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.

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.

Effect of time of application of MCPA and bromoxynil in relation to flowering on subterranean clover seed yield and quality

1996 ◽  
Vol 36 (2) ◽  
pp. 177 ◽  
Author(s):  
BS Dear ◽  
GA Sandral ◽  
JE Pratley ◽  
NE Coombes
Keyword(s):  
Seed Yield ◽  
Recovery Period ◽  
Subterranean Clover ◽  
Germination Percentage ◽  
Yield Component ◽  
Yield Response ◽  
Herbicide Application ◽  
Early Application ◽  
Primary Yield ◽  
Herbage Yield

The importance of stage of phenological development and cultivar maturity ranking in influencing the seed yield response of subterranean clover (Trifolium subterraneum L.) to broadleaf herbicides was examined in a field study in southern New South Wales. The herbicides, bromoxynil (200 g a.i./L) at 1.4 L/ha and MCPA (500 g a.i./L) at 1.0 Wha, were applied 6 (TI) and 3 weeks (T2) before flowering, and at 5% flowering (T3) to 7 cultivars ranging from early to late flowering. The stage of phenological development at herbicide application, the maturity ranking of the cultivar and the herbicide applied, all influenced seed set. Application of bromoxynil at T1 did not reduce seed yield of any cultivar but increased seed yield of 4 cultivars by up to 30%. MCPA applied at the same time reduced seed yield in 1 cultivar by 26% and increased yields in 4 others by up to 57%. Application of bromoxynil at T3 caused reductions in seed yield in 3 of the 7 cultivars. MCPA applied at this time was more damaging than bromoxynil with all cultivars showing large seed yield reductions ranging from 22 to 64%. Despite large reductions in herbage yield as a result of some herbicide treatments, there was only a low correlation (r = 0.3, P<0.01) between herbage yield at full flower and seed yield. Our findings suggest that the reduction in herbage yield and change in canopy structure as a result of the early application of herbicides stimulated seed production. Seed number was the primary yield component responsible for the change in seed yield with a high correlation (r = 0.86, P<0.01) between these 2 parameters. Seed size was relatively insensitive to herbicide treatment but varied markedly with cultivar. Germination percentage of seed produced by swards treated with bromoxynil was unaffected, even when applied at T3, whereas MCPA lowered germination percentage of almost all cultivars if applied within 3 weeks of the commencement of flowering. The maturity ranking of the cultivars was highly negatively correlated with percentage seed yield loss (r = -0.80, P<0.01) when either herbicide was applied at T3, the seed yield of the early flowering cultivars being most depressed by the herbicides. Length of recovery period between herbicide application and flowering was shown to be very important in influencing seed yield, the effect being modified by both herbicide and cultivar maturity.

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.

Adaptation of lentil (Lens culinaris Medik) to short season Mediterranean-type environments: response to sowing rates

1998 ◽  
Vol 49 (7) ◽  
pp. 1057 ◽  
Author(s):  
K. H. M. Siddique ◽  
S. P. Loss ◽  
K. L. Regan ◽  
D. L. Pritchard
Keyword(s):  
Seed Yield ◽  
Seed Weight ◽  
Plant Density ◽  
Germination Percentage ◽  
Yield Response ◽  
Individual Plant ◽  
Asymptotic Model ◽  
Growing Conditions ◽  
The Cost ◽  
Seed Yields

The growth and seed yield response of lentil (cv. Digger) to sowing rate (20-120 kg/ha) was studied at 13 sites over 3 seasons in the cropping regions of south-western Australia. The economic optimum plant density was estimated by fitting an asymptotic model to the data and calculating the sowing rate above which the cost for additional seed was equivalent to the revenue that could be achieved from the extra seed yield produced, assuming a 10% opportunity cost. On average across all sites and seasons, only 51% of sown seeds emerged. Increasing sowing rate resulted in greater dry matter production at ˚owering and maturity, and fewer pods per plant. Harvest index (0·31-0·36), number of seeds per pod (1·13-1·84), and mean seed weight (2·9-3·6 g/100 seeds) remained relatively stable with changes in sowing rate. The asymptotic models fitted to seed yields accounted for 1-73% of the total variance in the data, except at one site where a model could not be found to provide an adequate fit to the data. In addition to this site, another 5 sites were excluded from further consideration where the percentage of variance accounted for was <25% or the predicted optimum densities and seed yield potentials were well beyond the range of the data. The economic optimum of the remaining 7 sites ranged from 96 to 228 plants/m2, with a mean of 146 plants/m2. These results suggest that lentil yields may be improved by increasing sowing rates beyond those currently targeted in southern Australia (100-125 plants/m2). On the basis of these results, targeting a density of about 150 plants/m2 by using a sowing rate of approximately 90-110 kg/ha is recommended, depending on mean seed weight and germination percentage of the seed. Even higher sowing rates may be optimum where the growing conditions are unfavourable and individual plant growth is limited.

