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.

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.

Comparative phosphate requirements of yellow serradella (Ornithopus compressus) burr medic (Medicago polymorpha var. brevispina) and subterranean clover (Trifolium subterraneum)

1990 ◽  
Vol 30 (4) ◽  
pp. 507 ◽  
Author(s):  
BH Paynter
Keyword(s):  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Medicago Polymorpha ◽  
P Content ◽  
Shoot Production ◽  
Ornithopus Compressus ◽  
Burr Medic ◽  
Total Plant ◽  
Greater Curvature ◽  
Total Seed

The phosphate (P) requirements of burr medic (Medicago polymorpha) on marginally acidic, medium-textured soils and yellow serradella (Ornithopus compressus) on acidic, light-textured soils in the low rainfall (<400 mm) wheatbelt of Western Australia are not known. The hypothesis that yellow serradella, subterranean clover (Trifolium suhrerraneum) and burr medic have the same external requirement for applied P was tested in a glasshouse trial on 2 P-deficient soils. Species were compared on an equal total seed weight and similar maturity length basis. It was found that yellow serradella required less soil applied P to achieve 90% maximum shoot production or total plant (shoots + roots) growth and had a greater curvature co-efficient from fitted Mitscherlich functions than either subterranean clover or burr medic. Burr medic was the most responsive to applied P and had the largest external requirement for applied P. These differences in external P requirements were related to differences in ability of the 3 legumes to absorb P and to transport it to their shoots and were not due to differences in internal efficiency of the shoots. Yellow serradella was able to take up more P (total plant P content) per g roots than subterranean clover, and subterranean clover more than burr medic. The same relationship applied to the translocation of absorbed P from roots to shoots.

Evaluation of annual pasture legumes in northern New South Wales. 2. Trifolium and Medicago spp. and other legumes

2007 ◽  
Vol 47 (5) ◽  
pp. 563 ◽  
Author(s):  
G. M. Lodge ◽  
S. Harden
Keyword(s):  
New South ◽  
New South Wales ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Smoothing Splines ◽  
Limited Data ◽  
Pasture Legumes ◽  
South Wales ◽  
Annual Medicago

Two studies to evaluate annual pasture legumes were sown in replicated plots near Tamworth, New South Wales. In the first (experiment 1), 24 entries were sown in 1995 and in a second study (experiment 2) 33 entries were sown in 1996. Green herbage mass (kg DM/ha) was assessed in the year of sowing (spring) and thereafter four times per year until spring 2000. Limited data were also collected to estimate maturity grading, seed yield and seedling regeneration. For each experiment, green herbage mass data were examined using cubic smoothing splines and at the end of each study, green herbage mass values predicted from the model were used to assess the significance (P = 0.05) of differences between cultivars or lines. In spring 2000 (experiment 1), Trifolium subterraneum var. brachycalycinum cv. Clare had the highest rank of the cultivars and lines, and T. michelianum cv. Paradana the lowest (previously cultivated site). For the native pasture site, CPI 70056B subterranean clover had the highest rank and Ornithopus compressus cv. Paros the lowest. In experiment 2, Clare had the highest rank in spring 2000 and T. resupinatum cv. Bolta had the lowest ranking. Long-term green herbage mass appeared to be strongly influenced by maturity grading, but other factors may have affected the performance of annual Medicago spp., O. compressus, T. resupinatum, and T. michelianum. Results from the current study and previous reported research indicated that T. subterraneum var. subterraneum cvv. York (evaluated as CPI 89846B) and Junee and T. subterraneum var. brachycalycinum cv. Clare performed best in northern New South Wales.

Effects of extended (4-12 years) burial on seed softening in subterranean clover and annual medics

1996 ◽  
Vol 36 (2) ◽  
pp. 145 ◽  
Author(s):  
GB Taylor ◽  
MA Ewing
Keyword(s):  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Razor Blade ◽  
Barrel Medic ◽  
Hard Seeds ◽  
Soil Temperatures ◽  
Burr Medic ◽  
Annual Medics ◽  
Softening Process

