Effects of irrigation timing in autumn and spring on seed production of subterranean clover, and the change in permeability and rate of germination of seed

1987 ◽  
Vol 27 (6) ◽  
pp. 799 ◽  
Author(s):  
KB Kelly ◽  
WK Mason
Keyword(s):  
Seed Production ◽  
Subterranean Clover ◽  
Late Summer ◽  
Summer Rainfall ◽  
Late Winter ◽  
Germination Test ◽  
Seed Burial ◽  
Feed Production ◽  
Large Influence ◽  
Number Of Seeds

The effects of time of initial irrigation in late summer-autumn and final irrigation in spring on the amount of seed present, seed burial, relative proportions of each cultivar and changes in seed permeability with time were studied in mixed cultivar swards (cvv. Clare, Woogenellup and Trikkala) of subterranean clover. Irrigation treatments were 3 times of initial irrigation (1 February, 1 March and 1 April) combined with 2 times of final irrigation (mid October and mid November) from 1982 to the autumn of 1985. Seed was sampled 3 times per year; in mid December, prior to initial irrigation and in late winter. The timing of the first irrigation in autumn had no effect on the number of seed present in December which averaged 55,57 and 78 seeds/dm2 in 1982, 1983 and 1984 respectively. Time of final irrigation in spring had a large influence on the number of seeds present in mid December, with a 3-year average of 42 seeds/dm2 for the mid October treatment and 85 seeds/dm2 for the mid November treatment. Rainfall in summer and early autumn reduced the number of seed present between December and the initial irrigation. Residual seed measured in late winter accounted for 18% of the seed present in the previous December and was mostly located below the ground. Without summer rainfall, the proportion of permeable seed averaged over all cultivars increased from approximately 20% in mid December to 40, 60 and 70% in February, March and April respectively. The rate of germination of permeable seed was influenced by time of sampling, temperature of germination test (15 and 30�C), the incidence of rainfall, and the type of cultivar. The limitations of current subterranean clover cultivars under irrigated conditions are discussed and an outline of the characteristics required by cultivars to be used under irrigation is presented, with particular reference to autumn feed production.

Availability to grazing sheep of gastrointestinal nematode infection arising from summer contamination of pastures

1978 ◽  
Vol 29 (1) ◽  
pp. 189 ◽  
Author(s):  
AD Donald ◽  
FHW Morley ◽  
PJ Waller ◽  
A Axelsen ◽  
JR Donnelly
Keyword(s):  
Haemonchus Contortus ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Gastrointestinal Nematode ◽  
Infected Sheep ◽  
Grazing Management ◽  
Late Winter ◽  
Nematode Eggs ◽  
Autumn And Winter ◽  
Clover Pasture

In two successive years, separate phalaris-subterranean clover pasture plots near Canberra were contaminated with nematode eggs by grazing with naturally infected sheep in each of the summer months (December, January, February) and the first month of autumn (March). At intervals until mid- to late winter, the availability of infection on pasture was estimated by grazing with worm-free 'tracer' lambs which were subsequently slaughtered for worm counts. Summer rainfall in both years was above average. Tracer counts of Haemonchus contortus and Ostertagia, Trichostrongylus and Nematodirus spp. per l08 eggs per hectare remained high during summer, with evidence that migration of larvae to the herbage could continue for at least 2 months after contamination. Rates of decline in tracer worm counts over the autumn and winter did not differ between years, and from an assumed maximum 2 months after contamination in each of the summer months, were fastest from December and slowest from February contamination. These rates were similar for all genera on December-contaminated plots, but on January and February plots, Ostertagia spp. declined more slowly. H. contortus numbers fell sharply in early autumn to be low by the end of May. By mid July there would be few larvae of all genera available on pastures contaminated in December and January, but this is less certain on February-contaminated pastures, especially for Ostertagia spp. Implications for the control of nematode infections in sheep by anthelmintic treatment and grazing management are considered.

Seasonal trends and variability of soil moisture under temperate pasture on the Northern Tablelands of New South Wales

1975 ◽  
Vol 15 (73) ◽  
pp. 250 ◽  
Author(s):  
RCG Smith ◽  
GG Johns
Keyword(s):  
Soil Moisture ◽  
Field Experiments ◽  
New South ◽  
New South Wales ◽  
Late Summer ◽  
Summer Rainfall ◽  
Balance Model ◽  
Late Winter ◽  
Pan Evaporation ◽  
South Wales

