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1.
The number of tillers per unit area of pure swards of S23 and S24 perennial ryegrass, S37 cocksfoot, S48 timothy and of a S23 perennial ryegrass/white clover sward, were examined at intervals of 4 weeks during a period of two years. The monthly appearance of new tillers and the death of tillers of S23 and S24 ryegrass and S48 timothy were followed for 15 months. The studies were made with and without irrigation.
The number of tillers varied with season through the year. Tiller numbers increased rapidly in late winter or early spring, and then declined until midsummer. Numbers rose again between June and August. This seasonal pattern of tiller numbers was most marked in ryegrass and timothy and least in cocksfoot. The effect of irrigation on tiller numbers was variable, and usually small in relation to the overall seasonal fluctuations in tiller numbers, but dry soil conditions could delay an increase in tiller numbers between June and August. The relationship between seasonal fluctuations in tiller number and root growth of swards is discussed.  相似文献   

2.
Four varieties of perennial ryegrass are compared throughout the seeding year and the first four harvest years (1954–58). Two of the varieties, Irish 'commercial' and New Zealand, are of 'early' type; and the others, Glasnevin and S23 are, 'late'.
New Zealand gave the most grazing, 1% more than 'commercial' and Glasnevin, and 5% more than S23.
The 'early' varieties contrasted markedly with the 'lates' in seasonal growth.
In persistency and in resistance to invasion by unsown species, the 'lates' were better than the 'earlies' S23 was outstanding, and New Zealand had an advantage over 'commercial'. The 'earlies' were the more compatible with clover.
New Zealand appears to have most merit, but sowing of more than one variety may give better results.  相似文献   

3.
The effects of sowing from 10 to 50 lb/acre of tall-fescue seed on plant establishment and on the annual and seasonal distribution of DM yield of tall fescue and its companion grasses were measured through two growing seasons. Increasing the seed rate increased plant numbers per unit area and decreased per cent establishment. Adding Scots timothy as a companion grass depressed both plant number and per cent establishment. S37 cocksfoot and New Zealand perennial ryegrass reduced both still further. Total annual dry-matter production was relatively unaffected by varying either the seed rate or the companion grass. The contribution of tall fescue to total production was highest when sown alone and was successively reduced by timothy, perennial ryegrass and cocksfoot. When sown alone there were only slight differences in contribution of tall fescue due to seed rate. With any companion grass the contribution from tall fescue increased with increasing seed rate. Early growth was not reduced by modifying seed rate but was reduced by all the companion grasses. It is concluded that increasing the seed rate of tall fescue above 30 lb is not justified, that Scots timothy can be sown at 3 lb/acre with tall fescue without affecting total production or early growth of the mixture, with the advantages of control of unsown species and improved palatability of the herbage.  相似文献   

4.
Post-flowering tillering responses of 'Ellett' and 'Grasslands Ruanui' perennial ryegrass ( Lolium perenne L.) cultivars after inflorescence production were studied at INRA, Lusignan in France, at near ambient light (absence of light competition, control treatment) and under shading (low-light intensity and low red–far red ratio). A dense sward containing inflorescence bearing plants of both perennial ryegrass cultivars at ambient light was cut to a height of 50 mm above ground level after which the light treatments were imposed. Forty-five days later, data were collected on the number of tillers per plant, the number of new tillers per original tiller and the dry weight of vegetative and reproductive tillers. Regardless of light treatment, cv. 'Ellett' had fewer tillers per plant, higher weight per tiller and a higher proportion of reproductive tillers than did cv. 'Grasslands Ruanui'. Number of tillers per plant and number of new tillers per tiller were consistently reduced under shade compared with the control treatment for both cultivars. When shaded, weight of reproductive tillers of cvs 'Ellett' and 'Grasslands Ruanui' were 40% and 43%, respectively, less than the control, whereas vegetative tiller weight did not change. In addition, differences between cultivars in the tillering strategy after flowering seem to be unaffected by the light environment. Thus, field observations regarding tillering of cvs 'Ellett' and 'Grasslands Ruanui' were consistent with current results suggesting different grazing managements are needed after flowering to optimize the replacement of tillers for both cultivars.  相似文献   

