PRODUCTIVITY, PERSISTENCE AND RESPONSE TO NITROGEN OF ITALIAN RYEGRASS VARIETIES

The production of six varieties of Italian ryegrass was compared for three years by cutting 5 or 6 times during the growing season. All varieties showed falls in production of dry matter at high and low levels of N fertilization, but New Zealand HI and New Zealand Italian ryegrass showed significantly lower falls and gave top yields over the three years, in spite of severe frost damage in the first two. Crude protein and nitrogen absorption remained high at the lower level of fertilization (174–209 lb N/acre) and showed a fall only in the third year at the high level of N fertilization (348–418 lb N/acre).
The significance of the high response of the New Zealand varieties is discussed.     

NITROGEN AND ITALIAN RYEGRASS

In an experiment, described earlier (19) to study the regrowth of Italian ryegrass following a cut in late April, the N and nitrate-N content of herbage at 3 levels of applied N followed a similar pattern to that noted in earlier years in Cambridge. N content, however, did not fall to such a low level as in Cambridge. N yield fell later and less quickly than in Cambridge. The application of a very high level of N, 175 lb/ac (196 kg/ha), raised N and nitrate-N content and yield from the second or third week onwards. Changes with time in P and K content and yield were broadly similar to those for N. Level of N had only a small effect on content of P and K. Following the period of increase in yield of N, P and K, there was a period of about 6 weeks of relatively constant yield, followed by a fall. The content of N, P and K in fresh, rather than dry, herbage changed little with time from the fourth to the fourteenth week, despite major changes in crop maturity. The ratio P: K was little affected by level of N or time of harvest.     

EFFECTS OF METHOD OF ESTABLISHMENT ON TALL FESCUE AND ITALIAN RYEGRASS MIXTURES IN THE FOLLOWING YEAR

Tall fescue and Italian ryegrass mixtures react differently to management in the year of sowing. The decrease in yield of tall fescue and the increase in growth of red clover, caused by the use of a cover crop, was still evident in the following year. In both the spring grazing and total yield of the first harvest year, the Italian ryegrass/ white clover mixture was better than the tall fescue/white clover mixture when a cover crop was used. The reverse trend was recorded when the grass plus clover was sown without the cereal. In general, the addition of red clover to the tall fescue/ white clover, or Italian ryegrass/white clover mixture, increased the yield, but the magnitude of the increase was modified by management during establishment. The increase in total herbage yield and the reduction of white clover growth due to nitrogen application were both related to management in the year of sowing. Consideration should thus be given to method of establishment in the assessment of herbage seeds mixtures.     

NITROGEN AND ITALIAN RYEGRASS

This paper describes the regrowth of Italian ryegrass, following a cut in late April, measured by recording DM yields at weekly intervals up to 14 weeks. There were 4 levels of applied N: 25, 75, 125 and 175 Ib/ac (28, 84, 140 and 196 kg/ha). Rate of growth up to 10 weeks was compared with that recorded in similar experiments in Cambridge in earlier years and was found to be generally similar. The highest yields of DM and digestible organic matter were recorded after 11 weeks; beyond this stage there was a fall in yield. There was a large response to 75 Ib N compared with 25, a moderate response to 125 Ib compared with 75 (greater during the last 7 weeks than during the first 7 weeks), and little response to 175 Ib compared with 125. The time-saving value of N is noted. DM content was appreciably lower than in Cambridge, apparently because of both surface and internal moisture, but showed similar trends. In some of the early weeks, especially at high N, the crop appeared to be supplying water well in excess of livestock needs. In vitro digestibility was much affected by stage of growth and little affected by level of N.     

SPRING GROWTH OF PERENNIAL RYEGRASS AND COCKSFOOT

Preliminary results are given of experiments in progress to investigate the onset of spring growth and to compare spring growth rates in early- and late-types of perennial ryegrass and cocksfoot.     

THE EFFECT OF CUTTING HEIGHT AND CUTTING FREQUENCY ON THE PRODUCTIVITY OF AN ITALIAN RYEGRASS SWARD

Three cutting heights, 1, 3 and 5 in. (2.5, 7.6 and 12.7 cm), and three cutting frequencies, 3, 6 and 10 weeks, were imposed on a pure sward of Italian ryegrass (Lolium multiflorum) cv. Irish. Lowering the cutting height increased the yield of DM, digestible DM, crude protein and crude fibre. Increasing the interval between cuts increased the yield of DM, digestible DM and crude fibre. The results are discussed in relation to other research findings and to the management of short-term leys of Italian ryegrass.     

COMPARING THE OUTPUT FROM MIXTURES BASED ON PERENNIAL RYEGRASS AND ON MEADOW FESCUE

Herbage and livestock production from swards based on meadow fescue and on perennial ryegrass were measured over three years. The meadow fescue mixture had no practical advantages in terms of either annual output or seasonal distribution of production. This may have been due to inefficient methods of measurement or may have been peculiar to the management imposed, but it is considered that it was due to the depressing effects of timothy and cocksfoot on the meadow feseue.     

