Growth Of White Clover Research Articles

Leaf senescence and clonal growth of white clover

Leaf senescence is a programmed event where resources are mobilised from older tissues to the meristematic regions of the plant. In white clover (Trifolium repens L.), leaf and stolon senescence have an important impact on the persistence of the legume in pasture. As part of our investigation of leaf senescence, we have evidence for a central role for the plant hormone ethylene and have identified genes encoding ethylene biosynthetic enzymes. In this paper we include data showing some physiological changes as leaf tissue undergoes senescence and present evidence for the role of ethylene in regulating this process. Keywords: chlorophyll, ethylene, senescence, stolon, leaf, Trifolium repens L.

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.

Sewage Sludge and Heavy Metal Effects on Nodulation and Nitrogen Fixation of Legumes

AbstractEffects of sludge‐borne heavy metals on plant growth, nodulation, and nitrogen (N2) fixation of alfalfa (Medicago sativa L.), white clover (Trifolium repens L.), and red clover (Trifolium pratense L.) were examined. Plants were grown in the greenhouse in pots containing soil (Typic Paleudults) obtained from plots where heat‐treated and Nu‐Earth sludges were applied in 1976 and 1978, respectively. Two soil pH regimes (low and high) were examined for each of the treatments. Nitrogen fertilizer (NH4NO3) was applied to one‐half the pots and each legume was inoculated with the appropriate Rhizobium culture. Soil pH and sludge type significantly affected uptake of metals with phytotoxicity observed in the Nu‐Earth, low pH soil. Nodulation was reduced, but not always completely eliminated in all low pH treatments, including the controls. Symbioses were generally ineffective in low pH treatments. In soils where pH was above 6.0, there was a significant increase in shoot weight and total shoot N with sludge addition. Plants derived significant quantities of N from soil, where sludge was applied many years ago. When pH was maintained at 6.0 or higher the results show that heavy metals in soil, and the resulting concentration in plants, had no effect on any of the parameters examined.

Effect of VA mycorrhizas on phosphorus uptake and growth of white clover (Trifolium repensL.) growing in association with ryegrass (Lolium perenneL)

Abstract In a phosphorus‐deficient soil, vesicular‐arbuscular mycorrhizas (VAM) helped white clover to compete more effectively with ryegrass for phosphate, resulting in better phosphate acquisition by mycorrhizal clover than non‐mycorrhizal clover. The benefit was greatest when competition from ryegrass was severe. Mycorrhizal clover did not grow much faster than non‐mycorrhizal clover, probably because of competition for light from neighbouring ryegrasses. When the soil was fertilised with phosphate, clover and ryegrass yields increased, and non‐mycorrhizal clover plants outyielded mycorrhizal plants. Similar parasitic effects of VAM have been recorded before. It is concluded that the presence of VAM linkages between clover and grass roots will probably negate any benefits to clover of the introduction of elite VAM fungi to pasture soils. Genetic manipulation of a host plant's response to VAM, may be a more profitable way of improving the phosphate nutrition of white clover in mixed swards.

Seedling White Clover Response to Defoliation

Defoliation during the early stages of seedling development can influence growth of white clover (Trifolium repens L.). Our objective was to determine the response of cultivars with diverse leaf sizes to defoliation across a range of seedling growth stages. ‘Regal’ (large‐leaf), ‘Louisiana S‐1’ (medium‐large‐leaf), ‘Grasslands Huia’ (medium‐smallleaf), and ‘Aberystwyth S184’ (small‐leaf) were grown in the greenhouse and were initially clipped to remove all leaf (except cotyledons) and petiole tissue (1.0‐cm stubble) when seedlings attained a unifoliolate leaf or one, two, four, and eight trifoliolate leaves. Seedlings were subsequently clipped in the same manner every 7 or 28 d for the next 28 d. Plant response to defoliation was assessed 7, 14, 21, and 28 d after the last clipping. Seedling shoot dry weight of all cultivars increased linearly in response to initial leaf stage when subsequent clipping occurred every 7 d after the initial defoliation. When subsequent clipping was delayed 28 d, defoliation after the four‐trifoliolate stage did not influence shoot weight of any cultivar except Regal. Despite fewer numbers of leaves after regrowth, seedling leaf area of Regal was always greater than that of the other cultivars. Number of stolon branches of Regal and Louisiana S‐1 increased in response to leaf stage at initial defoliation (0.15 branches stage−1), while that of Grasslands Huia and Aberystwyth S184 was relatively unchanged after the four‐ to six‐trifoliolate stage. Permitting white clover seedlings to attain advanced leaf stages before initial defoliation and increasing the time interval before subsequent defoliation will enhance seedling growth and potential survival.

