Growth Of White Clover Research Articles

The Influence of Natural Canopy Density on the Growth of White Clover, Trifolium repens

Two genotypes of white clover, Trifolium repens, were propagated clonally and grown under grass or woodland canopies. Canopy densities varied such that they transmitted a complete range (0 to 100%) of the available photosynthetically active radiation (PAR). As % PAR decreased (i.e. with more shading) the development of branches was suppressed, and internode and petiole elongation increased. In general, however, the responses were non-linear, and elongation of internodes and petioles decreased again at the lowest values of % PAR. The genotype from the open habitat was, in general, more sensitive to variations in % PAR under lower light conditions. It reached maximum internode and petiole elongation under higher light conditions than did the genotype from the more shaded habitat (...)

Growth and persistence of perennial ryegrass and white clover direct-drilled into a paspalum-dominant dairy pasture treated with glyphosate

Abstract Paspalum-dominant pastures suffer from poor winter/spring herbage production, which can be corrected by direct-drilling cool-season-active species such as ryegrass. The growth and persistence of perennial ryegrass (Lolium perenne L.) and white clover (Trifolium repens L.) direct-drilled into a paspalum (Paspalum dilatatum Poir.)-dominant, rotationally grazed dairy pasture, and their effects on production, were studied over 5 years. Treatments were original pasture (control) and herbicide treatment with 0, 0.72, 1.44, and 2.16 kg a.i./ha of glyphosate (Roundup® herbicide, 36% glyphosate) before direct-drilling. Observations on tagged ryegrass and white clover plants found establishment plant numbers for ryegrass were 74% higher (788 plants/m2) in herbicide-treated than in untreated areas (452 plants/m2). Half of all tagged ryegrass plants disappeared in the first year after which losses were much reduced. The establishment and survival of tagged white clover plants were poor. Paspalum gradually re-infested the herbicide-treated areas and by the end of the fourth year had reached pretreatment levels of 30–40% of dry matter (DM). Application of glyphosate before drilling produced a 38% increase in winter/spring herbage accumulation in the first year, but this advantage declined and was non-significant by the end of the fourth year.

Response to re-application of phosphate fertilisers on hill pasture where fertiliser had been withheld for seven years

A field experiment at the AgResearch Te Kuiti Research Area examined effects of re-application of phosphorus (P) fertilisers on production and composition of hill pastures (1520% slope) which had received no P for 7 years. Treatments were 0, 20, 40 and 80 kg P/ha/year as single superphosphate (SSP) or North Carolina reactive phosphate rock (RPR). The soil was a yellowbrown earth/yellow-brown loam intergrade with Olsen P 9. Re-application of P produced a rapid and large increase in pasture production of up to 42 and 61% in years 1 and 2, respectively, and brought production up to 95% of that measured in neighbouring regularly fertilised paddocks. The pasture response to RPR was less (PcO.01) than that to SSP in both years, particularly at the highest rate. This indicated that RPR was less suitable for capital application. The P response was due almost entirely to an increase in white clover growth, and N, fixation was estimated to increase from 30 to 130 kg N/ha/year. In year 2, there was an increase in ryegrass content of pasture receiving the high P rate and this was attributed to increased nitrogen availability due to increased N, fixation. Keywords: hill country, phosphorus, reactive phosphate rock, superphosphate

The effects of sward height and nitrogen fertilizer application on changes in sward composition, white clover growth and the stock carrying capacity of an upland perennial ryegrass/white clover sward grazed by sheep for four years

