Fate of annual pasture legumes seeds on a two-way thermo-gradient plate

2002 ◽  
Vol 24 (2) ◽  
pp. 227 ◽  
Author(s):  
G. M. Lodge ◽  
R. D. B. Whalley
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Vicia Villosa ◽  
Temperature Range ◽  
Pasture Legumes ◽  
Maximum Value ◽  
High Germination ◽  
Annual Medics ◽  
Gradient Plate ◽  
Seed Fates

Effects of diurnally alternating temperatures (5/5–45/45�C) were examined on a two-way thermogradient plate for non-dormant seeds of 14 annual pasture legumes. Seed fates (germination, temperature induced non-viability and temperature induced dormancy) were determined from daily seed counts over a 14-day period on-plate and a further 14 days after removal from the plate. These data clearly demonstrate the existence and extent of seed fates other than germination. Maximum dormancy occurred over a broad range of temperatures for seeds of Trifolium subterraneum L. var. subterraneum (Katzn. et Morley) Zohary and Heller cv. Woogenellup (40/35–30/25�C), Astragalus hamosus L. cv. Ioman (40/25–30/5�C) and Trifolium hirtum All. cv. Hykon (35/30–30/5�C). In contrast, maximum dormancy occurred over a narrow temperature range for Medicago truncatula Gaertn. var. truncatula cv. Paraggio (35/30–30/25�C), M. aculeata Willd. var. inermis (Aschers.) Heyn (30/25 and 30/20�C), and M. minima L. (35/20–35/5�C) seeds. Generally, non-viability was highest in all legumes when temperatures were greater than 35/30�C and not significantly different from the maximum value (100%) at temperatures greater than 40/30�C. At temperatures less than 35/30�C non-viability was less than the maximum (P<0.05) for seeds of all legumes, except M. truncatula cvs. Jemalong and Sephi, M. aculeata, and Vicia villosa ssp. dasycarpa (Ten.) Cav. cv. Namoi. Compared with the other subterranean clover cultivars germination levels T. subterraneum var. brachycalycinum (Katzn. et Morley) Zohary and Heller cv. Clare seeds were not significantly different from the maximum value at higher temperatures. In all annual medics, except M. aculeata germination was not significantly different to the maximum at temperatures greater than 25/20�C, with high germination (P<0.05) occurring at 30/25�C in Jemalong and M. scutellata (L.) Mill cv. Sava and at 30/20�C in Paraggio, Sephi, M. minima and M. polymorpha L. Maximum germination in Ioman and Hykon seeds occurred over a broader temperature range (35/20–15/10�C and 30/20–15/5�C, respectively) than in Namoi (30/15�C and 25/20–25/5�C). Probable implications of these data for field emergence of non-dormant seeds and soil seed reserves are discussed.

Breeding and farming system opportunities for pasture legumes facing increasing climate variability in the south-west of Western Australia

2012 ◽  
Vol 63 (9) ◽  
pp. 840 ◽  
Author(s):  
C. K. Revell ◽  
M. A. Ewing ◽  
B. J. Nutt
Keyword(s):  
Western Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Farming System ◽  
Annual Rainfall ◽  
The South ◽  
Pasture Legumes ◽  
South West ◽  
Annual Medics ◽  
Phosphorus And Potassium

The south-west of Western Australia has experienced a declining trend in annual rainfall and gradual warming over the last 30 years. The distribution of rainfall has also changed, with lower autumn rainfall, patchy breaks to the season, and shorter springs. This has important implications for the productivity of legume pastures in the region, which is dominated by annual species, particularly subterranean clover (Trifolium subterraneum L.), annual medics (Medicago spp.), serradella (Ornithopus spp.), and biserrula (Biserrula pelecinus L.). For annual pasture legumes, appropriate patterns of seed softening and germination behaviour, efficiency of phosphorus and potassium uptake, responses to elevated levels of atmospheric CO2, and drought resistance of seedlings and mature plants will assume increasing importance. While these traits can be targeted in pasture breeding programs, it will also be important to exploit farming system opportunities to optimise the annual legume component of the feed base. These opportunities may take the form of incorporating strategic shrub reserves and grazing crops to allow for pasture deferment in autumn–winter. Perennial forages may become more important in this context, as discussed in terms of the development of the perennial legume tedera (Bituminaria bituminosa var. albomarginata C.H. Stirton).

