The effects of length of growing season, with and without defoliation, on seed yield and hard-seededness in swards of subterranean clover

1981 ◽  
Vol 32 (5) ◽  
pp. 783 ◽  
Author(s):  
WJ Collins
Keyword(s):  
Seed Yield ◽  
Subterranean Clover ◽  
Growing Season ◽  
Absolute Scale ◽  
Growing Seasons ◽  
Short T2 ◽  
Relative Scale ◽  
Seed Yields

The effects of length of growing season and defoliation on seed yield and hard-seededness were examined in two strains of subterranean clover (Seaton Park, Midland B) grown in swards in the field. All plots were sown at the same time and the length of growing season was varied by altering the time of finish of the season (by withholding water). There were three length of growing season treatments: T1 (short), T2 (intermediate) and T3 (control). The defoliation treatments were D0, uncut (control), and D1, defoliated at weekly intervals until the commencement of flowering. Reducing the length of growing season drastically reduced seed yield. Thus when the growing season was only 3 weeks shorter than the control (i.e. T2 compared with T3), seed yields averaged over strains and defoliations were reduced by at least one half. With a further reduction of 2 weeks in the length of the season (T1) seed yields were only about one-third of those obtained in the control (T3). The reductions in seed yield were due to reductions in both the number of mature burrs produced and to a lesser extent in mean weight per seed. Although defoliation increased seed yield in all growing seasons, the effect when measured on a relative scale was greater in T2 than in either T1 or T3. But on an absolute scale the size of the response was greater in T2 and T3 than in T1. The rate of breakdown of hard-seededness was faster in Seaton Park than in Midland B, but it decreased in both strains with increasing length of growing season.

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.

Response of chickpea (Cicer arietinum L.) varieties to time of sowing in Mediterranean-type environments of south-western Australia

2006 ◽  
Vol 46 (3) ◽  
pp. 395 ◽  
Author(s):  
K. L. Regan ◽  
K. H. M. Siddique ◽  
N. J. Brandon ◽  
M. Seymour ◽  
S. P. Loss
Keyword(s):  
Seed Yield ◽  
Western Australia ◽  
Agronomic Traits ◽  
Growing Season ◽  
Northern Region ◽  
Grain Legume ◽  
Sowing Time ◽  
Growing Seasons ◽  
Legume Crop ◽  
Seed Yields

Chickpea has become an important grain legume crop in Australia over the last decade. New varieties with improved seed yield and quality are being developed in Australia with varied phenological and agronomic traits. This study examined the optimum time of sowing of several desi chickpea varieties (Dooen, T1587, Sona and Tyson) varying in phenology over a range of dryland Mediterranean-type environments in south-western Australia. Chickpea showed good adaptation, particularly in the northern grain belt of Western Australia where growing conditions are warmer than southern areas. Seed yields varied widely depending on the time of sowing, location and seasonal conditions. Mean seed yields greater than 1000 kg/ha and up to 2000 kg/ha were achieved, but in some cases seed yields were less than 800 kg/ha. In the northern region, seed yield was almost doubled by sowing in early-May (1625 kg/ha) compared with late-June (754 kg/ha). In contrast to this, seed yields were generally lower in the southern regions and greater from late-June sowings (865 kg/ha) compared to earlier mid-May sowings (610 kg/ha). Seed yields were not clearly increased by altering sowing time to match the phenology of the variety to the growing season rainfall and temperatures, except at the early sowing times (April and early-May) where Tyson out-yielded all other varieties. This is most likely due to the lack of photoperiod-responsive, long-duration varieties to match early sowing and low temperatures limiting vegetative and reproductive growth in all varieties, especially in southern areas. However, it is likely that early flowering varieties will show greater adaptation and yield performance in short growing seasons, while later flowering varieties will be better suited to longer growing seasons. The study found that there were significant differences in the optimum sowing time between northern, central and southern sites, based on differences in mean daily temperatures and length of the growing season. Generally, the greatest seed yields were produced by sowing between mid to late June at southern sites, and early May at central and northern sites.