White Clover Growth and Morphology under Contrasting Cutting Regimes

Climatic conditions contribute to reduced white clover (Trifolium repens L.) productivity and plant survival in the southeastern USA, particularly during the summer. Our objective was to determine the influence of cutting height and frequency on yield and plant morphological traits associated with survival of white clover under humid‐subtropic conditions. Regal (large‐leaf), Louisiana S‐1 (medium‐largeleaf),and Grasslands Huia (medium‐small‐leaf) white clover were sown on a Catalpa silty clay (fine, montmorillonitic, thermic Fluvaquentic Hapludoll) and were cut every 7, 28, and 49 d at a 2.5‐ and 10‐cm stubble height from March to November. Forage yield was measured at each harvest. Stolon growth and branching (growing point density; GPD) and post‐harvest leaf area index (LAD were measured in May, August, and November. Dry matter (DM) yield measured by season (spring, summer, and autumn) increased as leaf size increased and cutting height decreased. The effect of cutting height on stolon DM was opposite that of its effect on DM yield. After the spring, stolon DM of all cultivars was reduced by harvesting at 2.5‐ vs. 10.0‐cm stubble, regardless of cutting interval. Within a cutting height, increasing the harvest interval from 7 or 28 to 49 d generally resulted in greater stolon DM accumulation by autumn. During much of the growing season, there was a positive association between stolon GPD and post‐harvest LAI. Our results suggest that close defoliation of white clover (2.5‐cm stubble) during the summer and autumn detrimental to plant survival, particularly when combined with a short (7‐d) defoliation interval.

Effect of interval between harvests and spring‐applied fertilizer N on the growth of white clover in a mixed sward

AbstractA perennial ryegrass (Lolium perenne)‐white clover (Trifollum repens) sward, that had been grazed for over 2 years, was cut at 1‐, 2‐, 3‐ or 6‐week intervals from 18 April to 28 November 1986. The effects of two rates of N application in spring, 0 and 66kg Nha−1, were compared. Clover growth was studied in three six‐week periods that began on 18 April, 18 July and 17 October respectively. Increasing the interval between cuts increased the yield of herbage without reducing the proportion of clover in the harvested herbage, but the combination of applied N and the six‐week interval was harmful to clover production. Increasing the interval between cuts tended to increase the proportion of resources allocated to stolons rather than to leaves, and to increase the weight of new dry matter (DM) per growing point rather than per m2. In the third period of the study, when the ten youngest internodes per stolon were examined separately, all ten ages of internode were found to have been affected by the cutting management. This was indicated by the positive effect of the length of the interval between cuts on the weights of N, P and K per intemode. The concentrations of N, P and K were highest in the youngest intemodes. The application of N reduced the proportion of new DM allocated to stolen rather than to leaf and it reduced the number of clover growing points per m2.

Influence of seed quality on seedling growth of white clover (Trifolium repens L.)

AbstractThe influence of seed quality on seedling growth of white clover cv Makibashiro plants was examined in a controlled environment. The average dry matter (DM) yield of 70‐day‐old seedlings from a poor‐quality seed lot was significantly less than that from a high‐quality seed lot. In both seed lots, a linear relationship between the DM yield and time from sowing was observed. The slope of regression of DM yield against time from sowing for the poor‐quality seed lot was less than the equivalent slope of the high‐quality seed lot, suggesting that possible avenues for increased DM accumulation in a high‐quality seed lot are somewhat indirect (time of emergence, uniform emergence etc.); a direct effect of seed quality on the photosynthetic ability of plant tissue seems less likely to occur. The root: shoot ratios declined in both groups of plants with increasing age. Seedlings from the high‐quality seed lot reached a stable root:shoot ratio (equilibrium state) much earlier than those from the poor quality seed lot. The seed quality had no influence on the proportion of DM partitioned to various organs. The results of this study are discussed in relation to field establishment.