Influence of cultivar and season on the response of Trifolium subterraneum to simazine

1992 ◽  
Vol 32 (8) ◽  
pp. 1095 ◽  
Author(s):  
BS Dear ◽  
DJ Conlan ◽  
MF Richards ◽  
NE Coombes
Keyword(s):  
Seed Set ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Yield Response ◽  
Yield Losses ◽  
Lolium Rigidum ◽  
Herbage Yield ◽  
Annual Grasses ◽  
Clover Seed ◽  
Seed Yields

The tolerance of 6 cultivars of Trifolium subterraneum (subterranean clover) to simazine applied at 0.63 and 1.25 kg a.i./ha was determined under weedfree conditions in the field by measuring herbage and seed yields. Large herbage yield losses occurred as a result of the simazine in spring in the 2 years of the experiments. In 1989, spring herbage yield losses of the cultivars at the 0.63 and 1.25 kg/ha simazine rates averaged 56 and 82%, respectively. In 1990 the spring herbage yield losses were 27 and 51%. Significant variation in tolerance was observed between cultivars in both years, with Trikkala being the most tolerant and Karridale the most susceptible cultivar. Rate of herbicide had the greatest effect on herbage yield, with cultivar having a smaller effect. In 1989, with relatively favourable spring conditions, clover seed yields were depressed by simazine, but in 1990 when drier conditions prevailed during flowering and seed set, seed yields were unaffected or slightly increased by simazine in all cultivars except the early-flowering cultivar Dalkeith. Seed yields of simazine-treated swards were 196-1480 kg/ha in 1989 and 359-686 kg/ha in 1990. The seed yield response in 1990 suggests that herbicides which retard growth in winter help to conserve soil water and, therefore, may benefit seed filling later in the season. The presence of Lolium rigidum at spraying did not reduce the effect of the herbicide on clover herbage yield and had no effect on seed set. Although simazine may reduce herbage yields and, in some cases, seed yields, its use may be justified for the control of annual grasses when other factors such as disease control, pasture quality, and level of weed competition are considered.

The effect of boron supply on the growth and seed production of subterranean clover (Trifolium subterraneum L.)

1987 ◽  
Vol 38 (3) ◽  
pp. 537 ◽  
Author(s):  
BS Dear ◽  
J Lipsett
Keyword(s):  
Seed Yield ◽  
Seed Set ◽  
Acid Soils ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Seed Formation ◽  
The Past ◽  
Foliar Symptoms ◽  
Buried Seed ◽  
Seed Yields

There has been little research on the boron (B) status of subterranean clover, despite strong indications of deficiency of B in southern Australia where clover decline has been reported. This paper describes glasshouse experiments to vary the level of B supply to clover grown on soils low in B. On a soil farmed in a cereal clover rotation, herbage yields of clover increased by 25% with applied B, but seed yields, negligible without B, increased 21-fold. On two other acid soils, from pastures, there were also large responses to B in seed yield (1.5- and 5.1-fold respectively); liming increased the responses (8- and 55.2-fold). However, herbage production was less responsive to B (25% and 1.7-fold with liming); on the unlimed soils, application of B depressed yield (- 1 and -21%). This is attributed to there being enough B to sustain herbage growth, but inadequate for seed formation. These results show that herbage yield, conventionally employed in the past, is not a satisfactory index of B status for total performance in subterranean clover. The response to B in seed yield was associated with increases in: numbers of seed set (75% to 22.6-fold, depending on the particular combination of soil and liming); size of seed (10% to 1.2-fold); proportion of buried seed (20%-70%). It is suggested that these favour establishment and persistence of clover and that clover decline may well involve deficiency of B. It was shown that concentration of B in the plant does not necessarily relate predictably to yield of herbage and that reduction in seed yield may not be heralded by foliar symptoms, since seed requirement exceeds that of herbage.

