Tetraploid Perennial Ryegrass Research Articles

The effect of the weather on the drying rate of cut diploid and tetraploid perennial ryegrass (Lolium perenne L.) and diploid hybrid ryegrass (Lolium perenne×L. multiflorum)

AbstractThe drying rate of cut diploid and tetraploid perennial ryegrasses (Lolium perenne L.) and a diploid hybrid ryegrass (Lolium perenne×L. multiflorum), and associated meteorological characteristics, were studied in the field for three successive years: 1988, 1989 and 1990. Meteorological elements measured were: air temperature (at 0·1 in and 1·5 in height), dew point temperature (at 1·5m height), temperature within the grass sward, grass surface temperature, global radiation and wind speed (at 2 in height).Apart from the weather, the drying depended on the grass species and the yield. Hybrid ryegrass had a lower initial moisture content at cutting in the morning than perennial ryegrass. Also, the hybrid ryegrass dried faster than the perennial ryegrass. Within the same varieties a low yield dried faster than a high yield. Frequent tedding did not influence the rate of drying. The temperature within the grass swath approached the air temperature at 1·5 m. The grass surface temperature was greatly affected by global radiation. Increasing wind speed had an adverse effect on the drying rate of grass.

A comparison of diploid and tetraploid perennial ryegrass and tetraploid ryegrass/white clover swards under continuous sheep stocking at controlled sward heights. 2. Animal production

AbstractPerformance of continuously stocked Mule ewes nursing Suffolk‐cross twin lambs over three grazing seasons, between April and August, was compared on swards of N‐fertilized diploid perennial ryegrass (D), tetraploid perennial ryegrass (T) and tetraploid perennial ryegrass with white clover (TC), the latter receiving no fertilizer N. Sward height was maintained by variable stocking rate close to a target of 4–6 cm (constant treatment) from turnout and compared in July and August with a rising sward height treatment (target 6–8 cm).Lambs on TC swards had significantly higher (P <0·001) liveweight gains compared with lambs on T swards by 41 gd‐1 in April–June and by 68gd‐1 in July‐August. Live weight and body condition score of ewes in August were significantly higher (P<0·001) on TC compared with T swards, by 11·3 kg and 0·75 respectively. Rising sward heights in July–August increased live‐weight gain of lambs compared with constant sward heights by 102, 39 and 54gd‐1 in consecutive years, associated with sward height increases of 0·9, 0·5 and 0·6cm respectively. Rising sward height increased ewe live weight and body condition score by 5·1 kg and 0·3 respectively, compared with results from constant sward heights. Effects of sward height and sward type were additive.T swards had a significantly (P<0·01) 16% greater overall lamb output than the D swards due mainly to a 10% higher achieved stocking rate. Stocking rates of ewes on TC vs T swards were 40, 13 and 12% lower in April‐August in successive years. The higher liveweight gain of lambs on the TC swards resulted in lamb outputs of 76, 105 and 101% of the T swards in successive years, showing that grass/clover swards containing over 20% clover could produce similar lamb output ha‐1 to grass swards given 150–180 kg N ha‐1.

A comparison of diploid and tetraploid perennial ryegrass and tetraploid ryegrass/white clover swards under continuous sheep stocking at controlled sward heights. 1. Sward characteristics

AbstractTwo 1·0 ha plots of a late‐heading diploid perennial ryegrass (var. Contender) and a late‐heading tetraploid ryegrass (var. Condesa), and two 1·4 ha plots of the tetraploid with Aberystwyth S184 small‐leaved white clover, were direct sown in May 1987. Over the three years 1988–90 they were continuously stocked by Mule ewes with Suffolk‐cross twin lambs, from early April to the end of August, at a target sward surface height (SSH) of 4–6 cm on one set of plots (constant swards) and, on the other set, al 4–6 cm rising after June to a target 6–8 cm (rising swards). The heights were achieved by variable stocking. Fertilizer N was applied only to the grass plots at the rate of 150‐ 180kgN ha‐1 annually.SSH was mainly within the target 4–6 cm, after higher initial heights at turnout in 1988and 1990. Mean heights of the constant swards (April‐ August) averaged 5·53, 4·43 and 5·04cm in the three years. The rising swards (July‐August) increased in height over the constant swards by an average of 0·88, 0·48 and 0·55 cm, in successive years.Clover content of the herbage mass dry matter in the grass/clover swards increased over each grazing season to average 13·0, 26·5 and 21·2% in the three years, with a high mean stolon density of 130 in m‐2 in August 1990. Ryegrass tiller densities in year 3 were 23% higher in the diploid than in the tetraploid swards, which had 43% more than the 10000 tillers m‐2 of the tetraploid ryegrass/clover swards.It is concluded that the combination of a densely stoloniferous small‐leaved clover with the open growth habit of a tetraploid ryegrass can achieve swards of high clover content under continuous sheep stocking.