5.
Poor persistence of perennial ryegrass swards is a common problem; however, there is a lack of long‐term studies to understand the mechanisms associated with poor persistence. This study describes an experiment to test the hypothesis that high ryegrass seeding rates (>18 kg seed per ha) reduce long‐term population persistence because of smaller plant size and poorer survival during the first year after sowing. Four cultivars, representing four functional types of perennial ryegrass, were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed per ha) with white clover in three regions of New Zealand. Swards were monitored for 5 years. No evidence was found to indicate a lack of persistence of ryegrass‐based swards sown at higher seeding rates. During the first year, swards sown at higher seeding rates had greater herbage accumulation (except at the Waikato site), greater ryegrass tiller density and greater ryegrass content. This initial impact of high seeding rates had largely dissipated by the fourth year, resulting in swards with similar annual herbage accumulation, tiller density and botanical composition. Similarly, there were relatively few differences among cultivars for these variables. Although high seeding rates did not negatively impact sward persistence, geographical location did, with strong evidence of ryegrass population decline at the Waikato site for all treatment combinations, some decline in Northland, and stable populations in Canterbury. It is possible that productive perennial ryegrass pastures can only be sustained for 4–5 years in some situations, even when the best ryegrass technology and management practices are used.  相似文献   

6.
A field experiment with mixed swards of perennial ryegrass and while clover carded out in 1982–83 using small cut plots is described. With perennial ryegrass, lime slightly decreased annual dry matter (DM) production in 1982 (the sowing year) but increased it in 1983 (the first harvest year) by about 1 t ha-1. Applications of N and P produced small increases in DM in 1982 and greater increases in 1983. In the latter season annual DM production varied from an average of 3·5 to about 10 t ha-1 with 0 or 480 kg N ha-1 applied in three equal-sized dressings throughout the growing season. Application of 40 kg P ha-1 in 1982 increased DM production by about 2·5 t ha-1 in 1983 but higher rates had little effect. Fifteen mg extractable P kg-1 soil seemed sufficient to support levels of production normally expected from ryegrass pastures in upland Scotland, Applications of K did not affect DM production. N increased tiller weight and sward height of ryegrass; lime and P tended to increase tiller weight but this effect was not statistically significant. Leaf appearance and tiller number were not affected by treatments.
The white clover content of the pasture was decreased 10-fold by application of N and increased by lime and P (1·45 and 1·46-fold. respectively). The DM response to P was most apparent in limed soil and was also affected by the siting of the plots in the experimental area. Effects of lime and P on growth of white clover were to increase the number of stolon growing points and root nodule numbers per unit area.
The results emphasize the importance of lime and P fertilizer for establishment and growth of pasture in this soil and the differences between white clover and ryegrass in their responses to these.  相似文献   

7.
The investigation compared the agronomic characteristics of Irish and S 23 perennial ryegrass plants grazed for 11 years with newly propagated Irish and S 23.
The sample drawn from the surviving Irish population displayed the following characters relative to the newly propagated plants: the date of ear emergence was 2 days later, the growth habit at emergence was similar, the aftermath was more leafy.
The S 23 subjected to the same management as the Irish was identical with newly propagated S 23, apart from earlier ear emergence. The possible reason for this and the consequent limitations of the results are discussed.  相似文献   

8.
After uniform defoliation in February, spaced plants of S.48 timothy were cut on one of 12 fortnightly dates, starting at the end of March.
Analysis of the herbage removed at each cut showed an increase in plant and unit tiller weight throughout the season, but a decline in the number of tillers, especially before the beginning of shooting.
The date of ear emergence was not affected by cutting up to 5 May and only slightly delayed in plants cut on 19 May. Plants treated subsequently flowered much later but after a fairly constant interval following defoliation.
Cutting on and after 7 April depressed fertile tiller formation with increasing severity, until only vegetative tillers appeared in the recovery growth following treatment at the beginning of August.
Seed yield per plant declined with the decrease in fertile tiller numbers, but after the early cuts some compensation by production of slightly more seed per ear was recorded.
The results are discussed in terms of the physiological transition of the plant towards flowering.  相似文献   

