White Clover Varieties Research Articles

Evaluation of the effects of resistance to stem nematode (Ditylenchus dipsaci) in white clover (Trifolium repens L.) under sheep grazing and cutting

AbstractTwo field experiments were carried out to analyze the performance of white clover varieties differing in their resistance to stem nematode. Varieties were compared under grazing and cutting regimes in mixed swards with or without the addition of nematode and dry matter yields of white clover and perennial ryegrass recorded over a 3‐year period. The resistant variety did not show a yield advantage in the absence of nematode but did so in the presence of nematode in the first year and for several of the sampling dates in the second year. White clover yields under grazing were significantly less than under cutting in both experiments. The hypothesis that the additional stress of grazing would increase the benefits of resistance relative to a cutting management was not supported.

New generation white clovers for United Kingdom farming systems

White clover is used worldwide to improve the nutritive value of pastures and is an increasingly important component of environmentally-sustainable grassland ecosystems. In 1991, a white clover breeding program involving two New Zealand companies (AgResearch and Midlands Seed) and a European company (Barenbrug), was initiated to develop new varieties for agricultural systems in the United Kingdom. This collaborative international program has been very successful with three improved varieties, Crusader, Barblanca and Makuri, being released and listed in the United Kingdom. The improved persistence and productivity of these varieties has enabled them to secure a significant share of the UK proprietary seed market. In particular, the medium-leaved Crusader produces at least 30% more DM than any other small or medium-leaved white clovers in UK Recommended List trials. Changes in agricultural subsidies within the EU Common Agricultural Policy and the growing pressure to use environmentally sustainable agricultural practices should increase demand for new generation white clover varieties that can maximise both pasture production and animal productivity.

Assessment of Cattle Preference for Perennial Ryegrass Varieties in Association with White Clover. Does White Clover Content Interfere?

AbstractThere is a need to evaluate grass varieties under grazing management to allow selection of varieties to increase animal performance. However, the evaluation of animal performance under grazing with each variety is arduous and time‐consuming. An alternative is to describe the preference by grazing animals when given a choice of different varieties. Indeed, there is some indications that preference is related to variety characteristics such as leaf content or digestibility, characteristics having also an impact on the level of intake of this variety. However, preference for grass varieties, when sown alone, may not reflect agricultural practice as grasses often occur in mixed swards, associated with white clover. So, the aim of the present work was to determine whether, under grazing management, cattle expressed selections when given a choice of mixed swards in which different perennial ryegrass varieties were grown in association with a common white clover variety at two levels of fertilizer application (60 or 160 kg N ha−1 annum−1). The preference for perennial ryegrass variety per se was then assessed after taking white clover content into consideration. The results show that there were significant differences in preference for perennial ryegrass varieties, per se, even for varieties with the same heading date and ploidy. The effect of white clover cover on sward selection was more marked in swards which received the higher level of nitrogen fertilizer application which may have been related to a more variable white clover content between swards. This suggests that, under low nitrogen fertilizer application, differences in perennial ryegrass varieties preference can be determined in the same experiments as are used to determine ryegrass varieties persistence in association to white clover. Nevertheless, before such ‘variety preference’ tests can be applied in practice, a validation of the possible correlation between ‘variety preference’ and ‘variety intake’ will be necessary.

COMPARATIVE STUDY OF THE AMINOACID’S TRUE DIGESTIBILITY OF DIFFERENT CLOVER (TRIFOLIUM) VARIETIES IN EXPERIMENTS WITH GANDERS

The true digestibility of amino acids of 5 groups of different Trifolium varieties and hybrids was established by using the balance method adapted for geese. Digestibility of the most important amino acids Lysine varies from 70.40 (for tetraplod red clover) to 81.78 (for medium leafy white clover varieties); for Methionine from 60.54 (for Trifolium repens f. giganteum) to 89.42 (diploid red clover); Cystine from 71.03 (for medium leafy white clover) to 87.72 (for Trifolium repens f. giganteum). Amino acids digestibility well correlates with the crude protein content, crude fiber and the total amount of amino acids in the dry matter of the forages and can be predicted with linear regression equations.