AGWEST Sothis: Trifolium dasyurum (eastern star clover)

2007 ◽  
Vol 47 (12) ◽  
pp. 1512 ◽  
Author(s):  
A. Loi ◽  
B. J. Nutt ◽  
C. K. Revell ◽  
R. Snowball
Keyword(s):  
Dry Matter ◽  
Eastern Mediterranean ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Late Winter ◽  
Long Period ◽  
Pasture Legumes ◽  
Mediterranean Regions ◽  
World Agriculture ◽  
Annual Medics

Trifolium dasyurum C. Presl. (eastern star clover) is a species native to the eastern Mediterranean regions. AGWEST Sothis is the first cultivar of eastern star clover released to world agriculture. It has high levels of dry matter and seed production and seed can be harvested with modified grain harvesters. AGWEST Sothis is suitable for use on acid and alkaline fine-textured soils in low to medium rainfall areas (325–450 mm) in southern Australia. AGWEST Sothis is an early to mid-maturing variety, flowering ~100 days after emergence in Perth, Australia. Individual seeds weigh ~6 mg. In regenerating stands, AGWEST Sothis germinates very late in the season compared with traditional pasture legumes such as subterranean clover (Trifolium subterraneum L.) and annual medics (Medicago spp.) and weeds. The delay in germination allows the use of non-selective herbicides or intensive grazing after the break of season for a long period 3–6 weeks to obtain >90% control of troublesome crop weeds. In spite of its late germination, AGWEST Sothis grows rapidly in late winter/spring and can become a productive legume-dominant pasture for grazing or forage conservation.

Fungal diseases of temperate annual pasture legumes in southern Queensland

1999 ◽  
Vol 39 (6) ◽  
pp. 699 ◽  
Author(s):  
J. M. Mackie ◽  
D. L. Lloyd ◽  
M. J. Ryley ◽  
J. A. G. Irwin
Keyword(s):  
Rhizoctonia Solani ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Fungal Diseases ◽  
Colletotrichum Trifolii ◽  
Annual Legumes ◽  
Pasture Legumes ◽  
Colletotrichum Destructivum ◽  
Annual Medics ◽  
Annual Medicago

Summary. Diseases of temperate annual pasture legumes in subtropical southern Queensland were surveyed during 1992 and 1993. The following pathogenic organisms were recorded: Colletotrichum trifolii, Stemphylium vesicarium, Oidium sp., Uromyces anthyllidis, Uromyces striatus and Pseudopeziza medicaginis from annual Medicago spp.; Rhizoctonia solani and Colletotrichum destructivum from Ornithopus spp.; and Oidium sp. from Trifolium subterraneum. Three of these disease interactions had not been previously recorded in Queensland and 5 were new reports for Australia. Rust was the most frequently observed and widespread disease on annual medics (44% of M. polymorpha samples). All other diseases of annual medics were found infrequently (2–18% of samples). In contrast, both serradella and subterranean clover were relatively free from any diseases. The years during which the survey was conducted were dry (as low as 31% of mean March–October rainfall) and the expression of disease may have been restricted. Nevertheless, this improved knowledge of diseases of temperate annual legumes in southern Queensland will assist in the future selection and breeding of suitable cultivars for use in the subtropics.

Flower initiation in pasture legumes. I. Factors affecting flower initiation in Trifolium subterraneum L.

1955 ◽  
Vol 6 (2) ◽  
pp. 211 ◽  
Author(s):  
Y Aitken
Keyword(s):  
Low Temperature ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Cold Period ◽  
Effect Of Temperature ◽  
Flower Initiation ◽  
Temperature Level ◽  
Factors Affecting ◽  
Pasture Legumes ◽  
Precise Knowledge

The value of the annual legume Trifolium subterraneum L. (subterranean clover) in Australian agriculture warrants more precise knowledge of factors affecting flowering and prolific seeding. The effect of temperature and photoperiod on flower initiation in early and later flowering varieties has been investigated in an effort to determine the geographical limits of the use of subterranean clover in Australia. At any time of sowing, the length of the growing season of a variety depends greatly on the variety's response to the temperature level and to the photoperiod of the first few weeks after germination. In all varieties of subterranean clover so far examined flower initiation is accelerated by a period of low temperature. In the later varieties, flower initiation is prevented by an insufficient period of low temperature. The length of the necessary cold period is shortened under longer photoperiod. Early varieties are early flowering because they do not require so long a cold period or so low a temperature as late varieties.

