An assessment of the cultural capabilities of Trifolium repens L. (white clover) and Onobrychis viciifolia Scop. (sainfoin) mesophyll protoplasts

Mesophyll protoplasts isolated from white clover and sainfoin divided to form callus under similar cultural conditions. White clover protoplasts showed varietal differences in their plating efficiency. Sainfoin tissues regenerated readily by forming shoots, but induction of morphogenesis in white clover was only achieved after testing several media and culture sequences. Many of the white clover shoots were abnormal in being fused together to form green plate-like structures, but the latter still developed into plantlets while attached to the parent callus. The ability to isolate, culture, and regenerate mesophyll protoplasts of these two forage legumes is discussed in relation to future attempts to produce somatic hybrids between high tannin containing bloat-safe sainfoin and other major forage legumes such as alfalfa, white clover, and red clover.     

The absorption and transport of manganese by perennial ryegrass and white clover as affected by silicon

Summary The effects of added silicon on the absorption and transport of manganese in perennial ryegrass (an accumulator of Si) were determined and compared with those found in white clover (which has restricted Si uptake). The plants were grown in flowing solution culture in two experiments with Si in the nutrient solution maintained at 0, 10 or 20 mgl⁻¹ and Mn at 0.005 mgl⁻¹. By the final harvests, the plants contained concentrations of both Mn and Si that were comparable to those found in field-grown plants. In common with other findings, white clover had very much lower concentrations of Si in both shoots and roots than did ryegrass but there was no effect of Si treatment on the growth of either species. In both species, the concentrations of Mn were initially greater in roots than in shoots, but values in both plant parts decreased with time and by the final harvests, were similar. The rates of absorption of Mn by roots and its subsequent transport to shoots were also similar in both species. In contrast to findings for other species in other studies based on conventional solution culture, there was no effect of added Si on either absorption or transport of Mn in clover or ryegrass. It was therefore concluded that any effect of Si on the behaviour of Mn in plants must result from changes in distribution and partitioning within leaf tissues and cells.     

Absorption and Distribution of Copper in Plants with Sufficient or Deficient Supplies

Wheat, red clover and ryegrass were grown in flowing solutionculture with sufficient (+ Cu) and deficient (–Cu) suppliesof copper. The rates of Cu absorption (µg g^–1 dryroot day^–1) did not differ greatly between species ineither treatment. Wheat plants, when transferred from the –Cu to the +Cu treatment, absorbed Cu at a much slower rate thanthose which had remained throughout in the + Cu treatment. Inall plants considerable proportions of the absorbed Cu wereretained in the roots, even when the plants were Cu-deficient,and the concentration in roots usually exceeded that in anypart of the shoots in both treatments. Transferring wheat plantsfrom the +Cu to the –Cu treatment decreased the concentrationin all plant parts except old leaves; similarly, transferringfrom the –Cu to +Cu treatment increased the concentrationin all parts of the shoots, execept old leaves, and in the roots. Lolium perenne, Trifolium pratense, Triticum aestivum, ryegrass, red clover, wheat, absorption, copper, flowing solution culture     

Sodium Absorption and Distribution in Forage Grasses of Different Potassium Status

The absorption and distribution of sodium were examined in threegrasses grown in flowing solution culture with different suppliesof potassium. There were marked differences between the speciesin the rate of absorption by their roots, timothy absorbingat a much slower rate than either ryegrass or cocksfoot. Inall species, the rate of Na absorption was greatest when therewas a maintained supply of K and/or when the K contents of theplants were high. Transport of Na from roots to shoots of timothywas restricted; it was less restricted in the other speciesand large proportions of the Na moved from roots to shoots whenK was not supplied to the plants. Sodium transported from theroots accumulated in old leaves and not in the younger leaves.When K was no longer supplied, the growth of ryegrass was maintainedin the plants previously grown with Na plus K; Na supplied insteadof K, however, did not maintain growth. Cocksfoot grown withNa grew less well than when grown without Na when plants wereno longer supplied with K; the growth of timothy was unaffectedby Na. Dactylis glomerata L., Lolium perenne L., Phleum pratense L., cocksfoot, ryegrass, timothy, absorption of ions, distribution of ions, potassium, sodium     