AbstractPerennial ryegrass/white clover pastures grazed by sheep and receiving either no fertilizer N (No) or 120 kg N ha−1 year−1 (N0) were maintained with surface heights of 2·5, 3·5 and 5·0 cm for over four years. The treatments were replicated.The white clover (WC) population was greatest in the N0treatment, and declined during the study. Between‐year variation in WC was negatively related to rainfall and positively related to temperature, WC as a proportion of the total plant population decreased during the summer in the Nl treatment. The perennial ryegrass (PRG) population was greater in the Nl treatment, declined during the study and both within and between years was positively related to temperature. The population density of the unsown grasses was highest in the N‐fertilized treatment and in the swards maintained at the lowest heights (these treatments also had the highest stocking rate); it increased during the study, within‐years being positively related to temperature and between‐years being positively related to rainfall.The WC stolon extension rate was largely unaffected by N fertilizer application and was greatest in the taller swards. Leaf appearance rate was unaffected by N fertilizer application and sward height; it was positively related to temperature and negatively related to rainfall.Branching rate was greater in the N0 treatment with significant sward height effects confined to a negative relationship with local sward height within treatment plots on one occasion; it was negatively related to rainfall. The ground level red:far red light ratio was negatively related to local sward height. The total live weight of sheep carried in the No treatments was 0·7 of that in the N1 treatments.Expected photomorphogenic responses by we were confined to stolon extension. It was concluded that on the poorly drained clay‐loam soil used in this study the effects of sheep, in interaction with climatic factors, had an overriding effect on clover branching rate and the ultimate species composition.

Growth of White Clover, Dependent on N2 Fixation, in Elevated CO2 and Temperature

Clonal plants of white clover (Trifolium repens L.), wholly dependent on N 2 fixation, were grown for 6 weeks in controlled environments providing either (C680 regime) 23/18 o C day/night temperatures and a CO 2 concentration of 680 μmol mol -1 , or (C340 regime) 20/15 o C day/night temperatures and a CO 2 concentration of 340 μmol mol -1

Influence ofAcremonium loliiinfection in perennial ryegrass on germination, emergence, survival, and growth of white clover

Abstract Four glasshouse experiments and two field trials were conducted to determine the effects of perennial ryegrass (Lolium perenne L.) infected with Acremonium lolii Latch, Christensen & Samuels on white clover (Trifolium repens L.) germination, emergence, growth, and survival. Under controlled laboratory experiments, ryegrass leachates temporarily inhibited the rate of white clover germination, but did not affect white clover emergence or yield. In glasshouse experiments, the presence of A. lolii did not influence white clover emergence or growth. Emergence of indicator plant species grown in pumice sand substrate which previously grew ‘Ellett’ or ‘Grasslands Nui’ perennial ryegrass was not affected (‘Ellett’) or was enhanced (‘Grasslands Nui’) by the presence of A. lolii. In field trials, A. lolii infection did not significantly affect white clover survival, vigour, or leaves and stolons per plant, when ryegrass tiller densities were similar. Later, when tiller density of A. lolii-free plants decre...

The Growth and Carbon Allocation Patterns of White Clover (Trifolium repens L.) Plants of Contrasting Branching Structure

The growth, morphology and carbon allocation patterns of F1 progeny white clover (Trifolium repens L.) plants selected for either low («LBF») or high («HBF») frequency of stolon branching were compared in two controlled-environment experiments. Selections from within both a small-leaved («Grasslands Tahora») and a large-leaved («Grasslands Kopu») clover cultivar were compared, and plants were grown under a relatively lenient defoliation treatment (expt 1) or under three levels of defoliation severity (expt 2). Carbon allocation patterns were measured by 14 CO 2 pulse-chase labelling using fully unfolded leaves on the main (parent) stolon

Managing soil acidity: old solutions can cause new problems

Acid and moderately acid soils (pH 5-6) are widespread in the farmed areas of New Zealand. Application of limestone to raise soil pH has been a common practice and re-acidification of soils requires that this be done regularly. The impact of liming and re-acidification cycles on soil chemistry is discussed and examples presented using a Southland soil: Waimumu silt loam. Wide ratios of Ca:Mg develop in the soil and further lime application is shown to damage growth of white clover but not Grasslands Tama ryegrass. Differences in surface chemistry of roots of legumes and grasses are discussed and the implications of the interactions between changes in soil chemistry and plant roots considered. Keywords acidification, calcium, magnesium, cation ratio, root CEC

