scholarly journals Response to selection for seed yield in six white clover cultivars

2004 ◽  
pp. 103-110 ◽  
Author(s):  
K.H. Widdup ◽  
D.R. Woodfield ◽  
I.J. Baird ◽  
P.T.P. Clifford
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
White Clover ◽  
Trifolium Repens ◽  
Leaf Size ◽  
Fourth Generation ◽  
Selection Strategy ◽  
Flowering Pattern ◽  
Selection For ◽  
The Impact

The successful commercialisation of agronomically superior white clover (Trifolium repens) cultivars is dependent on their seed production potential. Field trials were established in 2000 and repeated in 2003 to determine the impact of selection for increased seed yield. The seed yield of the pre-release cultivar (the base population prior to selection for seed yield and cultivar release, representing generation 0) was compared with the field Nucleus generation of the released cultivar (second generation after selection for seed yield, representing generation 2) and the Basic seed generation (the fourth generation after selection for seed yield, representing generation 4), in six recent cultivars (Grasslands Kopu II, Grasslands Challenge, NuSiral, Grasslands Sustain, Grasslands Demand and Grasslands Prestige). The Nucleus and Basic generations had consistently higher seed yield than the pre-release generation for all cultivars. These increases in seed yield were associated with increases in inflorescence density (inflorescences/m2) and to a lesser extent with increased seed yield/inflorescence. Changes were also evident in flowering pattern with four of the six cultivars having a sharper flowering peak following selection. This improved uniformity was also evident through reduced variability in leaf size of the Nucleus generation compared to the pre-release generation. Grasslands Kopu II had the highest seed yields which were associated with moderately high inflorescence density in combination with high seed yield/ inflorescence. The selection strategy used in the final phase of the development of these cultivars has proven successful in increasing seed yield through refining flowering pattern and production while maintaining the morphology and uniformity of the new cultivar. Keywords: cultivars, genetic improvement, seed production, Trifolium repens, white clover

Observations on resistance in white clover (Trifolium repens L.) to the stem nematode (Ditylenchus dipsaci (Kühn) Filipjev)

1988 ◽  
Vol 110 (1) ◽  
pp. 145-154 ◽  
Author(s):  
R. Cook ◽  
D. R. Evans
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Significant Positive Correlation ◽  
Leaf Size ◽  
Nematode Reproduction ◽  
Long Period ◽  
Plant Collections ◽  
Ditylenchus Dipsaci ◽  
Trifolium Repens L ◽  
Selection For

SummaryThe expression of symptoms of stem nematode reproduction on a total of 53 white clovers (26 cultivars, 14 genepools and 13 introductions from plant collections) was studied in a series of field and glasshouse experiments. Seedlings or stolon-tip cuttings were inoculated with nematodes and the clovers classified by the proportion of plants which developed symptoms. Significant differences were found between varieties although in each test the majority was intermediate between more resistant and susceptible extremes. There was significant positive correlation between tests, in spite of different inoculation methods and different average levels of susceptibility. Very large-leaved cv. Aran was more resistant than most other clovers tested, and small-leaved cv. S. 184 was more susceptible. There was no general correlation of leaf size with reaction to stemnematode. Small-leaved cv. Pronitro was also resistant while several large-leaved cultivars were susceptible. In observations of plants exposed to nematodes over a long period, either by sequential inoculations or through perpetuating latent infections, apparently resistant plants eventually succumbed and supported nematode reproduction. It has not been determined whether this was because selection for virulence in the nematodes had occurred.

Heritability of frost tolerance in white clover (Trifolium repens)

1990 ◽  
Vol 114 (2) ◽  
pp. 151-155 ◽  
Author(s):  
J. R. Caradus ◽  
A. C. Mackay ◽  
J. Van Den Bosch ◽  
S. Wewala ◽  
D. H. Greer
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Size Effects ◽  
Leaf Size ◽  
Frost Damage ◽  
Frost Tolerance ◽  
Method Of Calculation ◽  
Selection For ◽  
Heritability Estimates ◽  
High Selection

SUMMARYWhite clover genotypes selected for frost tolerance and susceptibility were pair-crossed in various combinations with unselected genotypes of Grasslands Huia. Progeny lines and parent genotypes were artificially frosted at −8°C and scored for percentage of leaves damaged. Progeny from crosses between frost-tolerant genotypes were less damaged by frost than progeny from crosses involving either susceptible genotypes or unselected Grasslands Huia genotypes. Heritability estimates for frost tolerance or susceptibility were high, ranging from 0·75 to 0·93, depending on method of calculation. Removal of leaf-size effects from scores of frost damage reduced heritability estimates to 0·54–0·73. It was concluded that, because heritability for frost tolerance was high, selection for this character and incorporation of frost tolerance into agronomically suitable but frost-sensitive cultivars by breeding would be successful.