고랭지에서 화이트 클로버의 품종별 수량성과 생육특성

본 시험은 화이트클로버 California Ladino(대조품종), Seminole, Sonja, Milo, Rinendel, Alberta 및 Sona 7품종을 축산기술연구소 대관령지소(표고 800m)와 남원지소(표고 450m)에서 각각 난괴법 3반복으로 수행하였다. 화이트 클로버의 엽색은 대조품종 Ladino와 Seminole을 제외하고 모두 연녹색이었고 엽폭도 대형이었다. 내한성은 대조품종인 Ladino 보다 좋은 품종은 Seminole로서 85.2%였다. 화이트 클로버 품종의 건물수량은 대관령에서 대조품종 Ladino보다 많은 Milo와 Rinendel이 남원에서는 대조품종인 Ladino 품종이 우수하였다. 대관령에서 화이트클로버의 품종별 사료가치중 ADF 함량은 대관령과 남원에서 Ladino가 각각 24.3과 23.6%로 가장 낮았고 NDF 함량은 품종간에 큰 차이를 보이지는 않았지만 Sonja, Ladino 및 Rinendel이 낮은 편에 속하였다. 화이트클로버의 조단백질 함량은 대관령지역에서는 Seminole이 가장 높았으며 남원지역에서는 Rinendel이 가장 높았다. 화이트클로버의 조단백질 생산량을 보면 대관령지역에서는 Milo가 가장 높았고 남원지역에서는 Ladino가 가장 높았다. 이상으로 화이트클로버의 건물수량과 사료가치로 미루어 볼때 대관령지역에서는 Milo와 Rinendel이, 남원지역에서는 Ladino와 Seminole이 유망한 품종으로 여겨진다. This study was conducted to select the promising varieties of white clover (va.) California Ladino, Seminole, Sonja, Milo, Rinendel, Alberta and Sona at Daekwanryong branch(altitude 800m a.s.l.) and Namwon branch(altitude 450m a.s.l.) of National Livestock Research Institute. Leaf color of white clover was light green except for Ladino and Seminole, and leaf width was broad in others except for both varieties. Winter hardness of Seminole was the greatest with 85.2%. In Daekwanryong, dry matter yield of white clover was the highest with 5,251kg/ha in Milo of all varieties. Also, dry matter yield of Ladino was the hightest with 9,405kg in Namwon. In Daekwanryong and Namwon, ADF content of Ladino was the lowest with 24.3% and 42.7%, respectively. Also, NDF content of Sonja, Ladino and Rinendel was low when those compared with other varieties. Crude protein content of Seminole in Daekwanryong and Rinendel in Namwon was the highest with 22.2% and 28.4%, respectively. The results of this study indicated that Milo and California Ladino would be the promising varieties of white clover in Daekwanryong and in Namwon. respectively.

Performance of white clover varieties combined in blends and alone when grown with perennial ryegrass under sheep and cattle grazing

Abstract Two experiments were carried out to evaluate the performance of blends of three white clover (Trifolium repens L.) varieties in comparison with the component varieties and three other varieties sown individually in a mixture with perennial ryegrass (Lolium perenne L.). The plots were grazed rotationally in Experiment 1 by cattle and sheep and in Experiment 2 by sheep alone. In both experiments, the blend was composed of three medium‐leaved varieties (AberDai, AberVantage and AberHerald), but with different relative contributions of the three varieties in the two experiments. Dry matter (DM) yields of white clover and perennial ryegrass were assessed in replicate plots for two years (1999 and 2000) after the establishment year. In Experiment 1, there was no significant difference between the DM yields of white clover or perennial ryegrass in either year. The decline in DM yield of white clover between years that was observed for some varieties was not found for the blend. In Experiment 2, significant differences were found in DM yields of white clover in both years. In 1999, AberDai had the highest DM yield. In 2000, AberHerald and AberVantage had the highest DM yields, and AberDai showed a decline in DM yield that was mirrored by the mean for all the white clover varieties. In both experiments, the blend did not show significantly higher DM yield than one or more of its components; indeed, in Experiment 2, it was significantly lower yielding than AberDai in 1999. However, where one component of the blend declined in DM yield between years, this was compensated for by an increase in the yield of another component. These preliminary findings suggest that the yield stability of blends may give them a potential role in agricultural practice.