The effect of burial of seeds of 3 cultivars of subterranean clover (Trifolium subterraneum) and 1 cultivar each of burr medic (Medicago polymorpha) and barrel medic (M. truncatula) that had experienced 1 summer at the soil surface was continued from 4 to up to 12 years. Seeds were situated at 2, 6 and 10 cm depth, as well as at the soil surface. Numbers of residual seeds were determined after each sampling occasion, the timing of which was varied between cultivars and depths of burial according to the progress of seed softening. The marked reduction in the rate of seed softening in all 3 clover cultivars with increasing depth of burial established during the first 4 years of the experiment was maintained. After 12 years, 37% of the Nungarin clover seeds that had been buried at 10 cm were still present as hard seeds. All residual hard seeds germinated readily after nicking with a razor blade. Seeds of both medic cultivars, that were slower to soften than the clovers at the soil surface, continued to show little effect of burial at 2 cm, or of burial to 6 cm in the case of Cyprus barrel medic. Species differences in response to seed burial are explained in terms of the effects of soil temperatures on the 2-stage seed softening process. The absence of an effect of shallow burial on the softening of medic seeds appears to be attributable to a lower optimum temperature for the first stage of seed softening than is the case for subterranean clover. Unfavourable temperatures for the final stage of seed softening can result in the accumulation of latent soft seeds, particularly in subterranean clover. These latent soft seeds will soften during the first summer/autumn after their return to close to the soil surface as a consequence of tillage. Whereas increased seed longevity as a consequence of burial in crop years can be advantageous in terms of legume persistence, particularly of clover, it can also be distinctly disadvantageous when it comes to cultivar replacement.

Response of defoliated swards of subterranean clover and yellow serradella to superphosphate applications

1991 ◽  
Vol 31 (6) ◽  
pp. 777
Author(s):  
MDA Bolland
Keyword(s):  
Field Experiment ◽  
Sandy Soil ◽  
Dry Matter ◽  
Maximum Yield ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Herbage Yield ◽  
Ornithopus Compressus ◽  
The Relationship

The effect of superphosphate applications (0, 25, 50, 75, 100 and 125 kg P/ha to the soil surface) on the dry matter (DM) herbage production of dense swards of subterranean clover (Trifolium subterraneum cv. Junee) and yellow serradella (Ornithopus compressus cv. Tauro) was measured in a field experiment on deep, sandy soil in south-western Australia. The swards were defoliated with a reel mower at weekly intervals from 88 to 158 days after sowing, to a height of 2 cm for the first 9 cuts, 4 cm for the tenth cut and 5 cm for the eleventh cut. Yellow serradella was more productive than subterranean clover. Consequently, for the relationship between yield and the level of phosphorus (P) applied, yellow serradella supported larger maximum yields and required less P than subterranean clover, to produce the same DM herbage yield. Maximum yields of yellow serradella were 12-40% larger. To produce 70% of the maximum yield for yellow serradella at each harvest, yellow serradella required about 50% less P than subterranean clover. However, when yields were expressed as a percentage of the maximum yield measured for each species at each harvest, the relationship between yield and the level of P applied was similar for both species, and they had similar P requirements.

Effect of perennial pasture species on surface soil moisture and early growth and survival of subterranean clover (Trifolium subterraneum L.) seedlings

1997 ◽  
Vol 48 (5) ◽  
pp. 683 ◽  
Author(s):  
B. S. Dear ◽  
P. S. Cocks
Keyword(s):  
Mineral Soil ◽  
Subterranean Clover ◽  
Late Summer ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Annual Grass ◽  
Growth And Survival ◽  
Eastern Australia ◽  
Standing Dead ◽  
Clover Seed

Subterranean clover seedling numbers and growth in swards containing 1 of 5 perennial pasture species [phalaris (Phalaris aquatica) cv. Sirolan, cocksfoot (Dactylis glomerata) cv. Currie, lucerne (Medicago sativa) cv. Aquarius, wallaby grass (Danthonia richardsonii) cv. Taranna, and lovegrass (Eragrostis curvula) cv. Consol] were compared with those in typical annual pastures and pure clover swards in the wheatbelt of eastern Australia. Presence of a perennial species or the volunteer annual grass (Eragrostis cilianensis) increased the rate of drying of the soil surface (0–5 cm) after late February and May rain, compared with subterranean clover swards. Perennials differed in the rate they dried the soil surface, with the more summer-active lucerne and consul lovegrass drying the profile more rapidly than phalaris. The amount of water in the surface 5 cm, 6 days after the rainfall event on 27–28 February, was strongly negatively correlated (r = –0·75, P < 0·01) with the amount of green perennial biomass, but not related to standing dead material or surface residues. Where perennials were present, a smaller proportion (2–4%) of the clover seed pool produced seedlings in response to late summer rain, compared with pure clover swards (18%). A higher proportion of the seed pool produced seedlings (19–36%) following rain in late autumn but there was no difference between species. The more summer-active perennials (cocksfoot, danthonia, and lucerne) markedly depressed the survival of emerged clover seedlings following both germinations. Of the seedlings that emerged in early March, the proportion remaining by 29 March was 57% in phalaris, 21% in lucerne, 13% in danthonia, and 1% in cocksfoot, compared with a 78% increase in seedlings in pure subterranean clover swards. By 15 May, all perennials had <2 clover seedlings/m2 surviving, compared with 37 in the annual pasture and 964 plants/m2 in pure subterranean clover. Following the May germination, the highest proportion of emerged seedlings surviving until 29 May was in the phalaris swards (40%) and least in the cocksfoot and danthonia swards (2–4%). Presence of a perennial or annual grass decreased (P < 0·05) relative water content of clover seedlings on 15 March from 74% in pure clover swards, to 48% in annual pasture, 34% in phalaris, and 29% in lucerne swards. Clover seedlings growing in pure subterranean swards on 15 March (17 days after germinating rain) were 4 times larger than those in lucerne and twice as large as those in either phalaris or annual pasture. Seed size did not differ between treatments, but available mineral soil nitrogen was significantly higher (P < 0·001) in pure subterranean clover swards (32 mg N/g) compared with perennials (3–13 mg N/g). Strategies such as heavy grazing in late summer to reduce green biomass of the perennials or sowing the perennials at lower densities may reduce the adverse effects that perennials have on subterranean clover seedlings in these drier environments.