EFFECT OF LEAF AREA ON WHITE CLOVER SEED PRODUCTION

1985 ◽  
Vol 2 ◽  
pp. 25-31
Author(s):  
P.T.P. Clifford
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
White Clover ◽  
Management Practices ◽  
Leaf Size ◽  
Fold Increase ◽  
Yield Potential ◽  
Management Options ◽  
Moisture Management ◽  
Clover Seed

Leaf size is a major determinant of white clover seed yield. A three-fold increase in leaf size halves seed yield. From a survey of commercial crops, an optimum leaf size concept was used to explain the reduction in yield potential for extremes in leaf size. Overgrazing gave small leaves and lowered seed yields. Closing too early gave large leaves and lowered yields. With good management, optimum leaf size was the smallest size possible, consistent with ensuring an adequate bulk for efficient harvesting. A healthy highly-reproductive stolen population has to be developed before closing. Secondly, moisture regulation over the crop season, preventing excess watering to minimise plant exploitation of surplus fertility, reduces the potential for large leaves to develop. Mid-November closing coupled with maintaining soil moisture at about 25% plant available, over flowering, are sound management practices. Amongst cultivars, differences in seed yield potential may also be related to leaf size. In general the larger the mean cultivar leaf size the lower the seed yield. Keywords: Trifolium repens, white clover, seed production, leaf size, soil fertiity, moisture, management options.

scholarly journals Response to selection for increased taproot diameter

1996 ◽  
Vol 6 ◽  
pp. 141-143
Author(s):  
D.R. Woodfield ◽  
J.R. Caradus ◽  
G.R. Cousins ◽  
T. Dunn
Keyword(s):  
White Clover ◽  
Trifolium Repens ◽  
Growth Habit ◽  
Leaf Size ◽  
Moisture Stress ◽  
Response To Selection ◽  
Short Term ◽  
Grazing Systems ◽  
Trifolium Repens L ◽  
Selection For

Increased taproot diameter is an important component in maintaining white clover (Trifolium repens L.) growth, nitrogen fixation and persistence during short-term moisture stress. Previous reports indicated selection for large taproot diameter would result in commensurate increases in leaf size and poorer growth habit. The current research investigates the response to selection for taproot diameter and the association between taproot diameter and leaf size in large-leaved clovers suited to dairy grazing systems. Taproot diameter increased by 2.4% per cycle while leaf size and growth habit were not significantly altered. Furthermore, while taproot diameter did not increase between cycle 2 and 3, the root index which measures the ratio of taproot diameter to leaf size increased linearly across all three cycles. These results suggest it is possible to select white clovers for dairying which have larger taproot diameter while maintaining a suitable growth habit. Keywords: dairying, drought, genetic improvement, root morphology, Trifolium repens L., white clover,

Grasslands Trophy — a new white clover (Trifolium repens L.) cultivar with tolerance of summer moisture stress

2007 ◽  
Vol 47 (1) ◽  
pp. 110 ◽  
Author(s):  
J. F. Ayres ◽  
J. R. Caradus ◽  
R. D. Murison ◽  
L. A. Lane ◽  
D. R. Woodfield
Keyword(s):  
Seed Yield ◽  
White Clover ◽  
Trifolium Repens ◽  
Leaf Size ◽  
Moisture Stress ◽  
Yield Potential ◽  
Annual Rainfall ◽  
Progeny Testing ◽  
Eastern Australia ◽  
Trifolium Repens L

A breeding project has developed a new synthetic white clover (Trifolium repens L.) cultivar, Grasslands Trophy, that possesses tolerance of summer moisture stress in dryland pasture environments in the 850–1250 mm average annual rainfall temperate perennial pasture zone in eastern Australia. The breeding strategy used to develop Grasslands Trophy was an in situ breeding cycle for: (i) identifying and selecting superior genotypes, (ii) crossing elite germplasm and (iii) progeny testing derived breeding lines for the expression of key agronomic and grazing value traits. The primary selection criteria were early vigour, herbage yield, persistence and seed yield potential. Parental selection was also applied for seed yield, uniformity of leaf size, uniform flowering pattern and freedom from disease and virus symptoms. Grasslands Trophy is medium–large in leaf size with stable leaf size, combines intermediate stolon density with intermediate stolon thickness, and expresses high stolon survival and strong autumn regrowth following summer moisture stress. Grasslands Trophy has mid-season flowering maturity, intensive flowering prolificacy and high seed yield capability. Agronomic results from trials in northern New South Wales and New Zealand indicate that Grasslands Trophy has broad adaptation, expresses high summer and winter growth activity, and is reliably persistent for at least 4 years.