Effect of vesicular-arbuscular mycorrhizal and phosphatase-producing fungal inoculation on growth and nutrition of white clover supplied with organic phosphorus

In a pot experiment white clover was grown for 50 d in two sterilized low phosphorus soils supplied with organic phosphorus as sodium phytate. Seed inoculation withAspergillus fumigatus, a phosphatase-producing fungus (PPF), and soil inoculation withGlomus mossece, a vesicular-arbuscular mycorrhizal (VAM) fungus resulted in increased shoot and root dry mass and root length, phosphatase activity in soil and shoot concentrations of P and to a lesser extent of Mg. The effects on these parameters were most distinct upon combined inoculation treatment (PPF+VAM). A significant increase in hyphal length density and decrease in Mn concentration was observed only upon PPF+VAM treatment. Shoot concentrations of Cu and Zn were highly enhanced by VAM but not by PPF. Of the total P uptake the PPF contribution accounted for 39–41 %, VAM contributed 41–50 % and their combination resulted in 55–58 %, in comparison to only 38–40 % contribution due to soil microorganisms under unsterilized conditions. The depletion of organic phosphorus in the rhizosphere soil increased in the order (PPF+VAM)>VAM>PPF> unsterilized soil>sterilized soil. The results demonstrate the efficient use of phytate phosphorus byA. fumigatus andG. mosseœ and suggest that dual inoculation is superior to a single one.

Effect of Arbuscular Mycorrhizal Inoculation and Phosphate Application on Phosphorus Uptake and Growth of White Clover (Trifolium repens L.) and Onion (Allium cepa L.) in Andosols

Effect of Arbuscular Mycorrhizal Inoculation and Phosphate Application on Phosphorus Uptake and Growth of White Clover (Trifolium repens L.) and Onion (Allium cepa L.) in Andosols

Effects of plant-parasitic nematodes and rhizosphere microorganisms on the growth of white clover ( Trifolium repens L.) and perennial ryegrass ( Lolium perenne L.)

A pot trial was carried out to study the effects of plant-parasitic nematodes and rhizosphere microorganisms on the growth of perennial ryegrass ( Lolium perenne) and white clover ( Trifolium repens). Plants were grown together in Horotiu sandy loam (Vitric Hapludand). The treatments consisted of: untreated field soil (UT); soil frozen to −20°C to reduce nematodes (FR); soil fumigated with chloroform to kill most soil organisms (FU); and fumigated soil inoculated with a layer of frozen soil to reintroduce organisms present in frozen soil (FUI). The mean wet weights of white clover and ryegrass grown in UT soil for 6–9 weeks were only 10 and 60%, respectively, of those grown in FR soil and 5.8 and 56%, respectively, of those grown in FU soil. The severe growth reduction of white clover in UT was attributed to early invasion of roots by two nematode species, Heterodera trifolii and Meloidogyne hapla, which were detected in stunted 7-day-old seedlings. In the FR and FUI treatments, the freeze-thaw process appeared to have killed the second stage juveniles but not the eggs, which hatched to release more juveniles to invade white clover roots. Plant growth in FR, and to a lesser extent in FUI treatments, was reduced in comparison with FU, where there was no nematode invasion. The bacterial numbers in surface-sterilized roots were unaffected by any of the treatments. This suggests that the entry of bacteria into root tissues is independent of the wounding caused by nematodes. The mean bacterial numbers of the medians (means of log cfus across treatments and plant species of the median numbers across replicates) for “total” bacteria, fluorescent pseudomonads, Gram-negative bacteria and Gram-positive bacteria from surface-sterilized roots were 4.26, < 2, 2.94 and 3.08 for the four treatments, respectively. The most common bacterial genera identified were Pseudomonas and Bacillus. Fungi isolated from surface-sterilized roots included Fusarium oxysporum, Codinaea fertilis and many sterile fungi, with F. oxysporum being the most common identified fungus in FU and FUI treatments. C. fertilis was killed by the soil freezing process. F. oxysporum did not appear to be associated with a decrease in dry matter production of either white clover or ryegrass, but C. fertilis may have adversely affected the ryegrass dry matter production in the treatment UT.

Effects of Mowing Regimes on the Growth and Vegetation Dynamics of Established White Clover (Trifolium repens L.) Cover for Weed Suppression.