Winter temperatures and reproductive development affect the productivity and growth components of white clover and phalaris growing in a mixed pasture

The effects of low winter temperatures (means down to 5�C, daily air minimums to 3�C and 82 potential frost days), frost damage and reproductive development on productivity and growth components of white clover ( Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) growing together in a mixed pasture were studied during winter and spring. Initially there was a higher proportion of white clover in the pasture which was maintained throughout winter and early spring. Leaf appearance rates were similar for both species, but petiole extension rates of white clover were significantly less than leaf extension rates of phalaris. Growth rates were higher per tiller for phalaris than per stolon for white clover. Larger sward yields of white clover were only maintained because of the higher density of white clover growing points. The lower extension rates of white clover were due to a different temperature response curve to phalaris. Below 10�C there was little growth of white clover leaves whereas phalaris had some leaf growth down to below 5�C. There was evidence that leaf extension rates of both white clover and phalaris were stimulated by reproductive development. This had a larger effect on phalaris, but also resulted in greater susceptibility to frost damage, though the damage to phalaris was not enough to reduce leaf growth to the same level as white clover. Leaf damage from frost/low temperatures was generally marginal.

Water stress affects the productivity, growth components, competitiveness and water relations of phalaris and white clover growing in a mixed pasture

The effect of water stress during summer and recovery after rain on herbage accumulation, leaf growth components, stomatal conductance and leaf water relations of white clover (Trifolium repens cv. Haifa) and phalaris (Phalaris aquatica cv. Australian Commercial) was studied in an established mixed pasture under dryland (dry) or irrigated (wet) conditions. Soil water deficits under dry conditions reached 150 mm and soil water potentials in the top 20 cm declined to nearly -2 MPa after 50 days of dry weather. Water stress severely restricted growth of both species but then after rain fell, white clover growth rates exceeded those of phalaris. Under irrigation, white clover produced twice the herbage mass of phalaris but under dry conditions herbage production was similar from both species. Leaf appearance rates per tiller or stolon were slightly higher for white clover than phalaris but were reduced by 20% under water stress in both species. Leaf or petiole extension rates were more sensitive to water stress than leaf appearance rates and declined by 75% in phalaris and 90% in white clover. The ratio of leaf or petiole extension rates on dry/wet treatments was similar for both species in relation to leaf relative water contents, but in relation to leaf water potentials phalaris maintained higher leaf growth rates. Phalaris maintained a higher leaf relative water content in relation to leaf water potentials than did white clover and also maintained higher leaf water potentials in relation to the soil water potential in the top 20 cm. Stomata1 conductances for both species declined by 80-90% with increasing water stress, and both species showed similar stomatal responses to bulk leaf water potentials and leaf relative water contents. It is suggested that the poorer performance of white clover under water stress may be due principally to a shallower root system than phalaris and not due to any underlying major physiological differences. The white clover cultivar used in this study came from the mediterranean region and showed some different responses to water stress than previously published evidence on white clover. This suggests genetic variation in responses to water stress may exist within white clover. To maintain white clover in a pasture under dry conditions it is suggested that grazing practices aim to retain a high proportion of growing points.

Influence of boron on the reproductive growth of white clover (Trifolium repens L.) cultivars

SummaryThe effect of boron on the reproductive growth of four contrasting white clover cultivars was examined in a controlled environment and glasshouse experiment. Plants grown under a nutrient regime excluding boron and those receiving 0.5 mg/litre boron had fewer stolons, reproductive stolons and inflorescences than those receiving 1, 2 or 3 mg/litre. Inflorescences were also smaller and had fewer seeds per floret. A boron concentration of 1 mg/litre gave optimum reproductive growth, higher levels of boron giving no further increase. Peduncle length and nectar quantity, but not nectar quality, were also influenced by boron indicating a possible beneficial effect of this element on pollinator activity.Cultivars differed in both vegetative and reproductive growth. Cv. Gwenda, a small leaved cultivar, had more stolons but fewer inflorescences than cv. Menna and smaller inflorescences than cv. Olwen, a large leaved cultivar. Generally, these cultivars responded similarly to boron.The implications of these results for the reproductive growth of white clover are discussed.