9.
The influence of defoliation on the root, stubble and herbage weights of perennial ryegrass during establishment was studied on spaced plants in the greenhouse and field.
In the greenhouse trial the rate of root elongation was reduced by a single defoliation. In both the field and greenhouse, cutting reduced the number of roots and tillers per plant but increased the number of roots per tiller. A few weeks after defoliating plants in the field there was a lower root weight on the cut plants than on the uncut. Eventually the influence of a single cut disappeared, but if the cutting was in the laie summer or autumn the plants commenced the winter with a smaller amount of root and stubble, and this appeared to have a deleterious effect on the earliest spring growth.
Herbage growth in March and April was positively correlated with both root and stubble weights in the previous November.
As the number of cuts during the establishment period (March-November) was increased from 0–4 the root and stubble weight per plant progressively decreased.
The root and stubble weights decreased during the winter.  相似文献   

10.
The change in structure of continuously grazed versus infrequently cut swards of perennial ryegrass ( Lolium perenne L), cv. S23, was investigated during their first full harvest year. Measurements were made from early May until late September. The intensity of stocking by sheep in the grazed sward was adjusted in an attempt to maintain a high level of radiation interception and the cut sward was harvested at approximately monthly intervals.
The herbage mass, lamina area index and radiation interception of the cut sward varied in a cyclic pattern between harvests but in the grazed sward these parameters showed considerably less variation, although they all increased early in the season and then declined later. The proportion of dead material above ground increased throughout the season in both sward types but was more marked in the grazed sward.
There were major differences between the grazed and cut swards in the number of tillers per unit ground area; the difference became more marked throughout the season and by September the tiller densities in the grazed and cut swards were 3·204 m-2 and 6·203 m-2 respectively. Divergence in tiller density was associated with differences in specific stem weight and leaf area per tiller.
Rates of appearance and death of leaves on tillers in the grazed sward were determined. During May, leaf appearance exceeded leaf death but this was reversed in June. During the rest of the season as a new leaf appeared on a tiller so the oldest leaf died.  相似文献   

11.
A field study was undertaken between April 2003 and May 2004 in southern Tasmania, Australia to quantify and compare changes in herbage productivity and water‐soluble carbohydrate (WSC) concentration of perennial ryegrass (Lolium perenne L.), prairie grass (Bromus willdenowii Kunth.) and cocksfoot (Dactylis glomerata L.) under a defoliation regime based on leaf regrowth stage. Defoliation interval was based on the time taken for two, three or four leaves per tiller to fully expand. Dry‐matter (DM) production and botanical composition were measured at every defoliation event; plant density, DM production per tiller, tiller numbers per plant and WSC concentration were measured bimonthly; and tiller initiation and death rates were monitored every 3 weeks. Species and defoliation interval had a significant effect (P < 0·05) on seasonal DM production. Prairie grass produced significantly more (P < 0·001) DM than cocksfoot and ryegrass (5·7 vs. 4·1 and 4·3 t DM ha?1 respectively). Plants defoliated at the two‐leaf stage of regrowth produced significantly less DM than plants defoliated at the three‐ and four‐leaf stages, irrespective of species. Defoliation interval had no effect on plant persistence of any species during the first year of establishment, as measured by plant density and tiller number. However, more frequent defoliation was detrimental to the productivity of all species, most likely because of decreased WSC reserves. Results from this study confirmed that to maximize rates of regrowth, the recommended defoliation interval for prairie grass and cocksfoot is the four‐leaf stage, and for perennial ryegrass between the two and three‐leaf stages.  相似文献   