THE MUTUAL EFFECT OF RYEGRASS AND CLOVER WHEN GROWN TOGETHER

Italian ryegrass and a late-flowering red clover were grown together, with abundance of water and nutrients for both. It was found that even a small number of ryegrass plants reduced the growth of clover by 30%. This effect varied very little with increasing density of the clover crop.
The presence of clover reduced the ryegrass crop by an amount diminishing as the density of the ryegrass was increased. In a sparse crop of ryegrass, clover reduced the growth of the grass considerably more than did barley under comparable conditions.
There is no evidence of any specific effect of the roots of one plant on the other. When ample nitrogen is available the clover tends to take some that would otherwise be available for the grass and does not provide the grass with additional nitrogen.     

Preference of dairy cows for ryegrass, white clover and red clover, and its effects on nutrient supply and milk quality

Two experiments were conducted with 30 dairy cows each, to study the preference for fresh (Experiment 1) and ensiled (Experiment 2) ryegrass, white and red clover. Both experiments consisted of three choice diets with white or red clover or both, offered with ryegrass, and two diets with ryegrass mixed with white or red clover (40% clover). Cows consumed diets with 37.7% fresh white and 45.9% red clover, and no preference was observed when the cows were offered all three forages. By contrast, cows preferred white and red clover silage (73.0 and 69.2%, respectively) over ryegrass silage (of lower nutritive quality). When offered three forages, cows preferred white (59.8%) over red clover (17.5%) and ryegrass (22.7%). Choice diets resulted in diets similar (fresh forages) or higher in nutrient content and digestibility (silages). Treatments did not affect feed intake and performance. Choices compared to mixed diets with red clover silage were preferable regarding the fatty acid composition of the milk fat. Obviously, only large differences in nutrient and energy concentration facilitate preferences for clovers over ryegrass, which could, depending on clover type, be beneficial in terms of the milk's fatty acid composition.     

The influence of water supply on the growth and phosphorus uptake of italian ryegrass and white clover in pot culture

Summary White clover appears to be much more sensitive, in terms of dry-matter production, to variations of soil moisture than Italian ryegrass. The results show that a variation of 5 in the percentage of water (moist-soil basis) on either side of the field-capacity figure can cause a statistically significant effect in the dry weight of Italian ryegrass in pot culture, although a slightly larger percentage may be necessary for white clover to be affected as standard errors in pot culture with this crop tend to be higher.With an adequate supply of soil phosphorus the greater the amount of readily available water the greater the percentage of P₂O₅ in Italian ryegrass; with white clover it rises to a maximum then falls off under very wet Statistically significant differences in percentage P₂O₅ for both crops can be obtained whit those variations in the water supply which caused significant differences in dry weight.     

The effects of mixing Italian ryegrass (Lolium multiflorum) with perennial ryegrass (L. perenne) or red clover (Trifolium pratense) on the incidence of viruses

Mixing the ryegrass mosaic virus (RMV) resistant perennial ryegrass (Lolium perenne) cv. Endura with the susceptible Italian ryegrass (L. multiflorum) cv. RvP decreased infection of RvP wth RMV from 37% when grown alone to 22% when mixed. However, Endura yielded less than RvP and there was no yield benefit from mixing the two cultivars. Mixing red clover (Trifolium pratense) cv. Hungaropoly with RvP had no detectable effect on RMV incidence in RvP but did decrease the incidence of red clover necrotic mosaic virus in Hungaropoly from 9% to 1% and of white clover mosaic virus from 53-5% to 41%. The yield of the mixture was equal to that of RvP grown alone but given nitrogen fertiliser. The numbers of eriophyid mites, including Abacarus hystrix the vector of RMV, on ryegrass leaves were similar in pure and mixed swards. It is concluded that with herbage crops, the common practice of sowing mixtures of species may help control virus diseases.     