To determine the optimal mowing regime for the maintenance of two cultivars (Grasslands Huia and California Ladino) of white clover sod and its weed suppression, field trials were conducted for two years beginning in 1991. Sixteen mowing regimes were evaluated: all combinations of frequency and time of mowing 4 times a year, spring (mid April or early May), June, August and October. During the first year, mowing regimes little affected clover growth and the vegetation dynamics, but in the second year they significantly affected them. Clover coverage declined in the summer of 1993 because of the depression of clover growth and weed invasion caused by creation of a gap after mowing. June mowing, in particular, induced emergence of large summer grasses, e. g., Setaria faberi and Digitaria ciliaris, which suppressed clover. Mowing in August and October increased emergence of winter annuals, while June mowing increased that of summer annual weeds. The winter annuals were not noxious, but some summer grasses had adverse effects on clover. Regardless of mowing, Rumex spp. and Lolium multiflorum increased their dominance ratio in all the treatments. ‘Ladino’ exhibited more continuous dense cover and superior weed suppression than ‘Common’. Mowing at other than ‘spring flush’ stage should be avoided to maintain established clover sod.

White clover growth and morphology in dairy pasture in the Waikato region of northern New Zealand

Abstract Seasonal changes in clover plant growth and structure in a Waikato dairy pasture were monitored over 1 year. Pasture plugs and clover plants separated from turves were removed from paddocks before grazing. They provided data on clover plant density, total stolon biomass, vertical distribution of stolons in the sward, and various morphological characteristics. Plant density averaged 610 plants/m2 which was higher than that recorded in a comparable study of Manawatu sheep‐grazed pastures. Stolon biomass was also greater in the dairy pasture; most of this stolon was on the soil surface (58%) whereas in sheep‐grazed pastures most was buried. The proportion of stolon within each class varied throughout the year. Clover plants fragmented during spring as was shown for Manawatu sheep pastures. Plant density therefore peaked during spring while values for plant morphological characteristics were low since most of the clover population comprised small, 1st‐order plants. Overall, clover plants in Waikato dairy pastures were larger than those in Manawatu sheep‐grazed swards. These differences probably resulted from interactions between several factors including cultivar, climate, soil type, companion species, farm management, and grazing effects.

Leaf, stolon and root growth of white clover (Trifolium repens L.) in response to irrigation with saline water

The effect of irrigation with water at salinity concentrations of 2.6 and 5.2 dS m−1 on the growth of pure swards of six cultivars of white clover (Trifolium repens L.) was examined over three irrigation seasons at Tatura, Victoria, Australia. After two irrigation seasons, soil EC e levels increased to 6 dS m−1 at 0–60 cm depth in the higher salinity treatment resulting in highly significant (p < 0.001) reductions in shoot dry matter production, flowering densities and petiole and stolon densities. These saline conditions also increased (p <0.001) concentrations of Cl and Na in the shoots and reduced (p < 0.001) leaf water potentials and canopy photosynthetic efficiency rates especially at high temperatures. In contrast, root growth increased at shallow depths (0–15 cm) under both saline irrigation treatments (p <0.001). Cultivars differed significantly in salt tolerance (p < 0.001), with cultivars Haifa and Irrigation exhibiting superior tolerance in terms of lower reductions in herbage yield (p <0.05) and petiole densities (p <0.001) during one irrigation season and lower concentrations of Na and Cl in the shoots (p <0.05) compared with the other four cultivars (Aran, Kopu, Pitau and Tamar). In addition, canopy photosynthetic efficiency rates (A *) in plots irrigated with water at 5.2 dS m−1 were higher in cultivar Haifa compared with cultivar Tamar (p <0.05). The salt tolerance ranking obtained for the six cultivars was in broad agreement with earlier greenhouse studies. Consequently, it appears that, while white clover is an extremely salt-sensitive species, it is possible to grow cultivars which display greater salt tolerance than other cultivars and which provide some scope to increase, or at least to maintain, pasture yields in areas where the soil salinity is low to moderate or where pumped saline groundwater is re-used for Irrigation.

Effect of light quality (red: far-red ratio) and defoliation treatments applied at a single phytomer on axillary bud outgrowth in Trifolium repens L.