A COMPARISON OF THE EFFECT OF ITALIAN RYEGRASS AND TALL FESCUE MIXTURES ON THE FOLLOWING CROPS OF KALE AND BARLEY

The effects of preeropping with Italian ryegrass and tall fescue mixtures on marrow-stem kale (1st test crop) and barley (2nd test crop) were measured. Application of N to the grass/clover swards reduced the yield of DM, P, K, Na, Mg, crude protein and also the percentage crude protein in the kale test-crop. Following the tall fescue swards, the yield of DM, P, Na, Ca, Mg and E, crude protein and percentage crude protein in the kale were lower than after the Italian ryegrass swards. These effects were particularly evident in the kale stem. Interactions occurred which involved the method used to establish the herbage mixtures, the application of N to the swards and of fertilizers to the kale. These effects were complex, but the method of sward establishment could clearly affect the following kale crop grown several years later. The influence of grass swards on the second test-crop (spring barley) was much smaller than on kale. Precropping with Italian ryegrass or using a cover crop during grassland establishment reduced 1000-grain weight of barley. The crude protein percentage in barley grain was reduced by the compound fertilizer applied to the previous kale crop, particularly when no cover crop had been used during establishment of the herbage mixtures. The converse of these effects was recorded in the crude-protein percentage of the straw of the barley test-crop.     

A COMPARISON OF THE HERBAGE YIELD OF ITALIAN RYEGRASS AND TALL FESCUE MIXTURES IN THE SECOND AND THIRD YEAR AFTER SOWING

The annual yield of tall fescue was higher than that of Italian ryegrass in the third year after sowing, but the total yield of herbage from grass plus clover swards was similar.
In both the second and third year after sowing, the yield of herbage in the spring grazing was higher when fescue was used as the sown grass. The method of establishment of both tall fescue and Italian ryegrass affected the total and seasonal yield in the second and third year after sowing, but the magnitude of these effects was not nearly as marked as it was earlier in the life of the leys. In the second year after sowing, swards of both Italian ryegrass and tall fescue had a higher yield of total herbage and of white clover, and a lower ingress of unsown species, when established without a cover crop and grazed frequently in the year of sowing.
The inclusion of red clover did not increase total yield of DM in the second and third year after sowing, and it slightly decreased the yield of the tall fescue mixture in the third year following sowing when N was applied. S170 tall fescue was readily grazed by sheep in spring and autumn.
The apparent recovery of applied N varied with the mixture sown, and the management given during establishment.     

HEADING DATES OF S24 PERENNIAL RYEGRASS AND SPRING TEMPERATURES

For spaced plants of Lolium perenne cv. S24 at the Welsh Plant Breeding Station, Aberystwyth, and at the National Institute of Agricultural Botany, Cambridge, linear relationships were obtained between the recorded heading dates and (a) mean March earth temperatures at 30 cm depth and (b) mean March plus mean April earth temperatures at 30 cm depth. The residual standard deviations were ±2.97 days and ±2.65 days, respectively, A mean March earth temperature of 8°C predicted heading on 5 May, 6° C predicted heading on 12 May, and 4°C predicted heading on 20 May. For sites with an average April temperature significantly below 8.7°C a correction of +2 days per degree mean temperature difference in April had to be applied to these dates. These equations could be used to predict dates for 50% ear emergence in swards with a 50% confidence limit of ±22 days for sites in Central and Southern England and Wales. In certain years, cold, wet weather in May appeared to delay heading considerably at two Scottish sites.     

COMPARATIVE STUDIES OF PERENNIAL RYEGRASS, TIMOTHY AND MEADOW FESCUE

The voluntary intake by calves of perennial ryegrass, timothy and meadow fescue, when cut with a flail-type forage harvester and fed fresh, was measured. In 1963 a single management was used and rest periods between cuttings were of 10 or 11 days in April and May and 21 days in June to October. In 1964 the effects of managements with long (35–55 days) and short (15–25 days) rest periods were compared. The increases in rest periods within managements were made in June or July. The voluntary intake of the 3 grass species was not significantly different and the live-weight gains made on the species were similar in both years. Digestibility of all species was higher with the short rest periods than with the long ones and this resulted in higher intakes and liveweight gains from the short-rest-period management.     

THE CRUDE-PROTEIN CONTENT OF ITALIAN RYEGRASS

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.     

COMPARATIVE STUDIES OF PERENNIAL RYEGRASS, TIMOTHY AND MEADOW FESCUE

The growth of calves grazing pure swards of perennial ryegrass, timothy and meadow fescue at low grazing pressure was measured. Organic-matter intake was estimated on three occasions during the grazing season. In 1963 rest periods of 7 days in April and May and of 21 days in June-Octoher were used hetween 7-day grazing periods. In 1964 the effect of long (35–55 days) and short (15–25 days) rest periods hetween 3.5-day grazing periods were compared. There were no measurable differences in intake hetween the calves on the three grass species in 1963. In 1964 faecal production was higher with timothy than with the other species and with small differences in digestihility, the intake on this species was higher. The faecal production and intake were higher, hut not significantly so, with the long-rest management in the second year. The liveweight gains of the calves grazing the three species were similar in 1963; in 1964 gains with meadow fescue were lower than with the other species from 13 April to 22 June but this was the only significant difference. The results obtained on slaughtering the calves at the end of each summer are presented.     