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.

Manganese toxicity in Trifolium balansae, T. resupinatum, T. subterraneum, Medicago murex, M. polymorpha, M. sativa, Lotus pedunculatus, and Ornithopus compressus: relative tolerance and critical toxicity concentrations

1995 ◽  
Vol 35 (3) ◽  
pp. 367 ◽  
Author(s):  
DGDe Marco ◽  
CB Li ◽  
PJ Randall ◽  
Marco DG De
Keyword(s):  
Triticum Aestivum ◽  
Subterranean Clover ◽  
Pasture Legumes ◽  
Relative Tolerance ◽  
Ornithopus Compressus ◽  
Burr Medic ◽  
Lotus Pedunculatus ◽  
Persian Clover ◽  
High Concentrations ◽  
Mn Concentrations

This paper describes the tolerance to high concentrations of manganese (Mn) of pasture legumes that are suitable for the >500 mm rainfall zone in southern Australia. The legumes are lucerne (Medicago sativa), burr medic (M. polymorpha), murex medic (M. murex), balansa clover (Trifolium balansae), Persian clover (T. resupinatum), subterranean clover (T: subterraneum), greater lotus (Lotus pedunculatus), and seradella (Ornithopus compressus). Wheat (Triticum aestivum) cv. Egret and subterranean clover cvv. Mt Barker and Karridale were included to place the tolerance of the remaining species in the context of other studies.Symptoms of toxicity differed between species. Species ranking (in descending order) for Mn tolerance, and external threshold Mn concentrations (mmol/L), were subterranean clover (1.0), wheat (0.71), balansa clover (0.54), greater lotus (0.51), serradella (0.50), Persian clover (0.25), murex medic (0.24), burr medic (0.20), and lucerne (0.19). Critical toxicity concentrations derived from the relationships of yields to Mn concentrations in whole shoots for each species were as follows (mg Mn/kg DW): subterranean clover (2010), balansa clover (1330), serradella (1080), greater lotus (760), wheat (570), burr medic (440), murex medic (430), Persian clover (360), lucerne (190).

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.

A Method for obtaining Samples of the Population of Collembola (Symphypleona) in Pastures

1933 ◽  
Vol 24 (3) ◽  
pp. 351-352 ◽  
Author(s):  
J. Davidson ◽  
D. C. Swan
Keyword(s):  
Moisture Content ◽  
Total Population ◽  
Surface Soil ◽  
Relative Proportion ◽  
Subterranean Clover ◽  
Soil Surface ◽  
Trifolium Subterraneum ◽  
Food Plants ◽  
Simple Method ◽  
Factors Affecting

In our investigations on Smynthurus viridis, L., a study has been made of the population of this species, in an area of lucerne, at intervals of three and four days throughout the season.The density of the population of the species in a favourable pasture is markedly affected by the relative abundance of certain food-plants, especially leguminous species and particularly clovers such as subterranean clover (Trifolium subterraneum) and lucerne (Medicago sativa).The activity of the insect is intimately associated with the moisture of its environment, and the moisture content of the surface soil is one of the most important factors affecting the environmental conditions.Considering the habits of the insect, it was felt that the sweeping method would not give a reliable record of the total population in a given area of pasture. A sample obtained by sweeping with a net does not include individuals on or near to the surface of the soil. The relative proportion of individuals situated on or near the soil surface and those situated further up the plants varies considerably from time to time, according to the meteorological conditions, the growth of the herbage and the moisture content of the surface soil. It was necessary therefore to devise a simple method by means of which a more accurate record of the total population in a given area could be obtained.

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