We studied the effects of light quality and defoliation on the rate of phytomer appearance and axillary bud outgrowth in white clover. The treatments were applied to one phytomer, a phytomer being defined as the structural unit comprising a node, internode, axillary bud, subtending leaf and two nodal root primordia. Light of a low red:far-red (R:FR) ratio (0.27) was applied to a "target" phytomer either (i) within the apical bud and then to the axillary bud after emergence of the phytomer from the apical bud, or (ii) to the axillary bud only after emergence. The light conditions were directed to these specific parts of the plant by collimating light from small FR light-emitting diodes; with this technique we were able to change the light quality without any change in the level of photosynthetically active radiation. The subtending leaf of the target phytomer was retained or defoliated when it had emerged from the apical bud. FR light applied from the time the phytomer was within the apical bud caused a delay in branch appearance at the target phytomer. In contrast, direct treatment of the axillary bud with FR light after it had emerged from the apical bud did not result in any delay in branch appearance. As the light treatment of the apical bud may have changed the light environment of any of the organs contained in the bud we were unable to ascribe the delay in branch appearance to light perception by any particular organ. However, indirect evidence leads to the conclusion that the likely site of light perception was the developing leaf subtending the axillary bud while it was the outermost phytomer within the apical bud. These results do not support the hypothesis that the R:FR ratio of light incident at an axillary bud site is the environmental factor that controls bud development. Defoliation of the unfolding leaf reduced the rate of phytomer appearance on the main stolon but had no immediate effect on branch appearance. As a consequence there was a reduction in the number of phytomers between the stolon apical meristem and the first phytomer with a branch. This is frequently taken to indicate a relaxation of apical dominance, but in this case was found not to involve a direct effect on bud activity. A current model of white clover growth suggests that there is integration of activity between apical meristems but independence of activity and response to the local micro-environment by axillary buds. In contrast, we found that (i) defoliation reduced phytomer appearance only at the main stolon apical meristem and not at all the meristems in the plant and (ii) that a change in the local light environment of an axillary bud had no discernible effect on bud activity once the bud had emerged from the apical bud but could delay branching if applied before emergence. These results are at variance with the predictions of the model.

Evaluation of seven Italian and hybrid ryegrasses under sheep grazing in Southland, New Zealand

Abstract Three Italian and four hybrid ryegrass cultivars (Lolium multiflorum and L. boucheanum Syn. L. hybridum) sown with the white clover cultivar Grasslands Huia (Trifolium repens), were evaluated under frequent/hard grazing or infrequent/ lax grazing. Dry matter (DM) yields and species composition were assessed for 5½ years. Ryegrass tiller and white clover growing point population densities were determined annually, and leafrstem ratios every spring and autumn. Ryegrass tillers were assessed for infection with an Acremonium‐like endophytic fungus and bacterial wilt disease (Xanthomonas campestris pv. graminis). The Italian ryegrass cultivars Moata and Concord had total yields 33% greater than the mean of the other cultivars (1800 kg DM/ha) over the first autumn and winter. The Italian cultivars persisted well for 3 years, except Concord which had a high incidence (34%) of bacterial wilt. Of the hybrid ryegrasses, cultivar Corvette had high ryegrass yields in the first year (9800 kg DM/ha), similar to those of the Italian cultivars, and continued to be high‐yielding and persistent throughout the experiment. However, its degree of aftermath heading was high and probably reduced ryegrass herbage quality in summer and autumn. An inverse relationship between ryegrass yield and white clover yield resulted in few significant differences in total yields between cultivars. Infrequent/lax grazing maximised total annual yields (+5%) but decreased white clover yields (‐13%). With the importance placed on achieving high white clover growth in the cool temperate environment of Southland, choice of ryegrass cultivar should consider factors such as pasture quality (primarily percentage composition of white clover), tolerance of the cultivar to a range of grazing managements, and seasonal herbage production. The presence or absence of endophyte was not considered a major factor influencing the long‐term persistence or productivity of the cultivars evaluated at this site.

Cell Wall Composition of Diverse Clovers during Primary Spring Growth

Forage digestibility is influenced by plant cell wall composition. We compared changes in cell wall composition of the herbage and plant fractions of four clovers differing in life cycle and growth habit and examined the relationship between digestibility and cell wall composition in these plant fractions. Primary spring growth of berseem (Trifolium alexandrinum L.), red (T. pratense L.), subterranean (T. subterraneum L.), and white (T. repens L.) clover was harvested in each of 2 yr beginning in late March and thereafter every 10 d (eight harvests total). Cell wall, hemicellulose, cellulose, and lignin concentration were determined for leaf, petiole, stem, and reproductive fractions and herbage at each harvest. Herbage cell wall concentration of berseem, red, and white clover increased 3.1, 2.4, and 0.8 g kg−1 d−1, respectively. Maximum herbage cell wall concentrations of annual berseem and subterranean clover herbage were greater than those of perennial red and white clover(500 and 497 vs. 425 and 280g kg−1 respectively). With the exception of subterranean clover, leaf cell wall concentration of all clovers ranged from ≈ 200 to 300g kg−1 Trends for stem cell wall and hemicellulose Concentration of erect‐growing berseem and red clover were similar, while petiole cell wall and hemicellulose trends were similar for annual berseem and subterranean clover. Herbage and plant fraction cell wall concentration were negatively correlated with digestibility due primarily to the inverse relationship between digestibility and cell wall‐ligning cncentration. The minor differences in leaf cell wall concentration during primary spring growth indicate minimal differences exist among these clovers in relation to their value to grazing ruminants.