Differential tolerance of annual medics, Nungarin subterranean clover and hedge mustard to broadleaf herbicides

1992 ◽  
Vol 32 (1) ◽  
pp. 49 ◽  
Author(s):  
RR Young ◽  
KJ Morthorpe ◽  
PH Croft ◽  
H Nicol
Keyword(s):  
Sodium Salt ◽  
Dry Matter ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Effective Control ◽  
Medicago Littoralis ◽  
Annual Medics ◽  
Seed Yields ◽  
Test Plants ◽  
Degree Of Recovery

The tolerance of 5 species of annual medics (Medicago spp.), Trifolium subterraneum cv. Nungarin, and hedge mustard (Sisymbrium orientale) to a range of post-emergence broadleaf herbicides was tested over 2 years. The least damaging to M. truncatula was 2,4-DB, which provided more consistent and effective control of hedge mustard than the other chemicals tested, including the less expensive tank mix of 2,4-DB + diuron. MCPA amine or sodium salt (300 g a.i./ha), bromoxynil (420 g a.i./ha), and tank mixes containing MCPA amine (150-175 g a.i./ha) severely damaged annual medics, particularly M. truncatula, with flowering delayed by up to 21 days, and dry matter and seed yields often significantly (P<0.05) reduced. Seed yields of most test plants indicated a degree of recovery from herbicide damage assessed visually after 10 days. Hedge mustard was not always as severely damaged by MCPA amine as was M. truncatula. Nungarin subterranean clover and M. aculeata SAD 2356 were more tolerant than the M. truncatula cultivars of MCPA amine, MCPA sodium salt, MCPA tank mixes, and bromoxynil, and less tolerant of 2,4-DB. Medicago littoralis, M. polymorpha and M. laciniata were severely damaged by bromoxynil but were more tolerant of MCPA than M. truncatula.

Nitrogenase Activity by Subterranean Clover and Other Temperate Pasture Legumes

1988 ◽  
Vol 15 (5) ◽  
pp. 657 ◽  
Author(s):  
AG Davey ◽  
RJ Simpson
Keyword(s):  
Root Respiration ◽  
Nitrogenase Activity ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Acetylene Reduction Activity ◽  
Diffusion Resistance ◽  
Pasture Legumes ◽  
Reduction Activity ◽  
Decline Rate ◽  
Nodulated Root

Nitrogenase (C2H2-reduction) activity and nodulated root respiration of intact plants of subterranean clover (Trifolium subterraneum L.) cv. Seaton Park nodulated by Rhizobium trifolii WU95 were measured in a flow-through system. Simultaneous declines in nitrogenase activity and respiration were exhibited 2 min after 10% C2H2 had been introduced into the gas stream. Declines in nitrogenase activity and nodulated root respiration provided an estimate of the efficiency of nitrogenase activity (mol CO2 evolved/mol C2H4 produced). The pre-decline rate of nitrogenase activity at time zero was thus calculated as the product of the respiration associated with nitrogenase activity and the reciprocal of the efficiency of nitrogenase activity. Pre-decline rates of nitrogenase activity were similar to peak rates for several pasture legumes. However, post-decline rates of activity were as much as 70% lower than the pre-decline rate. The age of subterranean clover plants had an important influence on the magnitude of the C2H2-induced decline; young plants exhibited the largest C2H2-induced inhibition of nitrogenase activity. Neither sainfoin (Onobrychis viciifolia Scop.) cv. Othello nodulated by Rhizobium sp. CC1108 nor yellow serradella (Ornithopus compressus L.) cv. Pitman nodulated by R. lupini WU425 exhibited C2H2-induced declines in nitrogenase activity. Nitrogenase-linked respiration of subterranean clover at the 14-leaf stage accounted for 50% of total nodulated root respiration. The oxygen diffusion resistance of the nodules increased in the presence of C2H2 but the effect was reversible once C2H2 was removed from the gas atmosphere. The pre-decline rate of acetylene reduction activity of subterranean clover reached a maximum at 10% C2H2. The C2H2-induced decline in nitrogenase activity was lower at subsaturating pC2H2 and was not detected at 0.4% C2H2.