Root turnover in pasture species: chicory,lucerne, perennial ryegrass and white clover

For pastures, root turnover can have an important influence on nutrient and carbon cycling, and plant performance. Turnover was calculated from mini‐rhizotron observations for chicory (Cichorium intybus), lucerne (Medicago sativa), perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) grown in the Manawatu, New Zealand. The species were combined factorially with four earthworm species treatments and a no‐earthworm control. Split plots compared the effects of not cutting and cutting the shoots at intervals. Observations were made c. 18 days apart for 2.5 years. This article concentrates on differences between plant species in root turnover in the whole soil profile to 40 cm depth. At this scale, earthworm effects were generally small and short lived. For ryegrass and white clover, root length and mass were linearly related (R² = 0.82–0.99). For chicory and lucerne, the relationships were poorer (R² = 0.38–0.77), so for those species length turnover may be a poor indicator of mass turnover. Standing root length, total growth and death generally decreased in the sequence ryegrass > lucerne > chicory = white clover. In length terms, scaled turnover (growth divided by average standing root length) generally followed the sequence lucerne > white clover > perennial ryegrass = chicory. Across species the scaled turnover rate averaged 3.4 per year or 0.9% per day. Cutting shoots reduced standing root length, growth and death, but increased scaled turnover. These results indicate fast and prolonged root turnover. For ryegrass and white clover, at least there is need to reappraise how to measure and model shoot : root ratios, dry matter production and carbon cycling.     

Cd对不同种类植物生长和养分积累的影响

溶液培养法研究了不同活度Cd2 对4种植物卷心菜、黑麦草、玉米和白三叶草生长和养分积累的影响．结果表明,随Cd2 活度增加,4种植物的生长速率和干物质产量均下降．白三叶草对Cd2 最敏感;黑麦草和玉米耐性较强;卷心菜在高ACd2 时敏感．Cd2 对Fe、Mn、Cu、Zn、Ca、Mg、P、S等养分积累的影响因植物种类而异．Cd2 降低Fe、Mn、Cu、Zn、Ca、Mg等的积累．P在4种植物中和S在除卷心菜外的3种植物中的积累比对照增加．卷心菜和白三叶草对Cd毒敏感性差异与Fe、Mn、Ca、Mg的积累受Cd2 影响程度不同密切相关．     

Growth of zinnia,Italian ryegrass,and alfalfa and their remediation effects in diesel oil-contaminated soils

Abstract

Our objective in this study was to compare the growth of zinnia, Italian ryegrass, and alfalfa, and their remediation effects in oil-contaminated soils. The soils were prepared by mixing 2, 4, or 8% diesel oil by weight with soil. The plant height and dry weights of shoots and roots were highest for zinnia in the 2 and 4% oil treatments, and highest for Italian ryegrass in the 8% oil treatment. The reduction ratios in soil total petroleum hydrocarbons concentration (TPH) for 3 plants were lower in the 4 and 8% oil treatments than those in the 2% treatment. The reduction ratios for Italian ryegrass and zinnia contaminated with 2, 4, and 8% diesel oil treatments were significantly higher than those for alfalfa and the non-cultivation treatment at 45?days after sowing, and there were no significant differences in reduction ratios between Italian ryegrass and zinnia. The reduction ratio of soil TPH concentration brought about by zinnia was also comparable to that of Italian ryegrass. Therefore, we conclude that zinnia shows growth and remediation effects that are equivalent to those of Italian ryegrass, in soils contaminated with less than 8% oil.     