The influence of shading on seed yield in subterranean clover

1978 ◽  
Vol 29 (6) ◽  
pp. 1167 ◽  
Author(s):  
WJ Collins ◽  
RC Rossiter ◽  
MA Ramas
Keyword(s):  
Solar Radiation ◽  
Seed Yield ◽  
Unit Area ◽  
Subterranean Clover ◽  
Curvilinear Relationship ◽  
Light Supply ◽  
Beginning Of Flowering ◽  
Seed Yields ◽  
Agro Forestry

Swards of three strains of subterranean clover (Woogenellup, Clare and Seaton Park) were subjected to three shading treatments (30%, 55% and 100% of daylight) from the beginning of flowering onwards. For the 100% daylight (unshaded) treatment the incoming daily solar radiation averaged between 20 and 30 MJ/m2. In the unshaded treatment, seed yields for the three strains ranged from about 120 to almost 200 g/m2. These yields were invariably decreased by shading. Moreover the evidence indicated a curvilinear relationship between seed yield and light supply such that at 50% of daylight there was a reduction of rather more than 50% in seed yield. Shading mainly affected the number of inflorescences produced per unit area, although other components of seed yield were also affected adversely. Even late shading (towards the end of flowering) led to lower seed yield, partly associated with lower inflorescence numbers and partly with lower seed numbers per burr. The results are considered to have significance for clover regeneration in mixed clover/grass pastures and also in the cloveritree associations of agro-forestry.

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.

Effect of soil acidity and nutrient deficiencies on the growth and persistence of subterranean clover in pastures grown on sandy soils near Esperance, Western Australia

1985 ◽  
Vol 25 (4) ◽  
pp. 893 ◽  
Author(s):  
MDA Bolland
Keyword(s):  
Seed Yield ◽  
Soil Acidity ◽  
Sandy Soils ◽  
Subterranean Clover ◽  
Nutrient Deficiencies ◽  
The Past ◽  
Ph Values ◽  
Matter Production ◽  
Copper Zinc ◽  
Seed Yields

Most of the sandy soils near Esperance, W.A., were cleared of native vegetation and sown to subterranean clover in the 1950s and 1960s. Over the past 20-30 years, pH values of the topsoil (1:5, soil: water) have decreased from 6.5-7.0 to 5.0-5.5. The application of 2 t/ha of agricultural lime increased the soil pH (1:5, 0.01 CaCl2) from 5.5 to 5.8, from 4.9 to 5.6, and from 5.1 to 5.5 at three sites that had been sown to subterranean clover for 10, 20 and 40 years respectively. However, lime had no effect on either dry matter production or seed yield of subterranean clover. Additions of calcium in a further experiment also did not affect the seed yield of subterranean clover. Irrespective of the lime treatments, the addition of nutrients (phosphorus, potassium, sulfur, copper, zinc, molybdenum, cobalt, manganese and boron) significantly (P<0.05) improved dry herbage yields by a factor of 1.3, 1.7 and 1.4 at the 10-, 20- and 40-year-old sites. However, the addition of nutrients did not affect seed yields of subterranean clover. In other experiments, the omission of sulfur, potassium and, for the deepest sandy site, phosphorus reduced dry herbage yields by between 10-30%. The omission of molybdenum from treatments of the 20- and 40-year-old pasture reduced herbage yields by 21 and 16% respectively. However, omission of molybdenum in the experiment sited on the 10-year-old pasture did not affect yields. Thus, as the acidification of the sandplain soils continues, molybdenum may become deficient and may limit herbage yields of subterranean clover.

