The effects of moisture supply and defoliation during flowering on seed production and hardseededness of Trifolium subterraneum L

1990 ◽  
Vol 30 (4) ◽  
pp. 515 ◽  
Author(s):  
KA Archer
Keyword(s):  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Flowering Period ◽  
Viable Seed ◽  
Hard Seeds ◽  
Moisture Supply ◽  
Early Maturing ◽  
Seed Yields ◽  
Production Characteristics

The effect of length of the flowering period on seed production characteristics of 3 cultivars of subterranean clover (Trifolium subterraneum L.) was determined by varying the period of watering postflowering. The subterranean clover cvv. Nungarin, Seaton Park and Woogenellup were grown in polystyrene boxes and given 1 of 4 watering treatments: continuous (WC); until approximately 34 days after flowering commenced (WE); until Nungarin finished flowering (WN); as for WE but with watering recommenced after plants became wilted (WEL). Plants were either undefoliated or were repeatedly defoliated during flowering. Flowering in all 3 cultivars was terminated early and seed yields were reduced by WE (e.g. WC v. WE for Seaton Park, 1620 � 61 v. 320 � 61 kg/ha), but each of the cultivars was able to produce appreciable numbers of viable seed on the WE treatment, ranging from 406 � 95 seeds/dm2 for Woogenellup to 791 � 95 seeds/dm2 for Seaton Park. WEL increased seed size in all cultivars by approximately 50%, and increased seed numbers in Seaton Park to 1083 � 106 seeds/dm2. Nungarin produced most seeds on the WN treatment (1232 � 104 seeds/dm2), but approximately half of these were lost if the soil was kept moist during seed maturation. In comparison, little loss of seed was detected from Seaton Park and Woogenellup under continuous watering, possibly due to differences between cultivars ii seed dormancy and periods of exposure of maturing seeds to moisture. The development of initial hard seeds in Nungarin and undefoliated Seaton Park was adversely affected by continuous moisture. Repeated defoliation during flowering reduced seed yields in all cultivars (e.g. UD v. D for Seaton Park, 1130 � 44 v. 310 � 46 kg/ha), due to decreases in both seed numbers and size. The results indicate that choice of maturity of subterranean clover cultivars for areas with unreliable spring rainfall is not necessarily restricted to those early maturing cultivars which will always finish flowering prior to moisture restrictions.

Variation in seed softening patterns and impact of seed production environment on hardseededness in early-maturing genotypes of subterranean clover

2006 ◽  
Vol 57 (1) ◽  
pp. 65 ◽  
Author(s):  
H. C. Norman ◽  
F. P. Smith ◽  
P. G. H. Nichols ◽  
P. Si ◽  
N. W. Galwey
Keyword(s):  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Production Environment ◽  
Field Exposure ◽  
Hard Seed ◽  
Supplementary Irrigation ◽  
Hard Seeds ◽  
Early Maturing

This paper describes variation in the dynamics of seed softening (loss of impermeability) in 20 early-maturing genotypes, including 6 cultivars, of subterranean clover (Trifolium subterraneum L.). It reports the effect of 3 sites of seed production in south-western Australia on the pattern of softening in the first summer–autumn and on total softening over the subsequent 2 years. Seeds were softened at a single field location and in a diurnally fluctuating cabinet (60°C/15°C). There was significant variation among genotypes in the pattern of seed softening over the first 5 months after senescence. Cultivars Nungarin, Dwalganup, and Geraldton softened most rapidly in late February, whereas cultivars Dalkeith, Urana, and Izmir softened most rapidly in late March. The duration of field exposure required in order for 50% of the first season’s softening to occur ranged from 44 to 108 days among the 20 genotypes. Persistence of hard seeds into the second and third years also varied among genotypes. Of the cultivars, Nungarin and Izmir had the highest levels of residual hard seed after 30 months (5.3% and 3.9%, respectively), whereas Dalkeith had the lowest (0.9%). Site of seed production had a small but significant effect on both the pattern of softening in the first summer–autumn and the persistence of hard seeds in subsequent years. Seeds produced in a relatively high-rainfall site (768 mm of growing-season rainfall plus supplementary irrigation) had a slower rate of hard seed breakdown than those from either of 2 sites located in the wheatbelt (217 and 423 mm growing-season rainfall). Seed softening through exposure in the field and in a 60°C/15°C fluctuating-temperature cabinet was compared for all genotypes. The cabinet treatment was fairly successful in ranking genotypes for relative between-season hardseededness, although it underestimated total softening by an average of 16%. However, the cabinet treatment was a poor predictor of the within-season pattern of seed softening.