Some soil-plant and root-shoot relationships of copper,zinc and manganese in white clover and perennial ryegrass

Summary White clover and perennial ryegrass were grown separately, in pots maintained under controlled environment conditions, for a period of 7 months on ten soils. The proportion of the total soil content of each element taken up by the ryegrass, including that in roots, ranged from 0.88 to 2.18% for Cu, from 0.82 to 2.80% for Zn and from 0.25 to 3.15% for Mn. Uptake by the clover was within these ranges for Cu and Zn, but ranged from 0.10 to 1.71% for Mn.After adjustment for the effects of soil contamination, the ratio of root concentration: shoot concentration was always greater than 1 for both Cu and Zn, and for Cu, though not for Zn, it was considerably greater with ryegrass than with clover. For Mn, the ratio of root:shoot concentration was often greater than 1, and differences between clover and grass were not consistent.Concentrations of Cu and Zn in the shoots were always greater in the clover than in the grass, but concentrations of Mn were generally greater in the grass than the clover.     

Patterns of 14C-labelled Assimilate Partitioning in Red and White Clover During Vegetative Growth

A quantitative analysis of the ¹⁴C-labelled assimilate suppliedby the expanded leaves on the primary shoot to growing leaves,stem, lateral shoots (branches or stolons) and roots in redand white clover was conducted during vegetative growth. Stem growth of the primary shoot was inhibited in both cloversand utilized no energy resources. The growing leaves at theprimary shoot apex of white clover imported 4 per cent of theshoot's assimilate compared with 10 per cent in red clover.At the basal end of the primary shoot, the tap root of whiteclover imported 16 per cent of the shoot's assimilate comparedwith 22 per cent in red clover. Branches in red clover and stolonsin white clover were by far the largest sinks for primary shootassimilate, importing 39 per cent and 63 per cent of the labelledassimilate, respectively. Analyses of the translocation of assimilate from individualprimary shoot leaves demonstrated that in both clovers olderleaves exported more of their assimilate to branches or stolons,whereas younger leaves exported more of their assimilate toroots, and possibly in white clover, to growing leaves at thetip of the shoot. Of the labelled assimilate exported to branchesor stolons, each primary shoot leaf exported preferentiallyto the branch or stolon in its own axil, but in addition exportedsubstantial quantities of assimilate to all other axillary shoots,particularly those arising from basal axils where the subtendingleaf had died. Trifolium repens, Trifolium pratense, red clover, white clover, assimilate partitioning, perennation     

模拟降雨下草地植被调控坡面土壤侵蚀过程

采用人工模拟降雨的方法,定量研究了黄土高原地区不同生长阶段黑麦草(Lolium perenne L.)和红豆草(Onobrychis viciaefolia Scop.)及裸地坡面的降雨产流产沙过程,并通过降雨前剪掉冠层的方法对比分析了两种牧草根系与冠层在减少坡面径流与侵蚀产沙中的贡献率。试验结果表明:与裸土坡面相比,两种牧草都能有效的控制坡面土壤侵蚀,在试验末期黑麦草和红豆草的减流效益分别为65%和45%,而两者的减沙效益均在93%以上。两种牧草根系与冠层减少坡面径流与泥沙贡献率存在一定的差异,黑麦草冠层比根系具有更大的减流贡献率,除最后试验阶段冠层减流贡献率为44.7%外,在其他试验阶段黑麦草冠层的贡献率大于60%。相反,红豆草对坡面径流的减少则主要依赖于根系的作用。植物根系在控制坡面土壤侵蚀产沙中发挥着很大的作用。从实验初期到实验末期,黑麦草和红豆草根系的减沙贡献率分别由72%和16%增加到96%和93%。     