The effect of copper supply on vegetative and seed yield of pasture legumes and the field calibration of a tissue test for detecting copper deficiency. I. Subterranean clover (Trifolium subterraneum and Trifolium yanninicum)

1989 ◽  
Vol 40 (4) ◽  
pp. 817 ◽  
Author(s):  
JD McFarlane
Keyword(s):  
Seed Yield ◽  
Dry Matter ◽  
Copper Deficiency ◽  
Critical Concentration ◽  
Leaf Tissue ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Soil Types ◽  
Yield Response ◽  
Pasture Legumes

Three cultivars of subterranean clover (Trifolium subterraneum L. cvv. Woogenellup, Nungarin; Trifolium yanninicum cv. Trikkala) were grown on three copper-deficient soil types at seven rates of copper, applied at sowing, to determine their vegetative and seed yield response to copper fertilizer.On two soil types, symptoms of copper deficiency were apparent where no copper was supplied. On the third, symptoms appeared only in one season, after the site was waterlogged. On the three soil types, the symptoms disappeared when 0.125 kg Cu/ha was applied at sowing. although at this rate vegetative and seed yields were reduced by as much as 44% and 59% respectively.The proposed critical concentration range in youngest open leaf tissue for both diagnosing maximum vegetative dry matter and predicting maximum seed yield is 3.0-4.5 mg Cu/kg for Woogenellup and Nungarin subterranean clover. Trikkala subterranean clover had higher critical concentration ranges for diagnosing maximum vegetative dry matter (4.0-6.0 mg Culkg) and predicting maximum seed yield (4.5-7.0 mg Cu/kg). It was not clear whether this difference was due to a higher internal requirement for copper of Trikkala or overlying environmental conditions affecting the external copper supply at the time of sampling.For whole top tissue (WT), there was no difference in the critical concentration range between the three cultivars for diagnosing maximum vegetative yield (3.0-4.0 mg Cu/kg). However, the critical concentration in WT for predicting maximum seed yield was higher for Trikkala (5.0-6.0 mg Cu/kg) than Woogenellup and Nungarin (3.5-4.5 mg Cu/kg). In the pasture situation, a critical concentration of 5.0-6.0 mg Cu/kg in the WT should be adopted when animal requirement is considered.Seed copper concentration for predicting maximum seed or vegetative yield was not a reliable indicator of copper status of subterranean clover.

The effect of calcium supply on bur set and seed formation in subterranean clover (Trifolium subterraneum L.)

1973 ◽  
Vol 24 (6) ◽  
pp. 839 ◽  
Author(s):  
PG Ozanne ◽  
KMW Howes
Keyword(s):  
Seed Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Calcium Sulphate ◽  
Calcium Deficiency ◽  
Seed Formation ◽  
Buried Seed ◽  
Calcium Supply ◽  
Glasshouse Experiment ◽  
Seed Yields

In a glasshouse experiment subterranean clover plants were grown in soil at various levels of calcium nutrition. The developing burs were buried in separate soil containers to which no nutrients, calcium sulphate, calcium carbonate, or potassium sulphate were applied. When subterranean clover was growing in soil low in calcium, top yield was little affected; but bur and seed formation were greatly reduced. However, when the reflexed flowers were buried in soil to which a calcium salt had been added, bur and seed yield increases of up to 500% were obtained The increase in seed yield resulted from a greater percentage of flowers forming bur, more seed per bur, heavier seed, and less rotten seed. Similar results were obtained in a second glasshouse experiment in which a different soil was used to grow the clover. The beneficial effect of calcium ions around the developing bur was independent of the associated anions, or of the soil pH; nor could it be produced by the substitution of potassium or magnesium for calcium. It seems likely that commercial seed yields and subterranean clover persistence in many areas may be reduced by calcium deficiency in apparently lush healthy pastures. The similarity of this disorder to calcium deficiency in peanuts suggests that other crop and pasture species forming buried seed may also be especially susceptible.