Increased seed production of subterranean clover pastures in response to fertilizers supplying calcium

1974 ◽  
Vol 14 (71) ◽  
pp. 749 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Seed Production ◽  
Calcium Concentration ◽  
Field Experiments ◽  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Unit Weight ◽  
Gypsum Plaster ◽  
Total Seed ◽  
Seed Yields

The effects of four common fertilizers containing calcium on seed production in subterranean clover (Trifolium subterraneum) were measured at six locations over five years in a total of fifteen field experiments. Calcium as a sulphate, carbonate or phosphate salt was applied to subterranean clover pastures either at the start of the growing season (autumn) or at flowering (spring). Gypsum, plaster of Paris, or lime gave large increases in seed yield per unit area and also per unit weight of tops. Spring applications of superphosphate increased seed yields in only two out of four experiments. Gypsum applied in spring at 200-500 kg ha-1 was as effective as 2,000 kg ha-1 of lime applied in autumn. Applications of lime in spring were much less effective. Increased seed yields were due to increases in burr yield, seed number per burr, and mean weight per seed. They were usually accompanied by increases in calcium concentration in the seed. Responses in seed production to calcium applications were obtained in all three sub-species of Trifolium subterraneum. In two experiments, newly sown on a soil type on which subterranean clover regeneration and persistence is commonly very poor, applied calcium doubled or quadrupled seed set. In 13 experiments using soils on which subterranean clover had persisted as the major component of the pasture for several years, calcium in the year of application increased the total seed bank by 6 to 31 per cent, and the current seed set by a greater amount.

Seed production and persistence of Carnamah and other early strains of Trifolium subterraneum in the wheatbelt of Western Australia

1967 ◽  
Vol 7 (24) ◽  
pp. 25 ◽  
Author(s):  
GB Taylor ◽  
RC Rossiter
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Western Australia ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Growing Season ◽  
Early Flowering ◽  
The Other ◽  
Factors Affecting ◽  
Seed Yields

Seed production and persistence of the Carnamah, Northam A, Dwalganup, and Geraldton strains of subterranean clover (Trifolium subterraneum L.) were examined in undefoliated swards in the wheatbelt of Western Australia. The early flowering characteristic of Carnamah was not always associated with higher seed yields. Only when there was a well-defined, early finish to the growing season, or when flowering was very much earlier in Carnamah (viz., following an early 'break' to the season), did this strain clearly outyield both Northam A and Geraldton. The seed yield of Dwalganup was generally inferior to that of the other strains. Factors affecting regeneration are discussed. Under low rainfall conditions, poorer germination-regulation of Carnamah, compared with Geraldton and Northam A, would be expected to result in poorer persistence unless offset by higher seed yields in the Carnamah strain.

The effects of frosts on seed production in subterranean clover (Trifolium subterraneum)

1971 ◽  
Vol 11 (49) ◽  
pp. 202 ◽  
Author(s):  
WR Scott
Keyword(s):  
New Zealand ◽  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
The Past ◽  
Seed Yields

Six cultivars of subterranean clover, Geraldton, Yarloop, Woogenellup, Clare, Mount Barker, and Tallarook, were grown as ungrazed swards at 1,700 feet a.s.1. in the Mackenzie Country of South Canterbury, New Zealand. In this very frosty environment seed yields tended to increase with increasing lateness of flowering although Clare and perhaps Tallarook appeared to be more frost susceptible than the other cultivars. It is suggested that the deleterious effects of frosts in reducing the seed yields of subterranean clover may have been overemphasized in the past and that the trend for seed yields to increase with increasing lateness of flowering can be partially explained by differences in runner production.