Virus diseases of annual pasture legumes: incidences, losses, epidemiology, and management

2012 ◽  
Vol 63 (5) ◽  
pp. 399 ◽  
Author(s):  
Roger A. C. Jones
Keyword(s):  
Large Scale ◽  
Current Knowledge ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Virus Diseases ◽  
Pasture Legumes ◽  
Improvement Programs ◽  
Annual Medics ◽  
Grazed Swards ◽  
Pasture Legume

This paper reviews current knowledge concerning the occurrence, losses caused, epidemiology, and management of virus diseases of annual pasture legumes. The viruses commonly present are spread by contact, or aphid vectors either non-persistently or persistently. Whether they are seed-borne and their means of transmission are critical factors determining their incidences within pastures in climatic zones with dry summers or substantial summer rainfall. Large-scale national or state surveys of subterranean clover pastures revealed that some viruses reach high infection incidences. Contamination with seed-borne viruses was widespread in plots belonging to annual pasture legume improvement programs and seed stocks of subterranean clover, annual medics, and alternative annual pasture legumes, and in commercial annual medic seed stocks. Yield loss studies with grazed swards were completed for three common viruses: two in subterranean clover and one in annual medics. These studies demonstrated considerable virus-induced losses in herbage and seed yields, and established that virus infection causes deteriorated pastures with high weed contents even when foliar symptoms are mild. Comprehensive integrated disease management tactics involving phytosanitary, cultural, chemical, or host resistance measures were devised for these three viruses in infected pastures, and for seed-borne viruses in annual pasture legume improvement programs. Several other viruses are potentially important, but, with these, quantification of losses caused in grazed swards is lacking and information on incidences in pastures is currently insufficient. Critical research and development gaps that need addressing are identified.

Long-term patterns of seed softening in some annual pasture legumes in a low rainfall environment

1992 ◽  
Vol 32 (3) ◽  
pp. 331 ◽  
Author(s):  
GB Taylor ◽  
MA Ewing
Keyword(s):  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Medicago Polymorpha ◽  
Pasture Legumes ◽  
Burr Medic ◽  
Growing Environment ◽  
Simulated Field ◽  
Favourable Environment

Annual rates of seed softening were determined from 4 lines of burr medic (Medicago polymorpha), 1 barrel medic (M. truncatula), and 1 subterranean clover (Trifolium subterraneum) grown at Merredin in the 1 year. Measurements were also made on one of the lines of burr medic grown in 2 other environments, Gnowangerup and Eneabba, in the same year. Burrs were placed on the soil surface at Merredin and the numbers of residual hard seeds determined each year for up to 5 years in this one environment. Patterns of softening of seeds from the same seed populations were also determined in a laboratory oven with a diurnal temperature fluctuation of 60/15�C. In the field, the softening rates of the 5 medics grown at Merredin were similar, averaging 21% of the original seeds each year for the first 4 years. Seeds of the burr medic grown in a more favourable environment at Eneabba were much slower to soften (averaging 14%); hence, hardseededness in these medics was influenced more by the growing environment than by genotype. More than half of the seeds of subterranean clover softened in the field over the first summer, with declining annual proportions thereafter. There were clear differences between the clover and medics in both pattern and rate of seed softening. The lower seed-softening rate of medics than of subterranean clover was more favourable for ley systems involving frequent cropping, especially in low rainfall areas. Treatment of seeds at 60/15�C simulated field softening for subterranean clover well but produced misleading results for the medics.

