this seed, although the size of the effect varied between strains. Defoliation during the flowering period increased the initial level of hardseededness in seed from both buried and unburied burrs. Seed produced in buried burrs generally had a faster rate of breakdown of embryo dormancy than seed from unburied burrs, although the response varied between strains. The implications of these findings for future breeding and improvement in subterranean clover are discussed.

scholarly journals Changes in Germination Promotion and Inhibition in Seed Extracts of Subterranean Clover (Trifolium Subterraneum L.) Related to Dormancy and Germination

1971 ◽  
Vol 24 (4) ◽  
pp. 897 ◽  
Author(s):  
MG Walker
Keyword(s):  
Ethyl Acetate ◽  
Paper Chromatography ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Germination Inhibitors ◽  
Aqueous Fraction ◽  
Clover Seed ◽  
Seed Extracts

Seeds of two varieties of T. BUbterraneum were extracted after imbibing water for various periods. The extracts were partitioned into water and ethyl acetate, purified by paper chromatography, and germination.modifying activity measured by a subterranean clover seed bioassay. As imbibition proceeded, the balance of germination inhibitors and promo tors in the aqueous fraction remained fairly constant in the dormant variety, but changed "rapidly in the non-dormant variety. The activity in the ethyl acetate fractions of both varieties also changed rapidly, but for the dormant variety the final balance was inhibitory, and in the non-dormant variety promotory.

Mechanisms regulating germination in seeds of Stylosanthes

1975 ◽  
Vol 26 (2) ◽  
pp. 281 ◽  
Author(s):  
CJ Gardener
Keyword(s):  
Water Content ◽  
Seed Coat ◽  
Initial Level ◽  
Soil Surface ◽  
Germination Inhibitors ◽  
Hard Seed ◽  
Embryo Dormancy ◽  
Seed Coats ◽  
Water Contents ◽  
Soil Water Contents

Seed coat impermeability, embryo dormancy, decline in embryo vigour and the effect of adhering pods on germination were measured monthly on 15 lines of Stylosanthes which had weathered on the soil surface. The effect of pod and seed coat on imbibition was investigated in S. humilis over a range of soil water contents. The level of impermeability of newly harvested seed was initially high for all lines, but the rates of loss varied both between and within species, which indicated the possibility of screening for residual hard seed. The lines also differed in their ability to maintain impermeability over a 14-day germination period. The initial level of embryo dormancy varied between species but the protection afforded against germination was short lived. Decline in embryo vigour appeared to be partly caused by the testa restricting the radicle mechanically. The presence of pods enclosing the seed reduced germination by a mean of 15.4%, but this ranged from 1% in a line of S. guyanensis with thin papery pods to 42% in a line of S. viscosa with thick strong pods. There was no evidence of germination inhibitors in either pods or seed coats, but both restricted the entry of water into the seed. Imbibed seed could be dehydrated without damage provided the radicle had not emerged from the seed coat. This occurred when the water content of the seed reached 90%.

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.

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 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.

The influence of seed size and depth of sowing on pre-emergence and early vegetative growth of subterranean clover (Trifolium subterraneum L.)

1956 ◽  
Vol 7 (2) ◽  
pp. 98 ◽  
Author(s):  
JN Black
Keyword(s):  
Leaf Area ◽  
Seed Size ◽  
Vegetative Growth ◽  
Dry Matter ◽  
Relative Rate ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Dry Weight ◽  
Total Leaf Area ◽  
Pot Culture

Changes in the pre-emergence distribution of dry matter in subterranean clover (Trifolium subterraneum L.) variety Bacchus Marsh were followed at 21°C, using three sizes of seed and three depths of sowing, ½, 1¼, and 2 in. Decreasing seed size and increasing depth of sowing both reduce the weight of the cotyledons a t emergence. Seed of the three sizes were sown a t three depths in pot culture a t staggered intervals so that emergence was simultaneous. Dry weight in the early vegetative stage was proportional to seed size, and total leaf area and leaf numbers showed similar trends. Plants of each seed size grew at the same relative rate. No effect of depth of sowing could be detected, and this was shown to be due to the cotyledon area a t emergence being constant for any given seed size, regardless of varying depth of sowing and hence of cotyledon weight. It was concluded that seed size in a plant having epigeal germination and without endosperm is of importance: firstly, in limiting the maximum hypocotyl elongation and hence depth of sowing, and secondly, in determining cotyledon area. Cotyledon area in turn influences seedling growth, which is not affected by cotyledon weight. Once emergence has taken place, cotyledonary reserves are of no further significance in the growth of the plants.

CANTERBURY EXPERIENCE WITH SUBTERRANEAN CLOVER (Trifolium subterraneum)

1935 ◽  
pp. 64-68
Author(s):  
H. Neave ◽  
C.H. Hewlett
Keyword(s):  
Personal Experience ◽  
Subterranean Clover ◽  
Trifolium Subterraneum

The information contained in this paper is principally first-hand knowledge extending over a period of six years gained from personal experience from our own "Oakleigh" farm.

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