Effect of timing of forage conservation on forage yield and quality, seed yield and seedling regeneration of four subterranean clover (Trifolium subterraneum) cultivars

2008 ◽  
Vol 48 (8) ◽  
pp. 1133 ◽  
Author(s):  
B. S. Dear ◽  
B. F. Hackney ◽  
G. M. Dyce ◽  
C. A. Rodham
Keyword(s):  
Seed Yield ◽  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Forage Yield ◽  
Seedling Regeneration ◽  
Yield And Quality ◽  
Cutting Height ◽  
Seed Yields ◽  
Forage Yields

Swards of four cultivars of subterranean clover (Trifolium subterraneum L.) were cut at three different times to determine the effect on forage yield and quality, seed set and seedling regeneration in two successive seasons in southern New South Wales. The four cultivars of subterranean clover (Seaton Park LF, Junee, Goulburn and Clare) were cut on 23–25 September (early cut), 8–10 October (mid cut) or 22–23 October (late cut), to simulate an early silage, late silage or hay cut. Additional treatments imposed included either grazing or leaving the regrowth after cutting and raising the cutting height from 3 to 6 cm. Forage yields ranged from 3.5 to 9.3 t dry matter (DM)/ha in the first year and from 2.0 to 5.9 t DM/ha in the second year. Herbage yield was influenced by both cultivar and harvest time with the highest yields achieved with the mid cut. Lower forage yields at the later cut were attributed to losses due to respiration and decay under dense leaf canopies. Changes in forage quality were consistent across both years, with in vivo DM digestibility declining from 76–79% to 69–70% as cutting time was delayed. Crude protein fell from 22–24% to 14–17% over the same period, depending on cultivar. Seed yields in both years were influenced by both cutting time and cultivar with a positive relationship (R2 = 0.45–0.61) between herbage present in late spring after a period of regrowth and subsequent seed yield. The early flowering cultivar Seaton Park LF had the highest seed yield in both years and the more erect cultivar Clare had the lowest. Seed yields declined with later cutting time but increased by an average of 39% when the cutting height was raised from 3 to 6 cm. Seedling regeneration reflected seed yield responses with the largest seedling regeneration occurring in treatments cut early. The study found that forage conservation in early October is likely to yield more and be of higher quality than swards cut later in the season. Seed set is greatly reduced by all cutting strategies to levels unprofitable for seed harvesting but may be adequate for pasture regeneration.

Chemical Control of Dandelion (Taraxacum officinale) and Perennial Sowthistle (Sonchus arvensis) in Alfalfa (Medicago sativa) Grown for Seed

Weed Science ◽  
1980 ◽  
Vol 28 (2) ◽  
pp. 164-167 ◽  
Author(s):  
J. Waddington
Keyword(s):  
Medicago Sativa ◽  
Seed Yield ◽  
Chemical Control ◽  
Growing Season ◽  
Taraxacum Officinale ◽  
Alfalfa Seed ◽  
Visible Effect ◽  
Sonchus Arvensis ◽  
Dichlorophenoxy Acetic Acid ◽  
Seed Yields

Applications of 2,4-D [(2,4-dichlorophenoxy)acetic acid] at 1.1 kg/ha at the start of each growing season severely damaged established alfalfa (Medicago sativaL. ‘Beaver’) and reduced seed yield 32% over a 4-yr period. Dandelion (Taraxacum officinaleWeber) populations were reduced but perennial sowthistle (Sonchus arvensisL.) increased in frequency. Dichlobenil (2,6-dichlorobenzonitrile) applied at 2.1 kg/ha controlled both dandelion and perennial sowthistle. Alfalfa was damaged initially but rapid recovery resulted in an increase in seed yield in 2 yr out of 4. Terbacil (3-tert-butyl-5-chloro-6-methyluracil) applied at 1.1 kg/ha also controlled dandelion and perennial sowthistle. No alfalfa damage was evident and seed yields were increased 34% over a 3-yr period. Seed yield increased 30% where asulam (methyl sulfanilylcarbamate) was applied at 4.5 kg/ha, but there was no visible effect on the growth of either alfalfa or weeds. Simazine [2-chloro-4,6-bis (ethylamino)-s-triazine], propham (isopropyl carbanilate) + PCMC (p-chlorophenyl-N-methyl carbamate), pronamide [3,5-dichloro(N-1,1-dimethyl-2-propynyl)benzamide], and diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea], did not affect alfalfa seed production significantly, although simazine and diuron did reduce dandelion populations.