The influence of the radiation environment around the node on morphogenesis and growth of white clover (Trifolium repens)

AbstractThe growth of clonally propagated clover plants (Trifolium repens) in the glasshouse was compared with their growth under canopies of Tropaeolum peregonium with or without supplementation from red light emitting diodes (LEDs) directed at the youngest node bearing a fully expanded leaf. The T. peregonium was grown over a net support so that its roots did not meet those of the clover. A similar experiment was set up in a permanent grassland using canopy shade from various grass species (Holcus lanatus, Lolium perenne and Agrostis stolonifera) with and without supplementation. The LEDs increased the ratio of red to far red radiation (R/FR) received by the treated node with no apparent increase in photosynthetically active radiation (PAR) during the day.The morphogenetic effects of canopy shading (notably fewer branched nodes and less well‐developed branches) were largely removed by supplementation so that the supplemented plants came to resemble those grown in full daylight, particularly in the glasshouse experiments. The results highlight the Importance of the radiation environment at the base of the canopy in the morphogenetic responses of plants to putative competition, and the data are consistent with the hypothesis that responses are communicated acropetally along the stolon.

Soil nitrogen and carbon status following clover production in louisiana

Abstract Field studies were conducted for four to seven years on two soils, Tangi silt loam (Typic Fragiudalf, fine‐silty, mixed, thermic) and Dexter loam (Ultic Hapludalf, fine‐silty, mixed, thermic), to determine the effects of phosphorus (P) applications on growth and nitrogen (N) content of white clover (Trifolium repens L.) and subterranean clover (Trifolium subterranum L.) and on ammonium (NH4 +)‐ and nitrate (NO3 ‐)‐N, total N, and organic carbon (C) levels in the soils at the end of the study. Phosphorus applications consistently and significantly increased forage yields and led to significantly higher N yields by the clovers. Increases in plant yields and N2‐fixation, however, were not reflected in higher soil N and C levels. On Tangi soil, NH4 +‐ and NO3 ‐‐N levels were lowest where no P was applied but no statistically significant differences (P < 0.05) were found among P rates above 20 kg/ha. On the Dexter soils, no significant differences were found at any P application level. Significant dif...

White Clover Response to Grazing Method

AbstractGrazing management is a major factor influencing white clover (Trifolium repens L.) growth. Our objective was to determine the response of white clover cultivars differing in leaf size to grazing method (continuous vs. rotational stocking) using cattle (Bos spp.). In each of 2 yr, a predominantly tall fescue (Festuca arundinacea Schreb.) sod on a Savannah fine sandy loam (fine‐loamy siliceous, thermic Typic Fragiudult) was oversown in September with ‘Grasslands Huia’ (medium‐small leaf), ‘Louisiana S‐1’ (medium‐large leaf), and ‘Regal’ (large leaf) white clover. From March to August of the following year, plots of each cultivar were stocked continuously (3‐ to 5‐cm stubble) on rotationally (grazed to 5‐cm stubble every 35 to 38 d). Clover growth was measured prior to rotational grazing and stolon survival was determined in November. When precipitation during the grazing season was 59% above normal, grazing method had no influence on mean single leaf area, stolon dry weight, and stolon growing point density of white clover. In contrast, continuous stocking reduced these responses when precipitation was 32% below normal the following year. Cultivar ranking for mean single leaf area was generally the same as that for leaf size category: Grasslands Huia &lt; Louisiana S‐1 &lt; Regal. Although stolon length and growing point density were frequently greatest for Grasslands Huia, stolon survival of Grasslands Huia was no greater than that of the larger‐leafed cultivars. Despite varying effects of grazing method on growth and morphology, stolon survival of white clover was always greater under rotational stocking.