A water balance model predicting changes in soil moisture under temperate pasture at Armidale, New South Wales was developed and tested against soil moisture measurements made from 1967 to 1969. The model accounted for 96 per cent of the variance in observed soil moisture. The model was then used to predict the expected pattern of soil moisture for this area using daily Armidale rainfall data from 1878 to 1973 and pan evaporation data from 1951 to 1970. Expected soil moisture levels rise to a maximum in late winter and then progressively decline to a minimum in mid summer. Levels may increase again slightly during late summer but remain low through autumn before beginning to rise again during winter. On the basis of this analysis it is suggested that the safest time to establish new plant species into temperate pasture is probably early winter when expected soil moisture begins to rise rapidly. Because of the autumn deficiency in soil moisture it was concluded that fodder oats grown in this period would often be inhibited by a lack of soil moisture unless preceded by a fallow to conserve late summer rainfall. The need for soil moisture data in interpreting and extrapolating from field experiments is stressed.

scholarly journals Integrated management of vulpia in dryland perennial pastures of southern Australia

2009 ◽  
Vol 60 (1) ◽  
pp. 32 ◽  
Author(s):  
K. N. Tozer ◽  
D. F. Chapman ◽  
P. E. Quigley ◽  
P. M. Dowling ◽  
R. D. Cousens ◽  
...  
Keyword(s):  
Seed Production ◽  
Integrated Management ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Summer Rainfall ◽  
Annual Rainfall ◽  
Herbicide Application ◽  
South Wales ◽  
Fertiliser Application ◽  
Western Victoria

Vulpia (Vulpia species C.C. Gmel.) are annual grass weeds that can reduce pasture quality and stock-carrying capacity of perennial pastures throughout southern Australia. To develop more effective strategies to control vulpia, an experiment was established in western Victoria (average annual rainfall 565 mm) in phalaris (Phalaris aquatica L.) pastures comparing the effects of control methods [comprising combinations of fertiliser addition (Fert), a single herbicide (simazine) application (Sim), and pasture rest from grazing (Rest)] on vulpia populations. A further herbicide treatment [paraquat-diquat (SpraySeed®)] was imposed on some of these treatments. Measurements included botanical composition, phalaris and vulpia tiller density, seed production, and number of residual seeds in the soil. Vulpia content remained unchanged in the Sim-Rest treatment but increased in all other management treatments over the duration of the 3 year study and especially where paraquat-diquat was applied, despite paraquat-diquat causing an initial reduction in vulpia content. Vulpia content was lowest in the Fert-Sim-Rest treatment. The Fert-Sim treatment and in some cases paraquat-diquat application reduced vulpia tiller production. Vulpia seed production and the residual seed population were not influenced by any of the management treatments, while the single paraquat-diquat application increased vulpia seed production 18 months after application. Phalaris content was enhanced by the Sim-Rest and Fert-Sim-Rest treatments and initially by paraquat-diquat. No treatment affected phalaris tiller production and basal cover. The subterranean clover (Trifolium subterraneum L.) content declined during the experiment, but to a lesser extent where paraquat-diquat was applied. Volunteer species content was initially suppressed in the year following paraquat-application, although populations recovered after this time. Of the two Vulpia spp. present (V. bromoides (L.) S.F. Gray and V. myuros (L.) C.C. Gmelin), V. bromoides was the most prevalent. Results show how a double herbicide application can increase vulpia fecundity and rate of re-infestation of herbicide-treated sites. Pasture rest shows some promise, but to a lesser extent than in the New South Wales tablelands, where summer rainfall may increase the growth of perennial species. In lower rainfall, summer dry areas, responses to pasture rest may be slower. Despite this, integrated management (which combines strategies such as pasture rest, herbicide application, and fertiliser application) increases the perennial content and reduces vulpia seed production, thus improving vulpia control.

The production and life span of seed of subterranean clover (Trifolium subterraneum L.)

1959 ◽  
Vol 10 (6) ◽  
pp. 771 ◽  
Author(s):  
CM Donald
Keyword(s):  
Seed Production ◽  
Genetic Difference ◽  
Seasonal Pattern ◽  
Subterranean Clover ◽  
Late Summer ◽  
Trifolium Subterraneum ◽  
Daily Minimum Temperature ◽  
South Wales ◽  
Eastern Australia ◽  
Carry Over

At an elevation of 2040 ft on the southern tablelands of Kew South Wales, seed production by swards of subterranean clover was apparently governed by mininnnn temperatures (frequency and intensity of frosts) during the flowering period. The aggregate deficit of the daily minimum temperature below 40°F in the 21 days from the commencement of flowering showed a high correlation with seed production per unit area in four successive seasons. Spring frosts account for the altitudinal limit of about 4000 ft to which subterranean clover grows in the alps of south-eastern Australia. Lateness of flowering has specific survival value at high altitudes in this region and in such areas as the high parts of the plateau of Spain. On the average 92 per cent. of the seed crop germinated in the year following its production, with 6.3 per cent. in the second year, and with falling values to 0.07 per cent. in the fifth year. Germination thereafter was nil or negligible. The early-flowering variety Dwalganup appeared to show a genetic difference in the persistence of more of its seed into the second and subsequent years. There was a regular seasonal pattern of seed germination, with the peak of germination occurring in the late summer and autumn. The "carry over" of seed into the second and subsequent years, and the germination peak in the autumn, have each considerable ecological significance.