12.
Failure of perennial ryegrass swards to persist is a key issue on dairy farms in many areas of the world. This study describes an experiment conducted to test the hypothesis that high ryegrass seeding rates (>18 kg seed ha?1) reduce plant size and physical survival during the first year after sowing, with negative implications for population persistence. Four cultivars representing four functional types of perennial ryegrass were sown at five seeding rates (equivalent to 6, 12, 18, 24 and 30 kg seed ha?1) with white clover in three dairying regions of New Zealand. Plant establishment rates, size and survival were measured for the first 13 months after sowing. Herbage accumulation, botanical composition and perennial ryegrass tiller density were also monitored. Increasing seeding rate reduced plant survival in the seven weeks after sowing, reflecting likely differences in germination and very early mortality of small seedlings. Thereafter, plant survival was relatively high and consistent across seeding rates at two sites but was consistently greater in the 6 kg ha?1 treatment compared with the 24 and 30 kg ha?1 treatments at one site. Higher seeding rates also increased ryegrass tiller density and the contribution of ryegrass towards total herbage biomass but reduced the contribution of white clover. Very few cultivar × seeding rate interactions were detected for any of the measured variables. Many of the seeding rate effects dissipated by the end of the first year after sowing, indicating that high seeding rates did not predispose swards to poor persistence in the longer term, irrespective of ryegrass functional type.  相似文献   

13.
In outbreeding species, such as perennial ryegrass, most plants are heterozygous for genes controlling agronomic characters and varieties must usually be based on more than one plant to avoid inbreeding depression. This leads to the possibility of change under the selective action of seed multiplication.
Several stocks of S23 perennial ryegrass were examined to see whether such a change occurred; Irish, Kent and Hunsballe were grown for comparison.
The characters recorded were date of ear emergence, winter requirement before heading, and leaf size, rate of leaf appearance, tillering and dry-weight production in the young seedling.
A slight shift towards earliness of heading occurred during seed multiplication, but no regular change in the other characters could be detected. The S23 stocks could readily be distinguished from Hunsballe and, less easily, from Irish, as early as the sixth leaf stage.
It is concluded that although considerable genetic variation for all these characters exists within the S23 stocks, changes during seed multiplication are not inevitable but depend on the management of the crop.  相似文献   

14.
The effects of variety, date of cutting flush growth and level of nitrogenous manuring on the crude-protein content of Italian ryegrass were studied on plots cut five times in 1958.
Raising the level of nitrogenous fertilizer from 174 lb. to 348 1b. N/acre reduced the percentage of dry matter from 0·5 to 2·0 and increased the percentage of crude protein in the dry matter from 0·9 to 5·1, with net increases in crude protein/fresh material of from 0·06 to 0·57%. Varieties showed consistent differences, the three Westcrwolth types, New Zealand H.I and New Zealand Italian being higher in percentage crude protein than Ayrshire, Irish, Danish and S22.
Culling the flush growth earlier resulted in an increased percentage of crude protein for that particular cut, but no overall increase in mean crude-protein percentage.  相似文献   

15.
The effects of applying nitrogen at different growth stages to S24 and S23 perennial ryegrass grown for seed were investigated in a series of field experiments from 1971 to 1976. These varieties of ryegrass were found to be insensitive to timing of nitrogen application from apex initiation to the stage when ears first emerged. However, if nitrogen application was delayed until about 30% or more of the ears had emerged, yields were lower compared with earlier applications, this effect being significant when nitrogen was delayed until 70–80% ear emergence because of a decrease in both numbers of fertile tillers and number of seeds per unit area. No advantages were found for splitting nitrogen applications between apex initiation and ear emergence.  相似文献   

16.
A series of six trials with eight strains of perennial ryegrass at two levels of manuring has now been completed. Results indicate that a moderate application of artificial manures gives a high degree of control over Gloeotinia temulenta infection. The degree of infection may be influenced by climatic conditions. Each strain has a definite inherent susceptibility or resistance to the disease. The most resistant strains are the commercial strains Irish Commercial and Devon Eaver; S24 is the most susceptible, followed by New Zealand Certified Mother Seed.  相似文献   