Long-term performance of white clover varieties grown with perennial ryegrass under rotational grazing by sheep with different nitrogen applications

Three experiments were carried out to investigate the dry matter production of nine white clover (Trifolium repens L.) varieties grown with the same variety of perennial ryegrass (Lolium perenne L.) and subjected to rotational grazing by sheep over a period of 10 years. The experiments differed only in the nitrogen fertilizer added: no nitrogen, 100 kg/ha per year and 200 kg/ha per year. Dry matter (DM) yields of white clover and perennial ryegrass components of the sward were recorded at approximately 6-week intervals during the growing season.Without applied nitrogen, 10-year mean white clover annual DM yields ranged from 2·89–4·54 t/ha. Mean clover content for all varieties ranged from 31–50% for the first 9 years, declining to 20% in the 10th year. The most consistently high yielding variety, AberVantage, gave yields greater than 3·5 t/ha in every year. Similar results were observed for the variety Aran. The 10-year mean annual DM yield of the perennial ryegrass companion (variety Talbot) ranged from 4·41–5·57 t/ha depending on the white clover variety in the mixture. Variation in perennial ryegrass DM yield was of a similar range and pattern as for white clover.In the experiment in which 100 kg N/ha per year was added, 10-year mean white clover annual DM yields ranged from 2·27–3·87 t/ha. The varieties AberVantage and Aran showed yields that fell below 3 t/ha per year in only 1 or 2 years, respectively. Mean clover content for all varieties ranged from 26–38% for the first 9 years, declining to 17·5% in the 10th year. There was no consecutive annual decline in white clover DM yields. The 10-year mean annual DM yields of the perennial ryegrass companion ranged from 6·03–7·57 t/ha.With applied nitrogen fertilizer of 200 kg N/ha per year (Experiment 3), 10-year mean white clover annual DM yields ranged from 1·21–2·67 t/ha. Mean clover content ranged from 12–27% for the 10 years. AberVantage and Aran showed yields consistently above 2 t/ha. No general decline in white clover DM yields was observed although some varieties showed consecutive annual reductions in years 8, 9 and 10. The 10-year mean annual DM perennial ryegrass yields ranged from 7·27–8·68 t/ha.The results show that, under rotational grazing by sheep, white clover can give reliably high yields over a 10-year period. With moderate to high applications of nitrogen fertilizer white clover yields were lower than without nitrogen but they were consistent and sufficient to make a considerable impact on forage quality. There was no evidence for a general decline in clover content until the 10th year of the experiment and no cyclical pattern of annual variation in white clover yield was observed. The implications of these results for the role of white clover in UK agriculture are discussed.

Influence of White Clover Traits on Biomass and Yield in Winter Wheat- or Winter Oilseed Rape-Clover Intercrops

ABSTRACT The potential to use differences in traits of white clover (Trifolium repens L.) varieties to improve mature yield of winter wheat or winter oilseed rape (Brassica napus L.) sown in white clover living mulch was studied in two field experiments conducted in Southern Sweden. The clover varieties Sonja, S184 and AberCrest, differing in leaf size and winter hardiness, were undersown in spring barley. Three consecutive crops of winter wheat or one crop of winter rape sown at two densities followed the barley. In the first year, the mature yields of wheat and high density rape equalled yields without white clover when AberCrest was used, while Sonja reduced the wheat yield by one third and the rape yield to nothing. S184 was intermediate. White clover increased yields by 14–19% in the second wheat crop, but had no effect in the weed infested third wheat crop. The average amount of white clover at flowering of wheat was always largest with Sonja, which increased its biomass earlier in spring than AberCrest. It was concluded that white clover traits are important when developing the intercropping system for large mature yields, especially when herbicides are avoided.

