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

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.

2002 ◽  
Vol 42 (7) ◽  
pp. 1023 ◽  
Author(s):  
J. F. Ayres ◽  
L. A. Lane ◽  
J. R. Caradus ◽  
P. T. P. Clifford

Grasslands NuSiral is a medium–large-leaf white clover (Trifolium repens L.) cultivar with intermediate growth habit (midway between open and erect and dense and prostrate), early flowering maturity and high growing point density. G. NuSiral possesses the plant-type attributes known to be desirable for broad adaptation to dryland pasture conditions in Australia and has been developed for cattle and sheep pastures in both summer rainfall and winter rainfall areas where average annual rainfall exceeds 750 mm. G. NuSiral is expected to provide enhanced stolon survival and autumn recovery in environments where summer moisture stress is present but not intense, and winter growth comparable to cv. Haifa where mild winter conditions allow the expression of G. NuSiral's winter activity.


1996 ◽  
Vol 6 ◽  
pp. 141-143
Author(s):  
D.R. Woodfield ◽  
J.R. Caradus ◽  
G.R. Cousins ◽  
T. Dunn

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,


Author(s):  
B.M. Cooper ◽  
P.T.P. Clifford ◽  
W.M. Williams

Grasslands Challenge (Trifolium repens L.) white clover was developed to incorporate potential growth benefits, and disease resistance, in two double cross hybrids (Mediterranean × New Zealand) identified in evaluations at Kaikohe. Thirty-three elite selections of hybrids and New Zealand material were polycrossed for seed production. Progeny testing resulted in 27 parental lines with improved resistance to leaf disease and stem nematode (Ditylenchus dipsaci) relative to Grasslands Pitau. Testing of the maternal lines for seedling characteristics resulted in the deletion of one parent. A bulk line was evaluated in mini plots, and a hill country grazing trial, and showed improved growth to the control. In a grazing trial conducted in the Manawatu, Challenge showed outstanding winter production. The selection has a high stolon density in combination with a medium to large leaf size. This will allow Challenge to recover quicker from drought stress and grazing pressure. The plant type and early results indicate Challenge will be best suited to a rotational grazing management, particularly in regions where significant cool-season growth occurs. Plant Variety Rights were granted in 1997, and commercial seed should be available in 1998. Keywords: Grasslands Challenge, leaf disease, Mediterranean hybrids, stem nematode, Trifolium repens


Author(s):  
D.R. Woodfield ◽  
I.J. Baird ◽  
P.T.P. Clifford

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


1988 ◽  
Vol 110 (1) ◽  
pp. 145-154 ◽  
Author(s):  
R. Cook ◽  
D. R. Evans

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.


1979 ◽  
Vol 59 (3) ◽  
pp. 713-715 ◽  
Author(s):  
D. M. HUXLEY ◽  
V. C. BRINK ◽  
G. W. EATON

Components of seed yield were studied in white clover (Trifolium repens L.). Head number and seed size were the major components of yield. Seeds per head was not a significant yield component and was independent of head number.


1997 ◽  
Vol 37 (2) ◽  
pp. 159 ◽  
Author(s):  
S. G. Clark ◽  
M. J. McFadden

Summary. The herbage yield, stolon characteristics and soil seed reserves of a diverse range of white clover (Trifolium repens L.) cultivars were studied at Hamilton in south-western Victoria. The cultivars were sown with perennial grass (Phalaris aquatica L.) and the pasture was rotationally grazed by sheep. The aim of the study was to identify white clover types which would persist under sheep grazing. The widely used cultivar, Haifa, fails to persist in this environment. Cultivars were divided into 3 groups depending on leaf size (range 2.5–13.0 cm2). Large-leaved cultivars were the most productive in the first year of the experiment but by year 3 some of the intermediate leaf-size cultivars were the most productive. Haifa (large leaved) was particularly unproductive in the third year compared with other large and intermediate leaf-size cultivars. Stolon characteristics were measured in early spring 1987, mid summer 1988 and early autumn 1988. Total stolon yield on each occasion was 0.46–0.99, 0.65–1.68 and 0.05–0.25 t DM/ha respectively. Intermediate leaf- size cultivars tended to have the highest stolon yields on each occasion. Stolon yield declined at the same rate (mean 87%; range 81–92%) in all cultivars between the second and third sampling date indicating that there is no variation in the cultivars’ ability to survive the summer drought period. Although seed reserves for most cultivars were high at the end of the experiment (range 11–130 kg/ha) no seedling recruitment was observed and seed is thought to play no role in sward survival in this environment. Plant breeders developing white clover cultivars for this environment should concentrate on maximising stolon yield at the beginning and end of the summer drought period (January–mid March). Intermediate leaf-size genotypes are likely to provide the best combination of stolon and herbage yield. Grazing management should also aim to maximise stolon yield at these critical times. The use of large-leaved, non-stoloniferous cultivars should be discouraged by advisers as they are not suited to this marginal environment under sheep grazing.


1985 ◽  
Vol 2 ◽  
pp. 25-31
Author(s):  
P.T.P. Clifford

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.


1989 ◽  
Vol 67 (8) ◽  
pp. 2297-2301 ◽  
Author(s):  
Joanna Fraser

Some characteristics of seven populations of naturalized white clover (Trifolium repens L.) from native pastures in Nova Scotia, Prince Edward Island, and New Brunswick were investigated. Nine vegetative characters were measured on 16- to 18-week-old plants, and within and between population differences determined for cyanogenesis. Variation was observed between and within populations for all measured characteristics. Leaf marks were predominately the central V-shaped chevron; one population had plants without the chevron. Relative leaf size (length × width) ranged from 145 to 784 mm2. Hydrogen cyanide concentrations in leaf laminae were lower in cyanogenic (AcLi) and glucosidic (Acli) genotypes than enzymatic (acLi) genotypes. HCN concentrations in genotypes varied between and within populations. A population from Charlottetown, Prince Edward Island, had several desirable agronomic features, e.g., larger leaves, longer petioles, and thicker stolons than other populations, and could be used in a breeding programme for improved winter-hardy white clover varieties suited for rotational grazing and silage in Atlantic Canada.


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