Change in stomatal resistance and water use in subterranean clover (Trifolium subterraneum L.) in response to broadleaf herbicides

1996 ◽  
Vol 47 (4) ◽  
pp. 625 ◽  
Author(s):  
BS Dear ◽  
GA Sandral ◽  
NE Coombes
Keyword(s):  
Water Use ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
Moisture Stress ◽  
Stomatal Resistance ◽  
Herbicide Application ◽  
Herbicide Treatments ◽  
Daily Water ◽  
Saving Effect ◽  
Reduced Water

The effect of 5 broadleaf herbicides on the water use and stomatal resistance of 2 cultivars of subterranean clover (Trifolium subterraneum L.) was examined in a glasshouse study. The herbicide treatments 2,4-DB, MCPA, bromoxynil, MCPA+terbutryn, and MCPA+diuron were applied at 6 rates at 2 times (14 May, 14 June) to plants at 2 leaf stages (3-4 and 8-10 leaves). Each of the herbicides reduced water use by the clover within 24 h, the size of the reduction increasing with the rate of herbicide applied. The herbicide treatments MCPA+terbutryn, MCPA+diuron, and bromoxynil caused the largest reductions (44-52%) in total water use over the 30-day period when applied at the recommended rate, and MCPA and 2,4-DB the least reduction (16-22%). Stomatal resistance increased substantially within 2 days of application of each of the herbicides. The magnitude of the change differed with herbicide and increased with herbicide rate. The effect of the herbicides on stomatal resistance declined 10-20 days after herbicide application in all treatments except 2,4-DB, but stomatal resistance of all herbicide-treated plants was still higher than the control 30 days after herbicide application. The herbicides LICPA+terbutryn and LlCPA+diuron and bromoxynil caused the largest increase in stomatal resistance and 2,4-DB the least. Stomatal resistance was found to be highly negatively correlated with daily water use by the clover plants at 2 days (r = -0.84, P < 0.01) and 30 days (r = -0.88, P < 0.01) after herbicide application. All of the herbicides reduced the LA1 of the plants, the effect increasing as the herbicide rate increased. Herbicide and herbicide rate had the largest effect on both water use and stomatal resistance; the effect of cultivar, leaf stage, and spraying time accounted for a relatively small proportion of the variance. The findings support the hypothesis that some broadleaf herbicides can result in a water-saving effect in subterranean clover swards through increasing stomatal resistance and decreasing the LAI, thereby potentially reducing moisture stress during seed set.

An analysis of seed yield in some strains of subterranean clover (Trifolium subterraneum L.) when grown in binary mixtures

1981 ◽  
Vol 32 (3) ◽  
pp. 445 ◽  
Author(s):  
RC Rossiter ◽  
MJ Palmer
Keyword(s):  
Competitive Advantage ◽  
Seed Yield ◽  
Subterranean Clover ◽  
Trifolium Subterraneum ◽  
The Other ◽  
Pair Member ◽  
Replacement Series ◽  
Beginning Of Flowering ◽  
Seed Yields

Two experiments using various strains of subterranean clover are described. The first experiment was conducted in the field with mixtures of Dwalganup/Northam A, DwalganupI/Daliak and Yarloop/Seaton Park, and the second in an open-sided glasshouse with Yarloop/Seaton Park. In the field experiment, the plots were grazed continuously from late July until early November when the swards were completely dry; in the glasshouse experiment, the swards were defoliated weekly until shortly after the beginning of flowering. Mixtures were arranged according to the de Wit replacement series. Seed yields for the Dwa1ganup/Northam A mixture showed the classical (de Wit) competition for the same resources, with Northam A the better competitor. On the other hand, for the Dwalganup/Daliak and Yarloop/Seaton Park mixtures there was no clear evidence of a competitive advantage of one strain over the other pair member, at least under our defoliated conditions. Whether or not this absence of 'competition' (as usually understood) is common in clover-strain mixtures is as yet unknown. We emphasize, however, that long-term success of clover strains in mixtures is not invariably associated with competitive advantage.

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