No relationship between leaf size and yield in medium leaf size white clover varieties under rotational sheep grazing and cutting

Nine medium leaf size varieties of white clover (Trifolium repens L.) were grown in field plots with perennial ryegrass (Lolium perenne L.) variety Fennema, and yield measurements were taken under both cutting and rotational sheep grazing. The sampling and management protocols in the cut plots mirrored those for the National List testing of white clover varieties in the UK. Dry‐matter yields of the white clover and perennial ryegrass components of the mixture were recorded for six cuts in each of three harvest years. White clover yields were highest under cutting, perennial ryegrass yields under grazing. Significant differences were seen between the yields of white clover varieties, and significant interactions between white clover yields and management type were also observed. This interaction effect was not seen with respect to perennial ryegrass yields. No correlation was observed between leaf size and white clover dry‐matter yield under either management type. The results suggest that leaf size, on the scale of variation represented within a leaf size category, is not a good predictor of yield under rotational sheep grazing or cutting. The significance of these results for varietal evaluation and for ascertaining the underlying bases for yield differences is discussed.

Relationships between the yield of perennial ryegrass and of small‐leaved white clover under cutting or continuous grazing by sheep

Seven varieties or advanced breeding lines of white clover (Trifolium repens L.), all of small leaf size, were grown separately in mixtures with perennial ryegrass (Lolium perenne L.) in an experiment encompassing three harvest years. Harvestable dry‐matter (DM) yield measurements were taken of these mixtures and of perennial ryegrass monocultures under two management regimes: cutting and continuous sheep grazing. Considerable differences were observed in the harvestable DM yields of white clover, perennial ryegrass and total yields of the mixtures between plots containing different white clover varieties. White clover yields were generally higher under cutting, and perennial ryegrass yields were higher under grazing. The difference between perennial ryegrass yield in monoculture and in mixture was variable. In the second harvest year, a significant interaction effect was seen between management and white clover variety for white clover yield but not for perennial ryegrass yield. The relationship between clover yield and grass yield differed between the two management regimes. Under cutting, a negative correlation was observed, indicative of competitive effects. However, under grazing, no such correlation was seen. Possible mechanisms underlying these outcomes are discussed.

Effect of temperature on growth and morphology of two varieties of white clover (Trifolium repens L.) and their impact on soil microbial activity

Effect of temperature on growth and morphology of two varieties of white clover (Trifolium repens L.) and their impact on soil microbial activity

Contribution of White Clover Varieties in High-Productivity Systems under Grazing and Cutting

Two medium leaf size varieties of white clover (Trifolium repens L.) were grown in mixture with a range of grass species and varieties in a field experiment conducted over 4 years. The clovers were grown singly or as a blend in swards with a tetraploid perennial ryegrass (Lolium perenne L.), a diploid Italian ryegrass (Lolium multiflorum L.) or tetraploid hybrids between these two species (Lolium x boucheanum Kunth). These grasses were also grown in monoculture. Swards were managed in a regime involving two periods of sheep grazing, two periods of cattle grazing and a silage cut in the same year for 4 years. The objectives of this experiment were 3-fold: (1) to examine the yield and persistency of white clover in highly productive systems with modern perennial, hybrid and Italian ryegrasses; (2) to compare the performance of white clover varieties grown singly in mixture with grasses with their performance together as a blend, and (3) to examine the persistency of new Italian ryegrass varieties, exemplified by AberComo. The clover content of the sward remained high throughout the experiment, with a mean of 31 % overall. Differences in clover yield between plots were largely attributable to the effects of companion grasses. Total yields were very similar in plots containing different clover varieties and in plots where these varieties had been grown singly or as a blend. Grass yields in mixture were greater than those in monoculture but showed similar relative rankings. The diploid Italian ryegrass variety AberComo showed an unexpectedly high yield in the 4th year of the experiment. The implications of these results for strategies for productive, sustainable agriculture using modern white clover and ryegrass varieties are discussed. Zusammenfassung Zwei Sorten von Weisiklee (Trifolium repens L.) mit mittlerer Blattgrosie wurden in einer Mischung mit einer Reihe von Grasarten und -sorten in einem Feldexperiment uber vier Jahre untersucht. Klee wurde in Monokultur oder als eine Zumischung in den Bestanden mit tetraploidem Deutschen Weidelgras (Lolium perenne L.), diploidem Welschem Weidelgras Ryegras (Lolium multiflorum L.) oder tetraploiden Hybriden zwischen diesen beiden Arten (Lolium x boucheanum Kunth) untersucht. Die Graser wurden ebenfalls in Reinkultur angebaut. Die Bestande wurden in zwei Perioden durch Schafe und in zwei Perioden von Rindern beweidet sowie mit einem Silageschnitt im gleichen Jahr uber vier Jahre genutzt. Die Ziele der Untersuchung waren dreifach. Zunachst, Ertrag und Persistenz von Weisiklee in hochproduktiven Systemen mit modernen ausdauernden Hybriden und Welschem Weidelgras zu untersuchen. Ferner, die Weisikleesorten in einer Mischung mit Grasern im Hinblick auf ihre Durchsetzungsfahigkeit zu vergleichen und schliesilich die Persistenz von neu entwickelten welchen Weidelgrassorten wie z. B. Abercomo zu untersuchen. Der Kleeanteil der Bestande erhielt sich wahrend des gesamten Experimentes mit einem durchschnittlichen Wert von 31 %. Unterschiede im Kleeertrag zwischen den Untersuchungsparzellen waren uberwiegend den Einflussen der Begleitgraser zuzurechnen. Die Gesamtertrage waren in allen Untersuchungsparzellen mit unterschiedlichen Kleesorten und den Versuchsparzellen mit diesen Sorten im Reinanbau oder in Mischung vergleichbar. Die Grasertrage in den Mischungen waren hoher als im Reinanbau, zeigten aber vergleichbarerelative Ertragsunterschiede. Das diploide Welsche Weidelgras, Abercomo, zeigte unerwartet hohen Ertrag in dem 4-Jahresexperiment. Die Bedeutung dieser Ergebnisse fur Produktionsstrategien in einer ausdauernden landwirtschaftlichen Nutzung mit Weisiklee und Ryegrassorten wird diskutiert.