Root exudates: a pathway for short-term N transfer from clover and ryegrass

The short-term transfer of nitrogen (N) from legumes to grasses was investigated in two laboratory studies. One study was done in pots where the roots of white clover (Trifolium repens L.) and perennial ryegrass (Lolium perenne L.) were allowed to co-exist, and a second study was performed using a micro-lysimeter system designed to maintain nutrient flow from the clover to the grass, whilst removing direct contact between the root systems. The ¹⁵N-dilution technique was used to quantify the transfer of N between species. Levels of ammonia and amino acids were measured in root exudates. The amounts of N transferred were in the same order of magnitude in both the pot and micro-lysimeter experiments. In the micro-lysimeter experiment, 0.076 mg of N were transferred per plant from clover to ryegrass during the course of the experiment. Ammonium exudation was much higher than amino acid exudation. The most abundant amino acids in both clover and ryegrass root exudates were serine and glycine. However, there was no correlation between the free amino acid profile of root extracts and exudates for both plant species: Asparagine was the major amino acid in clover roots, while glutamine, glutamate and aspartate were the major amino acids in ryegrass roots. Comparison of exudates obtained from plants grown in non-sterile or axenic conditions provides evidence of plant origin of ammonium, serine and glycine.     

Lipid metabolism in mixtures of red clover (Trifolium repens) and perennial ryegrass (Lolium perenne) in lab scale silages and in vitro rumen incubations

Most often, farmers consider red clover an unattractive forage because of its low ensilability. Nevertheless, several in vivo and in vitro experiments also showed advantages of red clover silages such as decreased rumen biohydrogenation of polyunsaturated fatty acids. This has been attributed to a possible protective role of protein-bound phenols, with polyphenol oxidase playing a key role in their formation. This enzyme is active in red clover, but not in other green forages, such as, for example, perennial ryegrass. Therefore, the aim was to study the lipid metabolism within red clover/ryegrass mixtures in lab scale silages and during in vitro rumen batch incubations. Ensilability of red clover increased with higher proportions of ryegrass in the silage mixture. However, the lipid-protecting mechanism of red clover does not seem to occur in the co-ensiled ryegrass as lipolysis of polar lipids linearly increased with increasing proportions of ryegrass (86.0%, 91.6%, 89.9%, 93.1% and 95.6% in 60-day-old silages with 100/0, 75/25, 50/50, 25/75 and 0/100 red clover/ryegrass, respectively). Rumen lipolysis and biohydrogenation of C18:3n-3 and C18:2n-6 were negatively related to red clover proportions in the silage mixtures. The lipid-protective mechanism in red clover silages is confirmed, but it seems not to be transferred to lipids in co-ensiled forages.     

The effect of sulfur supply on the root characteristics of subterranean clover and annual ryegrass

Summary The root characteristics and sulfur absorption of Trikkala sub-clover and Wimmera ryegrass were compared in a pot experiment in which plants were grown at two levels of sulfur supply (0 and 64 mgS/pot) for a period of 40 days after emergence.Ryegrass roots had a greater weight and root weight ratio, but a lower sulfur content than sub-clover roots at both levels of sulfur supply. Ryegrass roots were longer, had a greater length per unit weight, longer root hairs, and hence a larger volume and surface area than sub-clover roots. However, when the sulfur content in the whole plant was related to the root parameters, sub-clover absorbed a far greater amount of sulfur, irrespective of whether the content was expressed on the basis of the weight, length, volume or surface area of the roots.Sulfur application had relatively little effect on the morphology of roots of either species. However, whilst sulfur application increased the weight of both shoots and roots, it decreased the root weight ratio for sub-clover but not for ryegrass. Increasing sulfur supply reduced the total length of sub-clover roots but tended to increase the length of ryegrass roots. For both species, the length per unit weight of roots decreased, and the average root diameter increased, with increasing sulfur supply. Sulfur application decreased the volume and surface area of sub-clover roots, but increased these parameters in ryegrass roots.     