Seasonal pasture contamination and availability of nematodes for grazing sheep

1976 ◽  
Vol 27 (2) ◽  
pp. 277 ◽  
Author(s):  
WH Southcott ◽  
GW Major ◽  
IA Barger
Keyword(s):  
Larval Stage ◽  
Late Summer ◽  
Summer Rainfall ◽  
Gastrointestinal Nematodes ◽  
Early Spring ◽  
Late Winter ◽  
Maximum Inhibition ◽  
Fourth Larval Stage ◽  
Grazing Sheep ◽  
And Control

In December 1970 and in January, February, March, April, May and September 1971 separate plots of sown pasture, each 0.1 ha, were contaminated by grazing sheep infected with gastrointestinal nematodes. In succeeding months each plot was grazed by worm-free tracer lambs for 2 weeks; the lambs were then withdrawn and held for 2 weeks in pens before slaughter for total differential worm counts. Observations on each plot continued for 12 months; the numbers of worms found in the tracer lambs indicated the seasonal occurrence of nematode larvae on pasture. For Haemonchus contortus, larval availability from deposition was rapid in summer and slow in autumn, maximum inhibition at the fourth larval stage occurring in larvae picked up in the winter months. Ostertagia spp. presented a marked contrast, with curtailed development in summer and contamination in autumn producing high levels of infection on pasture in late winter and early spring when inhibition was at maximum levels. Of the other species studied, intestinal Trichostrongylus spp, showed a similar pattern of development to H. contortus in summer, but as with Ostertagia spp. autumn contamination could produce infection peaks in late winter and spring. Inhibition at the fourth larval stage was not a characteristic of intestinal Trichostrongylus spp. For T. axei autumn and winter conditions favoured development, and peak infestations occurred in spring and coincided with maximum inhibition. Nematodirus spp. developed mainly in summer and most inhibition occurred at this time. Spring (September) contamination with Nematodirus spp. did not result in detectable levels of infection. For all other species spring contamination was rapidly translated to pasture and the infection was comparatively short-lived. All species were capable of overwintering on pasture and with the possible exception of T. axei a persistence of infection of at least 12 months was demonstrated. For Ostertagia spp. the importance of late summer and autumn contamination in its epizootiology and control in a summer rainfall region has been confirmed.

Factors affecting the productivity of irrigated annual pastures. 1. Time of first irrigation in late summer-early autumn

1986 ◽  
Vol 26 (3) ◽  
pp. 297 ◽  
Author(s):  
CR Stockdale
Keyword(s):  
Nitrogen Content ◽  
Irrigation Treatment ◽  
Subterranean Clover ◽  
Late Summer ◽  
Early Spring ◽  
The Other ◽  
Late Winter ◽  
Factors Affecting ◽  
Autumn And Winter ◽  
Clover Content

The influence of time of first irrigation (mid-February, early March, or late March) on the productivity of an annual pasture was studied for 3 years in northern Victoria. Beginning the irrigation of annual pastures in late summer instead of at the normal time of late March- April provided additional herbage in autumn and winter and did not adversely affect herbage production in late winter-early spring; up to 2.3 t/ha DM of additional herbage was obtained by mid June and 4.3 t/ha DM over the whole season. Earlier irrigation also increased the subterranean clover content of the pasture, resulting in herbage that was lower in digestibility and higher in nitrogen content than that in the other treatments. The benefit of early irrigation in increasing clover content may be offset by invasion by weeds. In this experiment, a potential weed problem in the earliest irrigation treatment appeared at the beginning of year 3.

The influence of defoliation on the components of seed yield in swards of subterranean clover (Trifolium subterranean L.)

1961 ◽  
Vol 12 (5) ◽  
pp. 821 ◽  
Author(s):  
RC Rossiter
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Unit Area ◽  
Control Level ◽  
Subterranean Clover ◽  
Supplementary Data ◽  
Promotive Effect ◽  
Grazed Swards ◽  
Practical Implications ◽  
Number Of Seeds

Six defoliation treatments were imposed on two strains of subterranean clover (Dwalganup and Yarloop) grown in dense swards. Seed yield (weight per unit area) was increased by 27% over controls by July, or July plus early September, defoliations. With progressively later defoliation, yields fell to the control level, then to 15% below it. The number of seeds per unit area showed an increase of almost 40% with early defoliation, whereas with later defoliation the numbers fell to the control level. The increase was due primarily to larger numbers of inflorescences per unit area and a greater proportion of buried burrs. Supplementary data from grazed swards confirmed the promotive effect of early defoliation on seed production. The promotive and detrimental effects of defoliation are discussed, and brief consideration is given to practical implications.