Infection of subterranean clover swards with bean yellow mosaic potyvirus: losses in herbage and seed yields and patterns of virus spread

1994 ◽  
Vol 45 (7) ◽  
pp. 1427 ◽  
Author(s):  
RAC Jones
Keyword(s):  
Field Experiments ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Yield Losses ◽  
Grazing Experiment ◽  
Growing Seasons ◽  
Heavy Grazing ◽  
Herbage Yield ◽  
Seed Yields ◽  
Grazed Swards

During 1989-92, subterranean clover ( Trifolium subterraneum L.) was grown in field experiments in which swards of six cultivars were infected with bean yellow mosaic potyvirus (BYMV) by transplanting small BYMV-infected subterranean clover plants into them. The swards were then grazed by sheep or mown to simulate grazing. The infected transplants were the primary virus source for subsequent spread by aphids. Spread initially centred on infected transplants resulting in circular expanding infected patches. Later, secondary patches, isolated affected plants and more generalized infection sometimes developed. The extent of spread within swards from the transplants varied with cultivar, BYMV isolate, site and year. Final BYMV incidence ranged from 12% of plants symptom-affected by isolate MI in cv. Junee in 1991 to 100% by isolate SMB in cv. Leura in 1992. BYMV spread mostly occurred in spring and was increased around the edges of areas of bare ground in swards. In two experiments at one site in which 'mini swards' of cvv. Green Range, Karridale and Leura were mown repeatedly, BYMV-infection decreased herbage yields (dry weights) by 12-16% while seed yields were decreased significantly (by 37-40010) in one experiment. In a grazing experiment at a second site with swards of cvv. Esperance and Karridale, BYMV-infection decreased overall yields of herbage by 18-39% and seed by 11-12%; herbage yield losses within symptom-affected patches were 28-49%. In a further grazing experiment at this site with swards of cvv. Junee and Karridale, BYMV-induced losses determined from symptom-affected patches were 21-29% for herbage and 15-25% for seed. In a grazing experiment with swards of cvv. Denmark and ~ e u r a ' at a third site, BYMV-induced overall herbage yield decreases of 8-12% were still recorded despite extensive BYMV spread to control swards; yield losses within symptom-affected patches were 18-25% for herbage and 35-47% for seed. Seed yield losses were due to decreased seed size (mean seed weight), fewer seeds being produced, or both. Estimates of the effects of different levels of BYMV infection on herbage yields in partially infected grazed swards were obtained for cvv. Denmark, Karridale and Leura by plotting individual quadrat data for herbage dry weights against % symptom-affected plants. Losses increased in proportion to the level of infection, but their magnitude also varied with cultivar and experiment. It is concluded that BYMV infection of subterranean clover pastures is cause for concern, not only as regards herbage yield losses but also as regards depletion of the seed bank, which, when compounded year by year, results in pasture deterioration. Early and prolonged aphid activity, reseeding the pasture with susceptible cultivars, heavy grazing and extended growing seasons are all likely to magnify BYMV-induced losses.

Evolution of subterranean clover in South Australia. II. Change in genetic composition of a mixed population after 19 years' grazing on a commercial farm

1982 ◽  
Vol 33 (4) ◽  
pp. 679 ◽  
Author(s):  
PS Cocks ◽  
AD Craig ◽  
RV Kenyon
Keyword(s):  
Seed Yield ◽  
South Australia ◽  
Principal Component ◽  
Subterranean Clover ◽  
Mixed Population ◽  
Genetic Composition ◽  
Early Maturity ◽  
Factors Affecting ◽  
High Yields ◽  
Seed Yields