Effect of burr burial on seed production of Trifolium subterraneaum subsp. brachycalycinum and other annual legumes

1986 ◽  
Vol 26 (1) ◽  
pp. 59 ◽  
Author(s):  
MDA Bolland ◽  
WJ Collins
Keyword(s):  
Seed Production ◽  
Sandy Soil ◽  
Seed Weight ◽  
Trifolium Subterraneum ◽  
Annual Legumes ◽  
Seed Yields

On sandy soil near Esperance, W.A., prevention of burr burial compared with covering developing burrs with sand drastically reduced the seed production of three subspp. of Trifolium subterraneum (brachycalycinum, subterraneum and yanninicum) and of T. israeliticum by reducing burr production and seed weight. However, T. globosum produced similar amounts of seed from unburied and buried burrs. On sandy soil at Shenton Park, Perth, W.A., prevention of burr burial also reduced seed production of T. subterraneum subspp. brachycalycinum and subterraneum, this being due to fewer burrs, fewer seeds per burr and lighter seed. For subsp. brachycalycinum, seed yields were two to five times greater from burrs which developed within loose gravel than from those developed over sand (in which fewer burrs were able to bury) as a result of increased production of burrs, more seeds per burr and heavier seed. However, for subsp. subterraneum seed yields were similar from burrs whether developed over gravel or sand.

scholarly journals Harvesting subterranean clover seed – current practices, technology and issues

2021 ◽  
Vol 72 (3) ◽  
pp. 223
Author(s):  
Wesley M. Moss ◽  
Andrew L. Guzzomi ◽  
Kevin J. Foster ◽  
Megan H. Ryan ◽  
Phillip G. H. Nichols
Keyword(s):  
Soil Erosion ◽  
Case Studies ◽  
Seed Production ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Root Cause ◽  
Pasture Plant ◽  
Clover Seed ◽  
Production Industry ◽  
Pasture Legume

Subterranean clover (Trifolium subterraneum L.) is Australia’s most widely sown annual pasture legume. Its widespread use as a pasture plant requires a well-functioning seed production industry, and Australia is the only significant producer of subterranean clover seed globally. However, the sustainability of this industry is under threat due to its reliance on ageing harvest equipment and the resultant environmental impacts. In order to evaluate seed harvesting practices, technology, and issues, we report on case studies, workshops, and a survey of seed producers across southern Australia. The Horwood Bagshaw Clover Harvester, designed in the 1950s, remains the most popular subterranean clover seed harvester. We discuss its use and modifications, and document several contemporary issues facing the seed production industry. Issues are primarily soil erosion and degradation; the expensive, slow and labour-intensive harvest process; and poor reliability and maintainability of harvesters that are now at least 30 years old. We conclude the root cause of these issues is the suction harvest technology utilised by the Horwood Bagshaw Clover Harvester. Analysis of the current harvest system is provided to support the development of new approaches to harvest subterranean clover seeds.