Component yields and quality of binary mixtures of lucerne and perennial, Italian or short rotation hybrid ryegrass

AbstractStudies were conducted to characterize sward dynamics of lucerne (Medicago sativa L.) and perennial, Italian or short rotation hybrid rye‐grass (Lolium perenne L. and L. multiflorum Lam.) binary mixtures under hay management. Lucerne/timothy (Phleum pratense L.) mixtures were included as controls. The study was conducted on two farms in central Pennsylvania, USA on Hagerstown silt loams (fine, mixed, mesic hapludalf). Total dry matter yield, grass yield and yield of digestible dry matter were higher for tetraploid perennial and tetraploid Italian ryegrass mixtures than for timothy mixtures. Seasonal production differed for the three kinds of ryegrass. Italian ryegrass dry matter yields were higher in cuts 2 and 3 than perennial ryegrass yields. Grass yields represented 34%, 24% and 12% of total yields of the Italian, perennial or short rotation, and timothy mixtures, respectively. However, herbage in vitro dry matter digestibility of Italian was lower than that of perennial ryegrass.The tetraploid perennial ryegrasses Grimalda and Reveille had high‐ranking N concentrations more frequently than other cultivars, while Bar‐vestra and Reveille tetraploid perennials and Bison short rotation ryegrass had high‐ranking dry matter digestibility values more frequently than the other cultivars. Perennial ryegrass cultivars and Lipo tetraploid Italian ryegrass persisted well for 4 years and produced higher yields with a lower weed content than timothy mixtures. It is concluded that perennial ryegrasses and Lipo Italian ryegrass should be recommended over timothy, as companion grasses with lucerne.

A rapid method by flow cytometry for estimating persistence of tetraploid perennial ryegrass in pasture mixtures with diploid perennial ryegrass

A simple and rapid method for the estimation of the proportion of diploid and tetraploid perennial ryegrass in a mixed sward is described, based on the measurement of the nuclear DNA content of the leaf tissue cells by flow cytometry. The error of estimation was less than 5 %.

Effects of fishmeal supplementation of baled grass and clover silages fed ad libitum to lambs

Sustainable clover dominant swards have been developed for upland UK sheep grazing conditions by sowing a mixture of tetraploid perennial ryegrass cv Condesa and small leaved clover cv Aberystwyth S184. These pastures have produced equal output to Condesa only swards given 150-160 kg N/ha/year. Lamb liveweight gain from April to August was increased by 50 g/day on the grass/clover vs grass swards. A comparison of the suitability of these grass/clover and N-fertilised grass only swards for silage was undertaken in order to assess silage yield potential and silage feeding value. The enhanced animal performance of lambs on clover has been partly attributed to the higher levels of dietary amino acid clover has been observed to provide. In order to quantify this effect sufficient supplementary fishmeal (60 g/day) to fully meet tissue N needs was fed to lambs on the grass/clover and grass silages and responses in lamb performance compared.

Evaluation of the use of a small leaved clover as an alternative to fertiliser-N on tetraploid and diploid perennial ryegrass swards grazed to controlled sward heights by ewes and lambs

Lamb performance at grass falls in July/August on upland farms. Allowing sward height to rise has been recognised as having an ameliorating effect [Keeling, 1987). The objective of this trial was to determine the influence of both sward quantity (sward height) and sward quality [sward type) on ewe and lamb performance from mid April to September. A further objective was the evaluation of clover as an alternative to nitrogen fertiliser.Three contrasting perennial ryegrass based swards were established in May 1987 for use in 1988 and 1989: a late heading diploid variety (D). CONTENDER and a late heading tetraploid variety [T) CONDESA sown alone or with S184 small leaved white clover [TO]. [D] swards represent the control being the normal upland pasture type. [T] companion ryegrass varieties have higher palatability and intake characteristics and, producing fewer tillers, are a compatible companion grass to white clover. Small leaved white clover was used owing to its higher persistency and dry matter production under continuous sheep grazing.

The Persistence of Tetraploid Perennial Ryegrass in a Mixture with Diploid Perennial Ryegrass

AbstractAn investigation was carried out into the survival of two tetraploid varieties of perennial ryegrass (Lolium perenne L.), sown in a mixture with a diploid and very intensively grazed for over five years.Mixture M1 consisted of the late heading varieties Meltra and Vigor, and mixture M2 of the early heading varieties Merlinda and Melino.The ploidy was determined by microscopic analysis.The share of the tetraploid component decreased in both mixtures. The decrease was more pronounced in the early heading mixture. Information was also sought on the technique of sampling such swards.

Self-incompatibility in ryegrass VII. the determination of incompatibility genotypes in autotetraploid families of Lolium perenne L.

The two locus gametophytic self-incompatibility system of the grasses entails a maximum of four different S-Z specificities in the diploid pollen of tetra-ploid individuals. It is not known for certain whether only one S-Z pair in such pollen needs to be matched by the same pair in the stigma for incompatibility to occur (hypothesis 1) or whether all such pairs have to be matched (hypothesis 2). This paper, the first of three, concerns the results obtained from the application of the first stage of a three-stage procedure for the analysis of self-incompatibility in tetraploids. Pollen from diploids of known genotype is applied to the stigmas of related tetraploids in order to determine the incompatibility genotypes of the latter. The results obtained from two families of tetraploid perennial ryegrass show that the 35 legitimate plants examined fell into 18 of the expected 81 different incompatibility classes, and that the gametic segregation ratios of the parents of these families were consistent with the assumption that the chromosomes segregate at random with respect to the incompatibility loci in tetraploid ryegrass. Furthermore, since it was possible to recognise plants of genotype S3456Z3456 and S3356Z3356, the alleles must act independently in the stigmas of tetraploids with no dosage effects.