The Effect of Grazing Intensity on Transition of White Clover Varieties in the Perennial Ryegrass-White Clover Sward

The Effect of Grazing Intensity on Transition of White Clover Varieties in the Perennial Ryegrass-White Clover Sward

Evaluation of seed production potential in white clover (Trifolium repens L. varietal improvement programmes

AbstractThe components of actual and potential seed yield were examined in field experiments on a wide range of varieties of white clover (Trifolium repens L.). The factors affecting seed yield under conditions typical of management regimes used in the production of commercial seed crops were assessed in two experiments. In the first, carried out on spaced plants, considerable diferences are shown between six varieties across the range of leaf sizes in the distribution and profuseness of inflorescence production through the flowering season. In the second, carried out in plots, typical on‐farm criteria were used to choose a single harvest date. Significant variation was found between varieties, including representatives of different leaf size categories, for seed yield components that include number of inflorescences m−2, number of florets per inflorescence and harvestable seed weight. Large‐leaved varieties tended to produce more seeds per floret and higher seed weights per inflorescence, whereas small‐leaved varieties gave the highest number of inflorescences −2. However, the small‐leaved variety AderDale, selected for strong peduncles, was exceptional, giving high values for all seed yield components. The impact of weather conditions on many seed yield components (e.g. total number of inflorescences) was demonstrated by the differences between the 2 years of the experiment. However, other characterstics, e.g. number of florets per inflorescence and number of seeds per floret, did not vary between years. Deviations from potential seed yield were assessed fromthe perspective of commerical seed production. The implications of these results for the production of white clover varieties with increased seed yields under UK conditions are discussed.

Changes in Stolon Carbohydrates During the Winter in Four Varieties of White Clover (Trifolium repensL.) with Contrasting Hardiness

Miniswards of white clover (Trifolium repensL.) varieties Menna, Huia, AberCrest and AberHerald, with contrasting winter hardiness, were established from cloned material in flat boxes. The miniswards were placed in an unheated glasshouse with natural lighting for the winter of 1995/96. During this time there were several periods of cold weather. The plants experienced temperatures at least as severe as those experienced by unprotected plants during preceding mild winters. Growth measurements carried out monthly suggested the cloned genotypes were representative of the varieties from which they were derived. Growth continued throughout the experiment, particularly when expressed as appearance of new internodes. During the coldest weather these internodes were short, and the amount of tissue produced was small. Starch concentration showed a complex pattern of changes during the winter. Older internodes were the major site of starch storage in the autumn; starch was lost from these internodes during the winter and early spring. Starch synthesis also occurred, even during the coldest periods. Starch accumulated in all new stolon tissue. There were significant differences between varieties. AberCrest and AberHerald retained higher concentrations of starch in older stolon tissue, synthesized higher concentrations of starch in young tissue and retained these for longer. There were few differences in soluble sugar concentrations between varieties, but there were significant changes during the winter. In mid-winter, sucrose and pinitol were at their highest concentrations, whereas reducing sugars were at their lowest concentrations. This study further supports the important role of starch reserves in supporting winter survival.