The influence of maturity grading on total yield and seed production in strains of Trifolium subterraneun L. grown as single plants and in swards

1959 ◽  
Vol 10 (3) ◽  
pp. 305 ◽  
Author(s):  
RC Rossiter
Keyword(s):  
Soil Moisture ◽  
Seed Production ◽  
Plant Density ◽  
Total Yield ◽  
Subterranean Clover ◽  
Reverse Situation ◽  
Production Pattern ◽  
Seed Yields ◽  
The Relationship ◽  
Early Strain

A large number of strains of subterranean clover was grown as single plants and in swards in a series of 1-year experiments. The relationship between the interval from seeding to flowering ("maturity grading") and the production pattern varied according to plant density. In the case of single plants, both total yields and seed yields increased linearly with increasing maturity grading. With swards, on the other hand, total yields showed scarcely any relation to increasing maturity grading – there was a slight decline, in fact – while seed production fell rapidly. Hence the early strain Dwalganup gave the lowest seed yields as single plants, but the highest seed yields in swards, whereas the reverse situation held for the late strains Wenigup and Tallarook. The main factor responsible for the differences in these production patterns was considered to be available soil moisture supply. It was shown that in the few cases where soil moisture was severely limiting in spring for single plants, yields levelled off (and seed yields even declined) at higher maturity gradings. Three points are discussed at some length: the influence of environment on the seed yield of strains grown as single plants, the effect of plant density on the ratio seed weight/total weight, and production in relation to maturity grading in swards.

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.

Effects of phosphorus on seed yields of subterranean clover, serradella and annual medics

1985 ◽  
Vol 25 (3) ◽  
pp. 595 ◽  
Author(s):  
MDA Bolland
Keyword(s):  
Seed Yield ◽  
Subterranean Clover ◽  
Average Weight ◽  
The Third ◽  
Hard Seeds ◽  
Annual Medics ◽  
Alternating Temperature ◽  
Seed Yields ◽  
The Relationship ◽  
Number Of Seeds

In three experiments located near Esperance, Western Australia, the effect of superphosphate phosphorus on seed yields of subterranean clover, serradella and annual medics was measured on newly-cleared soils, using low seeding rates. In two experiments, the relationship between seed yield and the amount of phosphorus applied was linear for subterranean clover and serradella; seed yields increasing by 7-24 kg/ha for each kg/ha of phosphorus applied, depending on species, strain or cultivar, and location. In the third experiment, seed yields of annual medic species also increased markedly with increasing amounts of applied superphosphate phosphorus, this response also depended on species and strain or cultivar, but the responses become less marked with increasing amounts of phosphorus. For the annual medic species, the phosphorus treatments had no effect on average weight of one burr, number of seeds per burr, weight of one seed, or the rate of softening of hard seeds as measured both in a 15/60� alternating temperature oven (one cycle/day) or for samples of burrs collected periodically during summer from the field. For all legumes, the appearance of first flowers was not affected by phosphorus treatment.

Desiccation of alfalfa for seed production with diquat and glufosinate

1996 ◽  
Vol 76 (3) ◽  
pp. 435-439 ◽  
Author(s):  
J. R. Moyer ◽  
S. N. Acharya ◽  
J. Fraser ◽  
K. W. Richards ◽  
N. Foroud
Keyword(s):  
Key Words ◽  
Seed Production ◽  
Seed Yield ◽  
Seed Weight ◽  
Viable Seed ◽  
Hard Seed ◽  
Alfalfa Seed ◽  
Percent Germination ◽  
Medicago Sativa L ◽  
Seed Yields

Recommendations for desiccation of alfalfa do not clearly define the stage at which desiccants should be applied. To obtain this information, diquat and glufosinate were applied to alfalfa (Medicago sativa L) from 1991 to 1994 at various stages of maturity to determine the effect of desiccant and stage of maturity at desiccation on seed yield 1000-seed weight and seed germinability. Alfalfa seed yields, 1000-seed weights, percent germination and percent viable seed were similar after desiccation with diquat and glufosinate. Desiccation when 60–75% of the alfalfa seed pods were brown permitted maximum seed yields. Percent germination increased slightly in seeds that were exposed to weathering under normal conditions until all pods turned brown. Both desiccants adequately desiccated alfalfa for harvesting but desiccation with glufosinate took 2 or 3 d longer than diquat. Desiccants did not reduce alfalfa growth in the spring after application. Key words: Germination, yield, hard seed, seed weight, stage

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