A comparison of diploid and tetraploid Lolium perenne L. sown alone and in mixtures with particular reference to the effect of treading

SUMMARYDiploid and tetraploid perennial ryegrass (Lolium perenne L.) cultivars were compared sown alone and in mixtures, with and without cattle treading for 4 years after the year of sowing. Data were also obtained on the survival of tetraploid ryegrass in mixtures under farm conditions.The overall effect of treading was not large but annual yield of dry matter was reduced by cattle treading every year (mean 9%). Sheep grazing and treading also reduced yield below that of cut plots. The reduction depended on the sampling date and varied from 40% to nil. In two instances treading increased yield.Interactions between cultivars/mixtures and treading occurred in 22% of the occasions when treading influenced yield. In the first harvest year the tetraploid Reveille was more resistant to treading than the diploid S. 24. In older swards (3rd and 4th harvest year) the situation was reversed. The occurrence of cultivar/mixtures × treading interactions and the effect of mixing diploid and tetraploid ryegrass on resistance to treading were unpredictable.The evidence from the main trial and the farm survey showed that tetraploid ryegrass could persist for at least 3 years after the seeding year when exposed to periods of high stock density. In addition, in mixtures there was no initial domination of the sward by either component when cut or when subjected to severe treading. In the third harvest year of the experiment the proportion of tetraploid ryegrass decreased considerably. Total yield of the mixtures was not significantly different from that of pure swards of the components though seasonal distribution of yield could be modified. The contribution of tetraploid ryegrass to swards up to 4 years old was in proportion to the percentage of tetraploid in the seeds mixture. Evidence from both the experiment and farm survey demonstrates that it is possible to exploit advantages claimed for tetraploids in mixtures for three harvest years without detrimental effect on sward performance.

Hybrids between tetraploid Italian and perennial ryegrass

Hybridization frequency was investigated between tetraploid perennial and Italian ryegrass (Lolium perenne X multiflorum) without emasculation by using genetic markers. The Italian phenotypes, fluorescentroots and awned florets, were dominant. About 82% of the plants in perennial X Italian and nearly 93 % of the plants in the reciprocal crosses were hybrids. The hybrids had a high multivalent frequency and involved homoeologous chromosome pairing. Aneuploids with 2n = 26, 27 and 29 chromosomes were present. The hybrids were highly fertile. The cytogenetic behaviour of these allopolyploids suggested that the genomes of the parental species have undergone little repatterning and have free genetic exchanges. The species maintained their self-incompatibility and cross-compatibility at the tetraploid level.

Germination in vitro of ryegrass pollen grains

Pollen grains of diploid and tetraploid Italian, perennial and hybrid ryegrass (Lolium spp.) germinated on 20% sucrose solution with 10 ppm each of CaCl2, H3BO3 and EDTA. Pollen tubes emerged within 2–3 minutes after sowing and completed full growth within 1 1/2 hours. The tube elongation showed the expected linear growth rate. The tubes of the haploid pollen grains grew faster (3.9 μm/minute) than that of the diploid (3.3 μm/minute). Diploid pollen grains germinated better on 25% than on 20% sucrose solution. Up to 25% of the diploid pollen produced two tubes.

Cross compatibility between diploid and tetraploid perennial ryegrass (Lolium perenne L.)

A number of crosses were made between diploid and tetraploid Lolium perenne plants in order to determine the degree of cross compatibility between the two different ploidy levels. The range of hybridization undertaken involved diploidxdiploid, and tetraploid x tetraploid control crossings, diploid x tetraploid crosses, tetraploid x diploid crosses and mixed pollinations. The seed set, the germination capacity of resultant hybrid seeds, and the chromosome constitution of derived seedlings was determined. In addition attempts were made to culture 12 day-old hybrid embryos from the diploid x tetraploid and reciprocal crosses.

The Value for Agricultural Use of Grass Seed Mixtures of Species and Varieties in Comparison with Single Varieties

22 commercial mixtures were compared in a mowing trial (complete block design, 2 replicates) in 4 locations during 3 consecutive years. These mixtures contained mainly diploid and tetraploid varieties of Lolium perenne L.. Festuca pratensis Huds., Phleum pratense L. and Trifolium repens L. were also included at various times. 250 - 400 kg N.ha-1.year-1 was used. Dry matter yield (DM-yield), disease resistance and persistence were evaluated. Similar results were obtained for all three performance parameters (DM-yield, crown rust resistance and persistence) of the mixtures as compared with the individual components.
 There was almost no relationship between the percentage of diploid perennial ryegrass in the mixture and its persistence (R2 = 0.18). Similar results were obtained for the relation between the percentage of tetraploid perennial ryegrass in the mixture, as well as for disease resistance of the mixture in late summer (R2 = 0.25).