Performance of white clover/perennial ryegrass mixtures under cutting

Clover persistence in mixtures of two varieties of perennial ryegrass (Lolium perenne) with contrasting growth habits and three white clover (Trifolium repens) varieties differing in leaf sizes was evaluated at two cutting frequencies. An experiment was sown in 1991 on a clay soil. The plots received no nitrogen fertilizer. In 1992, 1993 and 1994, mixtures containing the large‐leaved clover cv. Alice yielded significantly more herbage dry matter (DM) and had a higher clover content than mixtures containing cvs Gwenda and Retor. Companion grass variety did not consistently affect yield or botanical composition. Cutting at 2 t DM ha−1 resulted in slightly higher total annual yields than cutting at 1.2 t DM ha−1, but did not affect clover content. In 1992 the mixtures yielded, depending on cutting frequency and variety, 10·6–14·6 t DM ha−1 and 446–599 kg ha−1 N, whereas grass monocultures yielded only 1·2–2·0 t DM ha−1 and 25–46 kg ha−1 N. From 1992 to 1994 the annual mean total herbage yield of DM in the mixtures declined from 12·2 to 10·5 to 8·7 t ha−1, the white clover yield declined from 8·7 to 6·5 to 4·1 t ha−1 and the average clover content during the growing season declined from 71% to 61% to 46%, whereas the grass yield increased from 3·4 to 4·0 to 4·5 t ha−1. The N yield decreased from 507 to 406 to 265 kg N ha−1 and the apparent N fixation from 470 to 380 to 238 kg N ha−1. Nitrate leaching losses during the winters of 1992–93 and 1994–95 were highest under mixtures with cv. Alice, but did not exceed 10 kg N ha−1. The in vitro digestible organic matter (IVDOM) was generally higher in clover than in grass, particularly in the summer months. No differences in IVDOM were found among clover or grass varieties. The experiment will be continued to study clover persistence and the mechanisms that affect the grass/clover balance.

Performance of white clover/perennial ryegrass mixtures under cutting

Clover persistence in mixtures of two varieties of perennial ryegrass (Lolium perenne) with contrasting growth habits and three white clover (Trifolium repens) varieties differing in leaf sizes was evaluated at two cutting frequencies. An experiment was sown in 1991 on a clay soil. The plots received no nitrogen fertilizer. In 1992, 1993 and 1994, mixtures containing the large-leaved clover cv. Alice yielded significantly more herbage dry matter (DM) and had a higher clover content than mixtures containing cvs Gwenda and Retor. Companion grass variety did not consistently affect yield or botanical composition. Cutting at 2 t DM ha−1 resulted in slightly higher total annual yields than cutting at 1.2 t DM ha−1, but did not affect clover content. In 1992 the mixtures yielded, depending on cutting frequency and variety, 10·6–14·6 t DM ha−1 and 446–599 kg ha−1 N, whereas grass monocultures yielded only 1·2–2·0 t DM ha−1 and 25–46 kg ha−1 N. From 1992 to 1994 the annual mean total herbage yield of DM in the mixtures declined from 12·2 to 10·5 to 8·7 t ha−1, the white clover yield declined from 8·7 to 6·5 to 4·1 t ha−1 and the average clover content during the growing season declined from 71% to 61% to 46%, whereas the grass yield increased from 3·4 to 4·0 to 4·5 t ha−1. The N yield decreased from 507 to 406 to 265 kg N ha−1 and the apparent N fixation from 470 to 380 to 238 kg N ha−1. Nitrate leaching losses during the winters of 1992–93 and 1994–95 were highest under mixtures with cv. Alice, but did not exceed 10 kg N ha−1. The in vitro digestible organic matter (IVDOM) was generally higher in clover than in grass, particularly in the summer months. No differences in IVDOM were found among clover or grass varieties. The experiment will be continued to study clover persistence and the mechanisms that affect the grass/clover balance.