NITROGENOUS FERTILIZATION OF ITALIAN RYEGRASS IN SPRING

A series of experiments in eastern Scotland, carried out over a 7–year period, on the application of N fertilizers to Italian ryegrass for producing early spring grass, indicated that maximum yields are likely to be produced if the fertilizer is applied not later than the middle of March in most seasons. Only rarely did application in February result in a loss of N and in reduced herbage yields. Italian ryegrass appears to be able to make some growth at temperatures below 40†F.
Increasing the rate of N application resulted in increased DM yield, the response averaging 9–4 lb DM per lb N. Herbage N concentration was increased by the additional N fertilizer. Nitro–chalk and ammonium sulphate were equally effective in producing early grass, irrespective of application date.     

COMPARATIVE STUDIES OF PERENNIAL RYEGRASS. TIMOTHY AND MEADOW FESCUE.

Hays made, mainly in May, from pure swards of perennial ryegrass, timothy and meadow fescue were fed to 8-month old steers in 1963 and to yearling steers in 1964. High-quality hay was obtained, but no significant differences in growth rate were observed between calves fed on hays from the 3 species. In 1963, barley (1.5 kg DM/ head per day) was fed, in addition to the hays, to half the animals and resulted in a significant increase in live weight gain. The productivity, in terms of liveweight gain/ unit area, of each species when managed for hay and‘zero grazing', or hay and grazing, was calculated. On this calculation perennial ryegrass was the most productive species.     

THE CONSUMPTION OF PERENNIAL RYEGRASS AND RED CLOVER BY GRAZING LAMBS

Groups of six-month old lambs, which were either experienced or inexperienced grazers, strip-grazed swards of S24 perennial ryegrass or Hungaropoly tetraploid red clover, at daily herbage allowances of 20 or 40 g OM/kg LW, in late August and September. The swards were similar in N content, but the weight of standing crop, and its digestibility, were higher on grass than on clover. Estimates of herbage intake were made in two successive periods of 19 days. Intake (g OM/kg LW) was lower at low than at high allowance (by 22% and 28% in periods I and II). and experienced grazers ate more than inexperienced animals (by 27% and 22%). Intakes on clover were 28% higher than on grass in Period I, but in Period II the difference was not significant.     

SEED FORMATION IN PERENNIAL RYEGRASS

During the interval from seed set to advanced shedding in a crop of S24 perennial rye-grass, a study was made of: seed drying, the increase in germinating capacity and weight of seed, and the shedding of florets. The seed in early-emerged heads dried more rapidly than that in later heads, and the seed in the upper parts of each spike was drier than in the lower parts. Seeds in early heads attained maximum germination values about 18 days after anthesis. The maximum value was lower in later heads and was not reached until approximately 26 days. Seed in early heads was 67% heavier than that in late heads and the basal florets in each spikelet contained heavier seed than more distal ones. The maximum weight of individual seeds was reached at about the same time in early-emerged and intermediate heads, at about 22 to 26 days after anthesis. Seed in late heads continued to inerease during the whole interval studied. Shedding began before seed reached maximum dry weight and continued at a constant rate. The combination of these processes led to the maximum yield of seed, of 100% germination, being obtainable over a period between 20 and 26 days after anthesis. Criteria are given which would permit this stage to be recognized.     

A QUANTITATIVE ANALYSIS OF GERMINATION AND EARLY SEEDLING GROWTH IN PERENNIAL RYEGRASS

Seedlings of perennial ryegrass were grown in soil and growth was studied up to 21 days from sowing. The shoot grew exponentially during this period. The weight of the whole plant fell to about 65% of the original weight of the caryopsis at about 9 days from sowing and did not regain this original value until about 16 days after sowing. Endosperm reserves were virtually exhausted within 14 days.
The interval between the 7th and 14th day appears to be critical in the establishment of the seedling, when conditions adverse to the development of a rapid rate of photosynthesis by the shoot could severely reduce seedling growth and the chances of survival.     

SEED FORMATION IN PERENNIAL RYEGRASS

In a seed crop of S24 perennial ryegrass the processes of anther exsertion and seed formation were measured in inflorescences which emerged early, intermediate and late. The peaks of anther exsertion in the three groups were simultaneous, although the proportion of heads showing anthers was lower in late heads.
Two-thirds of all florets set seed, but the proportion was lower in late heads than in the earlier groups. There was a slight fall in floret fertility in the upper spikelets, compared with those in the middle and at the base of the spike, and a marked reduction in fertility in the outer florets of each spikelet.
Factors likely to affect the efficiency of the pollination and fertilization process are discussed.