White Clover Yield and Persistence As Influenced by Cypermethrin, Benomyl, and Root‐Knot Nematode

White clover (Trifolium repens L.) stands commonly decline within 2 to 3 yr after establishment, due to insects, fungi, nematodes, viruses, and other factors. This study determined the effect of application of insecticide and fungicide, and infestation of southern root‐knot nematode, Meloidogyne incognita (Kofoid & White) Chitwood, alone and in all combinations, on white clover persistence, yield, and crude protein (CP) concentration. The insecticide was cypermethrin [(±)‐α‐cyano‐3‐phenoxy benzyl (±)‐cis,trans‐ 3‐(2,2‐ dichlorovinyl)‐2,2‐dimethylcyclopropanecarboxylate] and the fungicide was benomyl [methyl l‐(butylcarbamoyl)‐2‐benzimidazole‐carbamate]. ‘Regal’ white clover was grown on a Marietta fine sandy loam (fine‐loamy, siliceous, thermic Fluvaquentic Eutrochrept) for 3 yr after establishment in 1986. No effects of the treatments on yield, stand, or CP were observed in 1987. In 1988 and 1989, yields were 52 to 85% greater in cypermethrin‐treated plots, 12% greater (1988 only) in benomyl‐treated plots, and 6 to 17% lower in M. incognita‐infested plots compared with untreated plots. The number of stolons per meter was 27 to 39% greater in cypermethrin‐treated plots, 20% greater (1988 only) in benomyl‐treated plots, and 12 to 20% lower in M. incognita‐infested plots, compared with untreated plots. All treatments had little effect on CP concentration. Fewer Sitona hispidulus Fab‐larvae were found in the cypermethrin‐treated than untreated plots in 1989. White clover decline in the field was not due to any synergistic interactions between the factors evaluated in this study. When stresses such as insect, fungi, nematode, or virus are present and limit white clover growth, selection for resistance to these stresses should contribute to improved stand longevity and production of white clover.

Stimulation of vesicular‐arbuscular mycorrhiza formation and growth of white clover by flavonoid compounds

summaryThe effects of flavonoid compounds on VA mycorrhiza root colonization and growth of white clover (Trifolium repens L.) plants under growth chamber conditions are reported. The isoflavonoids, formononetin and biochanin A, previously identified from clover roots, stimulated colonization and growth of clover, while several other flavonoid compounds were inactive when tested at concentrations of 5 mg 1−1. The flavone, chrysin, when applied at concentrations higher than those tested for formononetin and biochanin A, also increased root colonization and plant growth. The stimulatory effects of the isoflavonoids on plant growth were mediated by VA mycorrhizal fungi and were dependent on concentration, period of growth and soil spore density. Maximum responses were found when 5 mg 1−1 solutions were applied to soil containing 2 to 4 VA mycorrhiza spores g−1 of soil. These results may provide insights on the molecular mechanisms of host‐fungus interaction and for the development of technology to exploit the potential of the indigenous VA mycorrhizal fungi in field soil.

Nodal structure and branching ofTrifolium repensin pastures under intensive grazing by sheep