Breeding and evaluation of new white clover varieties for persistency and higher yields under grazing

AbstractTwo experiments were established in 1989 and 1990 to evaluate the performance of white clover (Trifolium repens) varieties under grazing, using sheep and cattle, and also under a ‘cutting‐only’ regime. The three potential medium/large‐leaved varieties (AberVantage, AberCrown and AberDai) were selected and evaluated in a breeding programme that emphasized improving yield and persistency under grazing.In Experiment 1, the potential varieties were sown with two different grass companions, and evaluated under a continuous cattle‐grazing system, representative of their future role in actual farm practice, i.e. a set stocking system. Clover yield of the potential varieties in the second harvest year averaged 1–5 t ha−1 more than the control variety Olwen. Total sward production of AberVantage, AberCrown and AberDai was 2.0–1.4 t ha−1 higher than that of Olwen.In Experiment 2, clover yields of the three potential varieties averaged 2.1 t more than Olwen in the second harvest year under continuous sheep grazing, but all three were lower yielding than Olwen in the cutting regime.Both experiments illustrate how the use of grazing treatments during breeding and evaluation can improve the role of white clover varieties.

Effects of sward type and rest periods from sheep grazing on white clover presence in perennial ryegrass/white clover associations

AbstractThe effects of the imposition and timing of a rest period from continuous sheep stocking, for a conservation cut, on white clover presence in forty perennial ryegrass/white clover associations were studied over two full grazing seasons. Each association consisted of one grass variety along with one white clover variety, the grasses being diploid and tetraploid ryegrasses from each of five maturity groups and the white clovers from each of four leaf size categories. The presence of white clover within each association was assessed at the beginning and end of both seasons by means of a 0–64‐m2 quadrat subdivided into 100 squares, each 80 mm × 80 mm, the number of squares in which any part of a white clover plant was visible being recorded. Complementary point quadrat data were also collected.Although continuous sheep stocking did not necessarily have an adverse effect on white clover presence, a July to mid‐August rest period increased white clover proportions in the swards (means: unrested, 48–1; April to late May rest, 32.7; July to mid‐August rest, 67.3 ‐ s.e.d. 7.59; P < 0.05) the benefit increasing with increasing white clover leaf size. The early rest period (April to late May) reduced white clover presence and the late rest period (July to mid‐August) increased white clover presence, these effects being intensified with increasing white clover leaf size (very large‐leaved clover: unrested, 20.6; April to late May rest, 8.3;July to mid‐August rest, 41.1 and small‐leaved clover: unrested, 96.3; April to late May rest, 84.8; July to mid‐August rest, 97 ‐ s.e.d. 9.2; P <0001). Tetraploid ryegrass/white clover associations had consistently and significantly more white clover than diploid ryegrass/white clover associations of similar ryegrass maturity group (tetraploid, 53.4; diploid 44.8 ‐ s.e.d. 2.12; P <0.001) and associations with early maturing ryegrass contained more white clover than those with late maturing ryegrasses, the effect of maturity group being greater than that of ploidy. Overall, white clover presence increased with increasing openness of grass growth habit.

Peduncle characteristics, inflorescence survival and reproductive growth of white clover (Trifolium repens L.)

AbstractField experiments were carried out in four harvest years to compare the peduncle characteristics and reproductive growth of the small‐leaved white clover (Trifolium repens L.) cv. AberDale, selected for long and strong peduncles, with other varieties bred in the Institute of Grassland and Environmental Research (IGER). The peduncles of cv. AberDale were of larger diameter and had a greater fresh and dry weight than those of other varieties. There were also differences in structure as the peduncles of cv. AberDale had more pronounced ridges and furrows than those of cv, Menna.Inflorescences of cv. AberDale and other varieties were tagged when in full bloom throughout the flowering period in each of the four harvest years. Generally, more inflorescences of cv. AberDale remained intact until harvest, particularly from the early tagging dates. Although there were seasonal differences, at harvest in each of the 4 years, cv. AberDale had more inflorescences and seeds per floret and a greater potential seed yield than the other varieties.The basis of peduncle strength and effect on reproductive growth is discussed, and the implications for improving the seed yield potential of white clover varieties is considered.