Competition between Clare and Seaton Park, and Clare and Daliak subterranean clovers in replacement series mixtures in the field.

1991 ◽  
Vol 42 (1) ◽  
pp. 161 ◽  
Author(s):  
MJ Hill ◽  
AC Gleeson
Keyword(s):  
Seed Production ◽  
New South ◽  
Production Capacity ◽  
Subterranean Clover ◽  
Summer Rainfall ◽  
Replacement Series ◽  
The Third ◽  
South Wales ◽  
Heavy Clay ◽  
Seed Reserves

Binary mixtures of Clare and Seaton Park, and Clare and Daliak subterranean clovers were grown for three years in de Wit replacement series in the field and defoliated at approximately 4-week intervals between mid-winter and the end of October. For the most part both mixtures exhibited competition for the same resources with Clare dominant, and progressively excluding the other cultivars; this exclusion was more rapid with Daliak than with Seaton Park. Seed production of both Seaton Park and Daliak was depressed in mixtures, and seed reserves were reduced to virtually zero by the third year, although significant growth and seed reserves remained in the monocultures. Seed production from Clare was much less dependent on plant population than was seed production from Seaton Park and Daliak. Variation between replicates and spatial heterogeneity of sward composition was greater in the Daliak experiment on a heavy clay than in the Seaton Park experiment on a lighter soil. In both experiments, large quantities of seed could not be accounted for in germinations and residual seed reserves-80% in 1986 and 33% in 1987. Significant seed losses may be characteristic of the ecology of subterranean clover in summer rainfall zones. The success of Clare in northern New South Wales may be due mainly to the vigour and high seed production capacity of individual plants.

Factors affecting competition between subterranean clover and a barley cover crop

1973 ◽  
Vol 13 (60) ◽  
pp. 56 ◽  
Author(s):  
AA McGowan ◽  
WA Williams
Keyword(s):  
Seed Production ◽  
Light Transmission ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Early Spring ◽  
Late Winter ◽  
Factors Affecting ◽  
Competition For Light ◽  
Clover Seed ◽  
Main Factor

Subterranean clover (Trifolium subterraneum) was sown with barley (Hordeum vulgare) in autumn under a variety of management treatments. Clover seed production was increased when barley emergence was delayed by seed treatment with CCC or paraffin wax, or by delayed sowing, when barley seeding rates were reduced, or when barley was clipped in late winter. The main factor limiting growth of the undersown clover was competition for light, especially in late winter and early spring when light transmission through the barley crop dropped below 60 per cent. Despite a dry spring, interspecific competition for moisture evidently imposed very little restriction on clover growth and seed production. Competition for nitrogen may have occurred earlier in the season.

scholarly journals Seasonal population dynamics of Octopus vulgaris in the eastern Mediterranean

2006 ◽  
Vol 63 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Stelios Katsanevakis ◽  
George Verriopoulos
Keyword(s):  
Eastern Mediterranean ◽  
Late Summer ◽  
Main Peak ◽  
Octopus Vulgaris ◽  
Late Winter ◽  
Visual Census ◽  
The Common ◽  
Specific Growth Rates ◽  
Seasonal Population ◽  
Seasonal Population Dynamics

Abstract The population density of Octopus vulgaris was measured by visual census with scuba diving in coastal areas in Greece (eastern Mediterranean). A time-variant, stage-classified, matrix population model was developed to interpret the seasonal variation of octopus stage densities and to estimate several life cycle parameters. An annual and a semi-annual periodic cycle were found in the stage densities. A main peak of benthic settlement was observed during summer and a secondary, irregular one during late autumn. Two spawning peaks were estimated, a main one during late winter–spring and a secondary one during late summer–early autumn. More than 50% of the just-settled individuals will eventually die after 3 months. Mortality rate declines, as individuals grow larger, reaches a minimum approximately 6 months after settlement, and then grows again probably because of terminal spawning. The life expectancy of recently settled individuals (<50 g) during their summer peak is approximately 5 months. The lifespan of the common octopus is estimated to be between 12 and 15 months. The octopuses' mean specific growth rates (±s.d.) in their natural environment were 1.61 ± 0.30 d−1 for 50–200 g individuals and 1.19 ± 0.31 d−1 for 200–500 g individuals.

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