17.
Seven species or varieties of grass, and a mixture of 3 of them, were sown in pure swards and treated with 4 levels of nitrogenous fertilizer (0,17·5, 35 and 70lb N per acre per cut). Each species, and the mixture, was also sown with white clover. The experiment was cut 4 or 5 times per year. The effect of fertilizer on the yield of each grass was compared with the effect of clover on the yield of the grass/clover swards. Mean annual yields showed an approximately linear response to N; there was a small but significant fall in response to the highest level of N. Response among the species ranged from 20 to 30 Ib of dry matter per Ib N applied for the intermediate level of fertilizer and from 14 to 23 Ib for the final increment of fertilizer.
S37 cocksfoot, S48 timothy, S24 ryegrass, and a mixture of these grasses, were high yielding and responded well to fertilizer N; Irish ryegrass and Agrostis tenuis were less productive and gave poorer responses to N. S215 meadow fescue and S23 ryegrass were intermediate in yield and response.
There were no significant differences between the annual yields of the 8 grass/clover mixtures; the yields of the grass and clover components of each mixture were inversely related. The effect of clover on the yield of the grass/clover mixtures was estimated to be equivalent to the effect of an annual application of 205 lb N per acre to Agrostis tenuis and 120 lb N to S48 timothy. The fluctuations in annual yields were greater with grass/ clover mixtures than with grass swards receiving N.
The yields of grasses when sown with clover were in similar order to their yields when sown pure; but whereas the latter tended to fall from year to year, the yields of the grass components of mixtures (except Irish ryegrass) did not.  相似文献   

18.
The performance of timothy in mixtures with perennial ryegrass was assessed under a simulated intensive grazing management over two harvest years in 1974–75. Three seed rates of S23 perennial ryegrass were factorially combined with three rates of Scots timothy and compared with pure stands of each grass. All were sown with Huia white clover. When cut six times at monthly intervals and with an annual N input of 350 kg ha?1, there were no significant differences in total DM production in either year. The 2-year mean DM yield for the nine mixtures and six pure swards was 9·77 t ha?1 (range 9·34–10·16). Compared with the pure ryegrass swards, in both years the ryegrass-timothy mixtures produced earlier spring growth but were significantly lower yielding at the second cut. Over the first five cuts the proptortion of timothy in the three mixtures with 22·4 kg ha?1 ryegrass seed averaged 26% in the first year and 37% in the second. Corresponding calculated mean DM yields of timothy were 2·75 and 3·00 t ha?1. It is concluded that an early timothy variety is capable of competing with a late-heading perennial ryegrass in frequently cut swards managed to simulate intensive grazing. The strong development of timothy in the dry summer of 1975 suggests that in mixtures of late perennial ryegrass varieties, an early variety of timothy should be beneficial for its spring growth in grazed swards.  相似文献   

19.
Three experiments were carried out to examine the influence of grass seed-rate upon the amount of clover growing with different varieties of perennial ryegrass. The bred varieties S23 and S24 were compared with Irish ryegrass. A larger quantity of clover grew with Irish ryegrass than with bred varieties at any given seed-rate. If the varieties were to be compared in terms of herbage of similar clover content, then Irish ryegrass sown at 20 lb/ac had to be compared with S23 or S24 sown at about a quarter of that rate. Reducing the seed-rate of the bred varieties from 20 to 5 lb/ac had only a small effect upon yield of ryegrass, and this was offset by an increase in yield of clover. Since weed grasses also took advantage of low grass seed-rate, it is concluded that other factors in the management of variety trials must be so controlled as to produce a satisfactory clover content without too drastic a reduction in the seed-rate of any variety. The relationship between grass seed-rate and yield of clover varied markedly with the availability of moisture.  相似文献   

20.
This paper presents the results of 125 digestion trials with sheep fed herbage at different stages of growth from three clover-free pure grass swards. During 1958 and 1959, a study was made of the yield, leaf lamina, nitrogen, ash and digestible organic matter percentage ( D ) of first growths, of regrowths cut at monthly and two monthly intervals and of swards receiving various quantities of fertilizer nitrogen.
For first growths in the spring D remained almost constant until the ears started to protrude from the leaf sheaths and then fell rapidly at approximately 0·5 per cent per day. The D values for S 23 ryegrass were three weeks later than S 24 ryegrass, which correspond with later ear emergence of the latter. S 37 cocksfoot was always less digestible than S 24 ryegrass although both were at similar stages of growth. This difference in D also occurred in the regrowths. The D of monthly regrowths tended to fall with each successive cut, although in 1959 ryegrass values improved in the autumn.
Fertilizer nitrogen had little effect on D .
Despite the warmer spring and drier summer in 1959 and corresponding changes in production per acre there was little effect on D .  相似文献   

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