SUMMARYThe nodal structure of white clover plants was studied in New Zealand in pastures stocked at 22·5 ewes plus lambs/ha and either continuously or rotationally grazed. Intact plants were sampled every month for a year (1988/89) by removing turves and washing out the plants. Plants were classified according to the degree of branching as first (unbranched, single-stolon plants), second, third or fourth order (plants with at least one quaternary branch). Where possible from each turf, four plants of each of the four branching orders were sampled and, for each stolon of each plant, nodes were ascribed positions numbered from the stolon apex, and the position of nodes with a live branch and the total number of nodes/stolon were recorded.The mean number (and 5 and 95% quantiles) of nodes/plant was 15·7±0·26 (9, 24) for the firstorder, 42·2±0·90 (18, 81) for the second-, 91–4±2–13 (37, 163) for the third- and 163·7±7·49 (63, 367) for the fourth-order plants. Grazing management and month of sampling had minor effects on these values. The mean number of nodes/stolon within branched plants depended on the category of the stolon within a plant, the presence or absence of an apex and on the branching order of the plant. The first 10,.15, 20 and 25 node positions accounted for, respectively, 64, 79, 90 and 95% of total nodes in the field population and 39, 62, 79 and 90% of all branches. Successful branch initiation occurred at recently formed nodes at positions 3–10, emphasizing the significant contribution of such nodes in growth and persistence of white clover in grazed swards.Where grazing management allows little consumption of stolon and there is adequate moisture, growth and fragmentation maintain the mean node composition of the branching orders reasonably constant throughout the year. Thus, any seasonal variation in the overall mean number of nodes/plant in a population must be driven by seasonal changes in the distribution of plants among the branching orders. However, there was evidence of mean number of nodes/plant decreasing in the third and fourth orders after dry conditions.

Influence of herbicides on growth and nodulation of white clover, Trifolium repens

Five herbicides commonly used for suppression of weed growth in white clover seed crops were tested for toxicity to white clover ( Trifolium repens), the nodule-forming bacteria Rhizobium trifolii, and the nitrogen-fixing symbiosis of these organisms. Trials were carried out under bacteriologically-controlled and glasshouse conditions. Overall, paraquat was more toxic to R. trifolii growth than MCPB, followed by bentazone, fusilade and kerb as the least toxic. Bentazone showed the least toxicity to plant growth, nodulation and N 2 fixation under bacteriologically-controlled conditions. All the other herbicides inhibited C 2H 2 reduction, while nodule number and plant fresh weight were lowered by paraquat. MCPB and kerb. However, when plants grown in soil were treated, kerb showed the least toxicity with fusilade, bentazone and MCPB being intermediate in toxicity. This study also showed that changes in growth medium, nitrogen status and soil moisture content can alter the activity of particular herbicides. Possible toxicity of herbicides to plant growth and N 2 fixation should be considered when using herbicides to control weeds in leguminous crops.

Lime-phosphorus interactions in the growth of temperate pasture species on highly-weathered soils

Lime and phosphorus (P) requirements for the growth of temperate pasture species on acid, well-drained soils in the Natal Midlands were evaluated in factorial field trials. Species studied were white clover (Trifolium repens), tall fescue (Festuca arundinacea) and Italian ryegrass (Lolium multiflorum). All three species exhibited large yield responses to lime and P. In addition, evidence for both positive and negative lime-P interactions was present in dry matter production data. Positive interactions, exhibited during the establishment phase of growth of white clover and Italian ryegrass, appeared to be restricted to conditions of severe P deficiency. Yield data of all species contained evidence of negative interactions, which occurred at more favourable levels of P supply. Negative interactions reflect a decrease in response to P with increasing lime supply (to salt pH values of approximately 5.5). The latter interactions are of major importance from a practical standpoint since they imply a ‘trade-off’...

The Effect of Water Stress on the Vegetative Growth of White Clover (Trifolium repensL): Comparison of Long-term Water Deficit and a Short-term Developing Water Stress

White clover plants were subjected to either a short-term developing water stress or long-term stable levels of water deficit on 'water stress columns'. The short-term stress reduced plant water status to —2 0 MPa over 15 d. The water stress columns imposed only mild levels of water stress (a reduction of 0 35 MPa in leaf water potential for the more severe treatment) but these were maintained for several weeks. The absolute growth of plants on the control columns was maintained throughout the experimental period. Vegetative growth was measured. Stolon, petiole, and lamina growth were all reduced to some extent when plants were grown symbiotically. The two regimes gave comparable results. When nitrate was supplied there was no effect of water stress. A considerably reduced absolute growth rate did not result in a similar decrease in final organ size. Stolon growth was most reduced by water stress. Leaf death during water stress was as important as changes in growth in determining final dry matter yield. Consequently, the yield of petiole and lamina from plants grown without supplied nitrate on the water stress columns was lower than that of stolon at the end of the treatment period. The merits of the water stress column system for imposing long-term water deficit are discussed.

