Flower initiation in pasture legumes. III. Flower initiation in Medicago tribuloides Desr. and other annual medics.

1955 ◽  
Vol 6 (2) ◽  
pp. 258 ◽  
Author(s):  
Y Aitken
Keyword(s):  
Low Temperature ◽  
Subterranean Clover ◽  
Late Summer ◽  
Flower Initiation ◽  
Commercial Variety ◽  
Barrel Medic ◽  
Pasture Legumes ◽  
Annual Medics ◽  
Long Photoperiod

Observations on barrel medic (Medicago tribuloides Desr., commercial variety) sown throughout the year in the field showed that the flower initiation of the winter sowings was the most rapid and that of the late summer sowings the most delayed. This delay was due to the absence of sufficiently low temperature following germination. Low temperature and long photoperiod accelerate flower initiation in barrel medic as in subterranean clover. Five types of annual medic that persist under Mallee conditions are similar in their flower initiation character to that of the "second-early" varieties of subterranean clover.

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.

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.

Flower initiation in pasture legumes. IV. Flower initiation in Trifolium pratense L.

1964 ◽  
Vol 15 (1) ◽  
pp. 21 ◽  
Author(s):  
Y Aitiken
Keyword(s):  
Trifolium Pratense ◽  
Continuous Light ◽  
Red Clover ◽  
Flower Initiation ◽  
Pasture Legumes ◽  
Flowering Season ◽  
Short Period ◽  
Trifolium Pratense L ◽  
Long Photoperiod ◽  
Early Strain

An early strain (Cowgrass) and a late-maturing strain (Montgomery) of red clover (Trifolium pratense L.) were grown at Melbourne, lat. 38°S., to study flower initiation and the relationship between initiation and flowering, because of the importance of flowering to the use of the species as a source of hay. The terminal inflorescence in red clover arises from a lateral bulge at the shoot apex, and the main shoot of the plant is strongly vegetative, only becoming reproductive in a proportion of plants under long photoperiod, particularly continuous light. In both strains, whether first-year or older plants, flower initiation and therefore flowering were confined to a short period of the year, the early strain having the longer period. Sowing the two strains at intervals through the year in the field, under natural and long photoperiods, showed the importance of both photoperiod and temperature to initiation. Both strains were hastened by a long photoperiod whatever the temperature, and initiated at a similar low leaf number, but the early strain was able to initiate at a shorter photoperiod than the late one. Seed vernalization had almost no effect; but at photoperiods of 14 to 11 hr, high temperatures strongly retarded Cowgrass and appeared to prevent initiation in Montgomery. The capacity of Cowgrass to initiate at a shorter photoperiod and at higher temperatures than Montgomery explains its longer flowering season in temperate latitudes. These genetic differences suggest that an appropriate environment can be used to differentiate early and late-flowering strains for seed certification, and that late strains would stay vegetative at low latitudes and would therefore be less useful as a source of hay than early ones.

Wether bioassay of annual pasture legumes. III. The oestrogenic potency of dry subterranean clover pastures, and of leaf blade and petiole in the green state

1965 ◽  
Vol 16 (1) ◽  
pp. 23 ◽  
Author(s):  
CM Francis ◽  
AJ Millington
Keyword(s):  
Leaf Blade ◽  
Subterranean Clover ◽  
Late Summer ◽  
Green Leaf ◽  
Green State ◽  
Pasture Legumes ◽  
Measurable Activity

Late summer pastures of nine strains of subterranean clover had very low oestrogenic activity as assessed by wether teat length bioassay. Only the Dwalganup variety had measurable activity which may have been due mainly to moderate levels of coumestrol in the various dry plant fractions. The activity of green leaf blade of the Yarloop strain was about nine times as great as that of the petioles. Possible agronomic implications of this finding are discussed.

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.

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).

Flower initiation in relation to maturity in crop plants. I. Flower initiation in relation to maturity in some Australian oats (Avena spp.)