Seedling emergence and survival of annual pasture legumes in northern New South Wales

1996 ◽  
Vol 47 (4) ◽  
pp. 559 ◽  
Author(s):  
GM Lodge
Keyword(s):  
New South ◽  
Seedling Emergence ◽  
New South Wales ◽  
Survival Rates ◽  
Trifolium Subterraneum ◽  
Survival Curves ◽  
Vicia Villosa ◽  
Pasture Legumes ◽  
South Wales ◽  
Seedling Emergence And Survival

Seedling emergence and survival of 15 annual pasture legumes was studied in the field at Tamworth, northern New South Wales. Emergence was measured in permanent quadrats (0.09 m2) in covered and uncovered areas approximately every 15 days from 30 November 1983 to 30 November 1984. Survival of seedlings was estimated from 15 December 1983 to 31 August 1984, before plants senesced. Emergence was generally highest in summer and autumn following seed set and lowest in winter and spring. Two legumes, Medicago scutellata cv. Sava and Trifolium subterraneum cv. Seaton Park, had high emergence in winter (mid July). Total seedling emergence was highest ( P < 0.05) in covered areas of cv. Seaton Park and uncovered areas of T. hirtum cv. Hykon. All T. subterraneum cultivars, M. minima, Astragalus hamosus cv. Ioman, Vicia villosa cv. Namoi, and M. truncatula cv. Paraggio had higher total emergence in covered compared with uncovered areas. In contrast, total emergence of M. aculeata, M. truncatula cv. Jemalong, Sava, and Hykon was lowest in covered areas. Cover had little effect on the total emergence of M. truncatula cv. Sephi and T. glomeratum. Of the 7700 individual seedlings marked from November 1983 to August 1984, a mean of only 31% (covered) and 41% (uncovered) survived until 31 August 1984. For each emergence time, highest ( P < 0.05) survival rate coincided with the highest (P < 0.05) number of emerged seedlings in 4 of the legumes in covered areas (cv. Namoi, 31 January; cv. Ioman, 31 March; cv. Hykon, 15 April; cv. Sava, 15 July; Table 4) and 9 in uncovered areas (cvv. Nungarin, Seaton Park, and Namoi, 31 January; M. aculeata and cv. Sephi, 28 February; cvv. Jemalong and Ioman, 31 March; T. glomeratum, 15 April; cv. Sava, 15 July). In all other legumes there was no optimum time for emergence, since the highest (P < 0.05) survival rates were associated with seedling survivals <50%. Generally, survival curves with a mortality constant rather than a mortality rate were a better fit ( P < 0.05) for most legumes and times. This implied that these survival curves were determined at the time of recruitment, and declined at a constant rate, despite below-average post-emergence rainfall in May-June. Low rates of survival at times of highest ( P < 0.05) emergence indicated that there may have been some density-dependent regulation in some of the legumes.

Effect of depth of burial on the longevity of hard seeds of subterranean clover and annual medics

1988 ◽  
Vol 28 (1) ◽  
pp. 77 ◽  
Author(s):  
GB Taylor ◽  
MA Ewing
Keyword(s):  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Barrel Medic ◽  
Hard Seeds ◽  
Burr Medic ◽  
Seed Reserves ◽  
Annual Medics ◽  
Depth Of Burial ◽  
Tillage Operations

Burrs of 3 cultivars of subterranean clover (Trifolium subterraneum) and 1 cultivar each of burr medic (Medicago polymorpha) and barrel medic (M. truncatula), which had experienced 1 summer at the soil surface, were placed on the soil surface and at depths of 2, 6 and 10 cm in the soil. The numbers of residual hard seeds were determined each year for up to 4 years. There was a marked reduction in the rate of seed softening in all 3 clover cultivars with increasing depth of burial. Whereas <20% of the seeds of the hardest seeded clover cultivar, Nungarin, survived 3 years at the soil surface, there was no significant decline in seed numbers during 4 years of burial at 10 cm. Even with cv. Geraldton, in which only 5% of seeds remained after 1 year of placement at the soil surface, 75% of seeds survived 4 years of burial at 10 cm. Hard seeds of both medic varieties were considerably more resilient than clover seeds at the soil surface, particularly during the first summer following seed set. However, burial had much less effect on their longevity, with no significant effect of burial to 2 cm in either medic, or of burial to 6 cm in the case of barrel medic. These results support earlier findings which showed that tillage operations associated with crop establishment which result in the burial of substantial proportions of subterranean clover seeds can lead to useful soil seed reserves. The much lesser effect of burial on seed softening of the medics, compared with subterranean clover, suggests that tillage operations will be less advantageous to medic persistence in leys.

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