氮锌硒肥配合施用对白三叶的固氮作用与氮转移的影响

在湖北省宜昌县百里荒草场山地黄棕壤上配合施用氮锌硒肥,研究其对混播白三叶,混播黑麦草及单播黑麦草的干重及混播白三叶的固氮作用和氮转移的影响,试验结果表明：（1）氮锌硒肥配合施用,混播黑麦草的干重均高于相应处理的单播黑麦草,混播牧草和单播黑麦草重最高的处理都是N46Zn0Se5,其干重辚25．38 g／盆和19．93g/盆。（2）施氮对混播白三叶,混播黑麦草及单播黑麦草的生长有明显的促进作用,施锌,硒对混播白三叶,混播黑麦草及单播黑麦草的生长作用不明显。（3）混播白三叶氮素的主要来源是固氮作用,占全氮产量的57．6000％－77．258％。（4）混播白三叶固定氮的转移量只占混播黑麦草的全氮产量的0．316％－12．251％,通过正交方差分析发现,适量氮肥（N30mg/kg)促进固定氮的转移,高量氮肥（N46mg/kg)抑制固定氮的转移。     

Potential phosphorus release from catch crop shoots and roots after freezing-thawing

Background and aims

Catch crops used for mitigating nutrient losses to water can release phosphorus (P) when exposed to repeated freezing-thawing cycles (FTCs). This study sought to evaluate potential P losses from shoots and roots of eight catch crops.

Methods

Shoots and roots sampled from perennial ryegrass (Lolium perenne L.), cocksfoot (Dactylis glomerata L.), chicory (Cichorium intybus L.), phacelia (Phacelia tanacetifolia L.), red clover (Trifolium pratense L.), white mustard (Sinapis alba L.), oilseed radish (Raphanus sativus var. oleiformis L.) and white radish (R. sativus var. longipinnatus L.) were treated with no freezing, one single FTC, four continuous FTCs and four discontinuous FTCs. All samples were analysed for water-extractable P (WEP), and root samples also for characteristics such as specific root surface area (SSA).

Results

Freezing-thawing significantly increased potential P losses from both shoots and roots compared with no freezing. The two radish species and white mustard contained significantly higher concentrations of WEP than the other species, among which chicory and phacelia had the lowest WEP. On average, shoots had 43 % higher WEP than roots. Cumulative P release from shoots and roots was strongly correlated with their total-P content (p?=?0.006 and p?=?0.002, respectively). Cumulative release of P from taproots was correlated with SSA (p?=?0.03).

Conclusions

Chicory, and possibly phacelia, appear to be promising catch crops for P.     

Below-ground nitrogen transfer between different grassland species: Direct quantification by 15N leaf feeding compared with indirect dilution of soil 15N

Nitrogen (N) transfer from one species to another is important for the N cycling in low-input grassland. In the present work, estimates obtained by an indirect ¹⁵N dilution technique were compared with estimates obtained by a direct ¹⁵N leaf feeding technique over two complete growing seasons in red clover-ryegrass and white clover-ryegrass mixtures under field conditions. The direct technique confirmed that N transfer between clovers and ryegrass is a bi-directional process. The transfer of N from both clovers to ryegrass occurred within 25 days upon the first labelling event. A very high N transfer occurred from white clover to the associated ryegrass, 4.5 and 7.5 g m⁻² in the 1st and 2nd production year, respectively. The corresponding values for transfer from red clover to the associated ryegrass were 1.7 and 3.6 g m⁻². Quantified relatively to the total above-ground N content of white clover- ryegrass and red clover-ryegrass mixtures, the N transfer exceeded 50% and 10%, respectively, in three out of seven harvests. The N transfer from ¹⁵N labelled grass to associated clovers constituted a relatively constant proportion of approx. 8% of the above-ground N content of the mixtures. Estimates based on the soil ¹⁵N dilution technique generally underestimated the net N transfer by more than 50% compared to the direct ¹⁵N labelling technique. Furthermore, the indirect ¹⁵N dilution technique estimated only marginal differences between red and white clover in the quantities of N transferred, whereas the direct ¹⁵N labelling technique showed the N transfer from white clover to the associated ryegrass to be significantly higher than that involving red clover. It is concluded that N transfer is a much more dynamic and quantitatively important process in grassland than previously recognised. This revised version was published online in June 2006 with corrections to the Cover Date.