Effects of spring defoliation and fertilizer nitrogen on the growth of white clover in ryegrass/clover swards

AbstractAn examination was made of the effects of different spring treatments on the growth of white clover in a ryegrass/white clover sward. Plots were either cut once (in February, March or April) or twice (in February and April) or left uncut. Nitrogen was applied to half of the plots in each instance. The clover was sampled at intervals of approximately 3 weeks from February to June to determine numbers of leaves and growing points and weights of plant parts. Rates of leaf appearance were also observed and estimates were made of total herbage mass from ground‐level cuts.Percentages of white clover in the herbage were higher in unfertilized than in fertilized plots and in defoliated than in undefoliated plots. The percentage increases that followed defoliation were usually maintained into later regrowth, showing that clover content was not automatically reduced as herbage mass increased. Increases in growing points were recorded after the beginning of April in defoliated unfertilized plots but not in undefoliated fertilized plots or in plots fertilized and defoliated twice during the spring period, in which numbers fell substantially.Inverse relationships were found between rates of leaf appearance, or the number of green leaves retained per stolon, and herbage mass, whereas heights of clover and grass leaves and the percentage of dry matter allocated to petiole rather than leaf in the clover increased with increasing herbage mass.We suggest that the observed differences between spring treatments in clover percentage result primarily from their differential effects on the formation and death of tillers and growing points in the early stages of regrowth.

Slot‐seeding investigations 7. The effects of two grasssuppressants on the growth of white clover introduced into permanent pasture

AbstractThe benefits of reducing competition from the surrounding grass sward against slot‐seeded clover were measured in terms of white clover dry matter production following applications of two grass‐suppressing herbicides, propyzamide and carbetamide.Clover was slot‐seeded in early June 1983 and herbicides were applied in September and October 1983. The later application was more damaging to the surrounding sward. Generally, the September spraying was more effective in encouraging white clover, especially from July of the following year. Only by September 1984 did the October applications result in higher clover yields than the September applications.Propyzamide had the greater stimulatory effect on white clover production but it also damaged the grass more than carbetamide. Increasing the dose of each herbicide increased grass damage. However, with treatments applied in September, the loss was more than compensated for by an increase in clover and in total dry matter production at the end of the year.The results suggest that either of these herbicides, but especially propyzamide, can be used to increase both total dry matter production from the sward and the contribution from slot‐seeded white clover.

Frequency distribution of shoot weight of plants in populations ofTrifolium repenspersisting by clonal growth in grazed pastures

SUMMARYOver two years (1984/85 and 1986/87), monthly sampling of shoots of white clover plants compared the populations of white clover in mixed swards at Palmerston North, New Zealand, under set stocking, rotational grazing and a combination of both systems, at a common stocking rate of 22·5 ewe equivalents/ha.The frequency distributions of shoot (or stolon) dry weight per plant in each population over the study period was described by a log-normal model, which indicated that the populations consisted of many small individuals and few large individuals. Such inequality of shoot dry weight within populations is commonly termed size hierarchy; a statistic giving a measure of such size hierarchy is the Gini coefficient. The populations under different managements had similar Gini coefficients which differed little among seasons or between years. Lack of significant correlation between the Gini coefficient and mean shoot dry weight per plant of each population indicated that, in these white clover populations, size hierarchy was independent of mean plant size.These results were considered in relation to the clonal growth of white clover in grazed swards and it is suggested that the variable nature of death of older basal stolons makes an important contribution to the variability in size of individual plants and hence to size hierarchy. As size hierarchy, as assessed by Gini coefficients, was relatively stable in these populations over 3½ years, it appears that clonal growth of white clover incorporates sufficient variability within the growth and death processes at the individual plant level to maintain the size hierarchy, irrespective of variations in mean plant size of populations.