scholarly journals Genetic control of white clover seed yield potential

2004 ◽  
pp. 111-117 ◽  
Author(s):  
D.R. Woodfield ◽  
I.J. Baird ◽  
P.T.P. Clifford
Keyword(s):  
Genetic Control ◽  
Seed Yield ◽  
White Clover ◽  
Trifolium Repens ◽  
Yield Potential ◽  
Commercial Viability ◽  
Keywords Genetics ◽  
Trifolium Repens L ◽  
Selection For ◽  
Clover Seed

Improving the seed yield potential of new white clover (Trifolium repens L.) cultivars is critical to their commercial viability and to overcoming the increasing pressures from land use change in Canterbury. The genetic control and response to selection was investigated for two seed yield characteristics, inflorescence density (no./m2) and seed yield per inflorescence (g/ inflorescence). Inflorescence density and seed yield per inflorescence were both responsive to selection and acted independent of one another to increase seed yield. Selection for high inflorescence density resulted in 34% higher seed yield than the low inflorescence density selection. This change in seed yield was associated with a 33% higher inflorescence density, while seed yield per inflorescence was unchanged. Similarly, selection for seed yield per inflorescence resulted in a 17% difference in seed yield between the high (HYI) and low (LYI) seed yield per inflorescence selections. This change in seed yield was associated with a 24% higher yield per inflorescence for the HYI selection, while inflorescence density remained unchanged. These results confirm that both mechanisms are under independent genetic control and can be utilized to increase seed yield of new white clover cultivars. Keywords: genetics, inflorescence density, seed production, Trifolium repens, white clover

scholarly journals The practicalities of managing cultivar change

1996 ◽  
Vol 6 ◽  
pp. 25-27
Author(s):  
Dave Allen
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
White Clover ◽  
Trifolium Repens ◽  
Crop Management ◽  
Management Systems ◽  
Trial And Error ◽  
Base Management ◽  
Trifolium Repens L

Ten years experience from trial-and-error plus some advice, has led to the development of successful base management systems for white clover cultivar-change. These systems are capable of modification according to site and season to maximise seed returns and have reached the point where white clover is now my safest crop. This paper considers crop management requirements necessary from the 'change' decision, some years before inception, through to harvested seed yield. Keywords: crop management, cultivar-change requirements, harvest, seed production, sowing technology, Trifolium repens L., white clover

Residue management increases seed yield of three turfgrass species on the Canadian prairies

2002 ◽  
Vol 82 (4) ◽  
pp. 687-692 ◽  
Author(s):  
B. D. Gossen ◽  
J. J. Soroka ◽  
H. G. Najda
Keyword(s):  
Seed Production ◽  
Seed Yield ◽  
Poa Pratensis ◽  
Creeping Bentgrass ◽  
Kentucky Bluegrass ◽  
Residue Management ◽  
Row Spacing ◽  
Seeding Rate ◽  
Canadian Prairies ◽  
The Impact

Little information is available on the management of turfgrass species for seed production in the Canadian prairies. The objective of these studies was to assess the impact of residue management and row spacing on seed yield under irrigation. A factorial experiment was seeded at Saskatoon, SK, in 1993 to assess the impact of burning or scalping (very close mowing with residue removal) vs. mowing, and 20- vs. 40-cm row spacing on seed yield of Kentucky bluegrass (KBG) (Poa pratensis), creeping red fescue (CRF) (Festuca rubra subsp. rubra) and creeping bentgrass (CBG) (Agrostis palustris). Also, a residue management trial on KBG was seeded at Brooks, AB, in 1993. At Saskatoon, yield was higher at 20-cm spacing across all three species in 1994, but spacing had no impact on winter survival, stand density, tiller growth or yield in subsequent years. Burning and scalping consistently resulted in earlier spring green-up, a higher proportion of fertile tillers, and higher seed yield than mowing. Even with residue management, yield declined after one harvest in CBG and CRF, and after two harvests in KBG. At Brooks, residue management had a similar impact on yield of KBG. A second trial at Brooks examined the impact of row spacing (20, 40, 60 cm) and seeding rate (0.5 to 6 kg seed ha-1) on KBG. Seed yield was highest at 40-cm spacings in 1994, at 60 cm in 1995, and at 40 to 60 cm in 1996. Seeding rate did not have a consistent effect on yield. We conclude that a combination of residue management and 20- to 40-cm spacings provide the highest, most consistent seed yields for these turfgrass species in this region. Key words: Burning, clipping, turfgrass, seed production, row spacing, Poa, Festuca, Agrostis

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