1961 ◽  
Vol 12 (3) ◽  
pp. 371 ◽  
Author(s):  
Y Aitken
Keyword(s):  
High Temperatures ◽  
Low Temperatures ◽  
Subterranean Clover ◽  
Late Summer ◽  
Crop Plants ◽  
Leaf Number ◽  
Flower Initiation ◽  
Early Group ◽  
Wide Range ◽  
Cold Requirement

The description of oat varieties as early, mid, and late depends mainly on differences in their time of flower initiation. Flower initiation has been studied in varieties grown in southern Australia and ranging in maturity from first early to late. The time to flower initiation was found to depend greatly on the variety�s response to photoperiod and temperature. In all groups but the first early one, initiation was hastened by lengthening photoperiod and reducing temperature. The later the variety, the greater was the effect. Early varieties are those in which initiation occurs at a low leaf number over a wide range of photoperiods and temperatures. Late varieties result from initiation at a high leaf number, the delay compared with early varieties being due to sensitivity to high temperatures and to short photoperiods. These are the conditions prevailing after late summer and autumn sowings. Late varieties mature early in the field when grown either at low temperatures (below 50�F), or at slightly higher temperatures (below 60�F) and intermediate photoperiod. This is similar to the reaction of variety Clare in the second early group of' subterranean clover. Very late varieties of oats, similar to winter wheats which have a pronounced cold requirement for initiation, are not yet present in Australia.

Sulfur nutrition of temperate pasture species. II. A comparison of subterranean clover cultivars, medics and grasses

1984 ◽  
Vol 35 (3) ◽  
pp. 389 ◽  
Author(s):  
MA Gilbert ◽  
AD Robson
Keyword(s):  
Maximum Yield ◽  
Subterranean Clover ◽  
Nitrogen Supply ◽  
Sulfur Deficiency ◽  
Barrel Medic ◽  
Pasture Legumes ◽  
Sulfur Supply ◽  
Wimmera Ryegrass ◽  
Brome Grass ◽  
Sulfur Nutrition

The external and internal requirements for sulfur of five pasture legumes and three grasses of temperate origin were examined in a pot experiment in which plants were grown with seven levels of sulfur supply for 58 days. Nitrogen supply was non-limiting. There was no distinct difference between legumes and grasses in their external requirement for sulfur (i.e. the amount of sulfur required for 90% of maximum yield) or in their sensitivity to sulfur deficiency (i.e. yield at the lowest sulfur supply expressed as a percentage of maximum yield). The requirement for sulfur (mg/pot) fell in the following order: Hunter River lucerne (24) > Jemalong barrel medic (19) > brome grass and Wimmera ryegrass (18) > barley grass (15) > Clare subterranean clover (13) > Trikkala subterranean clover (11) > Seaton Park subterranean clover (10). The high external requirement for sulfur of Hunter River lucerne appears to be due to its poor ability to distribute sulfur from root to shoot and to its high internal requirement for sulfur. However, for Jemalong barrel medic, the high external requirement was solely due to its high internal requirement for sulfur. The higher external requirement for sulfur of the grasses compared with the subterranean clover cultivars appears to be due to the poorer ability of the grasses to obtain sulfur from the soil used in this experiment, rather than to differences in the transfer of sulfur from root to shoot, or in their internal requirement for sulfur.

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.

Time distribution of seedlings emergence from single seed crops of several annual pasture legumes

1972 ◽  
Vol 12 (59) ◽  
pp. 628 ◽  
Author(s):  
GB Taylor
Keyword(s):  
Seed Set ◽  
Seedling Emergence ◽  
Subterranean Clover ◽  
Hard Seed ◽  
Barrel Medic ◽  
The Third ◽  
Single Seed ◽  
Pasture Legumes ◽  
Original Seed ◽  
Seed Crops

Seedling emergence from single seed crops of Dwalganup and Geraldton subterranean clover, Yamina cupped clover, Troodos and Kondinin rose clover, and Cyprus barrel medic, was studied in a low rainfall wheatbelt environment in Western Australia. The proportion of the original seed set recovered as seedlings was highest from the subterranean clovers in the first year but about the same for all genotypes in the second year. Few subterranean clover seeds were recovered in the third regeneration year either as seedlings or residual hard seeds, whereas significant proportions of the original seed of the other genotypes were obtained. More than 10 per cent of the original seed of Cyprus barrel medic and Yamina cupped clover remained ungerminated at the end of the third season. Between about 35 and 75 per cent of the original seed set was not accounted for in the genotypes studied. The proportions of the total seedling numbers that emerged following summer and early autumn rains were generally highest from the subterranean clovers and least from the cupped clover and medic. It is suggested that these different patterns of emergence within years were the result of differences in embyro dormancy rather than different patterns of hard seed breakdown.

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