Change in genetic composition of a mixed population of subterranean clover was studied at Kalangadoo in the south-east of South Australia. The seeds from an experiment in which 25 late-maturing strains were compared, were sampled in January 1977, 19 years after the plants were originally sown in 1958. Quadrats along three transects over the approximate position of the old plots were sampled and seed yields measured. The soil was analysed for several chemical and physical properties at the site of each quadrat. Thirty seeds from each sample were germinated in a glasshouse and the resulting seedlings planted out as spaced plants. These were identified on the basis of flowering time and morphological variables; in this way the seed pool of each strain at each quadrat site was determined. Seed pools were adjusted for variation in distance of original plots from the transects by estimating the real position of each plot relative to the transect and calculating the relationship between seed yield and estimated distance. Highest adjusted seed pools were produced by CPI 14454B (820 kg ha-1), CPI 12695 (626 kg ha-1), Eden Valley (502 kg ha-1), and CPI 14197A (476 kg ha-1). Cultivars Mt Barker and Tallarook were also common, but it was deduced from their distribution that they had been continuously introduced to the site from surrounding fields by livestock. All but six of the original strains were recovered in the sampling. Also present were many divergent strains, which yielded 228 kg ha-1 or 31 % of the average seed yield of 744 kg ha-1. Twenty-four of the original 25 strains and five others-Woogenellup, Yarloop, Trikkala, Clare and a divergent strain naturalized at Kalangadoo-were sown in small plots. Twenty-five agronomic variables were measured, including seasonal herbage yields, petiole lengths, leaf areas, isoflavone contents, phosphorus and sulfur uptakes, above- and below-ground seed yields, seed and seedling sizes and permeability of seed coats. The fourth component of a principal component analysis of the data was related to seed pool (P < 0.001), and it is suggested that the variables contributing to this component are important in predicting the success of a strain at Kalangadoo. The most successful tended to have high yields of buried seed, high yields of herbage and long petioles in winter, high formononetin content, early maturity and small seedlings. The results are discussed in terms of factors affecting success, generation of new genetic diversity, and field implications.

Differential tolerance of Trifolium subterraneum L. (subterranean clover) cultivars to broadleaf herbicides. 2. Seed yield and quality

1995 ◽  
Vol 35 (4) ◽  
pp. 475 ◽  
Author(s):  
GA Sandral ◽  
BS Dear ◽  
NE Coombes
Keyword(s):  
Seed Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Germination Percentage ◽  
Yield Response ◽  
Wagga Wagga ◽  
Herbicide Treatment ◽  
Herbicide Treatments ◽  
Saving Effect ◽  
Seed Yields

The effect of broadleaf herbicides on seed set by Trifolium subterraneum (subterranean clover) cultivars was examined at 2 sites (Wagga Wagga and Canowindra) over 2 years. Five commonly used herbicide treatments (bromoxynil, MCPA, 2,4-DB, MCPA + terbutryn, MCPA + diuron) were applied at 2 rates to 7 cultivars of subterranean clover. Significant site x cultivar x herbicide interactions were observed. Seed yields were either unaffected or depressed by up to 66% at the higher rainfall site (Canowindra), whereas at the lower rainfall site (Wagga Wagga) some herbicide x cultivar combinations showed increases in seed yield up to 115%. The increase in seed yield was greater at the lower herbicide rate. The variation in seed yield with herbicide treatment was largely a result of a change (P<0.001) in the number of seeds set (R = 0.94 at Wagga Wagga; R = 0.85 at Canowindra). Seed size was also correlated (P<0.001) with seed yield at both sites but explained less of the variation (R = 0.23 at Wagga Wagga; R = 0.47 at Canowindra). The reduction in herbage yield as a result of herbicide application was a poor indicator of the subsequent seed yield response at both sites. Cultivar Trikkala was consistently most tolerant to the herbicide treatments, showing either no change in seed yield at the wetter site or large increases in seed yield at the lower rainfall site. In contrast, the seed yield of Dalkeith was depressed by 2,4-DB at both sites in both years by 39-66%. Increases in seed yield, which were most pronounced in cultivars of midseason maturity (Trikkala, Junee, Seaton Park) and least in later maturing cultivars (Karridale, Clare) and in the very early flowering Dalkeith, were attributed in part to a water-saving effect of the herbicide treatments. Cultivar maturity ranking was negatively correlated (P<0.001) with seed yield (R=-0.73 at Wagga Wagga; R=-0.45 at Canowindra). The germination percentage of seed produced by the cultivars was unaffected by herbicide treatment, although the number of abnormal radicles formed by germinating seed was higher in the 2,4-DB and MCPA treatments.

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