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Lolium perenne L. |
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Graminae |
Author: Alain Peeters |
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Perennial ryegrass (English), Ray-grass anglais (French), Englisches Raigras (German). Perennial plant, robust, medium size, hairless, cespitous. Stems erect, 10 - 60 (- 90) cm high. Blade folded when young, narrow (2 - 6 mm), rather long (3 - 20 cm), dark green, shiny on the lower side, veines well marked on the upper side. Ligule short, greenish to transparent. Auricles narrow. Sheaths of the inferior leaves red to purple red. Spike-like inflorescence. Spikelets applied on the axis by one of their sides. One glume per spikelet except on the top spikelet where there are 2. Glume shorter than the spikelet. Spikelets 6 10 (- 14) - flowered. Glume(s) exceed(s) usually the inferior lemma. Lemma without awn (not aristate) (see Lolium multiflorum). The weight of 1000 seeds is: diploids: 1.3 to 2.7 g (average seeds), tetraploids: 2.0 to 4.0 g (average to big seeds). Chromosome number: 2n = 14 (diploid), 2n = 28 (tetraploid). Physiological peculiarities: The plant tillers freely. The tiller density is very high in grazing (20,000 to 50,000 tillers/mē and even up to 70,000 talles/mē in case of sheep grazing) and lower in a cutting regime (6,000 to 15,000 tillers/mē) . The maximum number of leaves per tiller reaches 3. Almost 100 day.degrees are required to produce a new leaf. Each leaf has a lifetime of 300 day.degrees. The leaf turn-over is thus very fast. This is a competitive advantage in frequently defoliated covers. In spring, the first leaves that appear are relatively small. The next leaves increase in size until the maximum size is reached. In autumn, the opposite evolution is observed. The size of new leaves decreases with time. The roots are densely fasciculate. They can reach 1 - 1.5 m deep though the great majority of roots can be found in the first 15 centimeters of the soil. Root growth starts early in spring, almost 1 to 2 months before the leaves grow. It slows down in summer and restarts in autumn. It is thus parallel to the aerial part growth but it is earlier in spring. The roots have a lifetime of 2 to 3 months during the growing season. Perennial ryegrass is not alternative. It does not head the year of sowing. During the next years, there is always a certain percentage of new shoots after the first cut. The interval between the heading date of the earliest and the latest varieties is very important in this species. It can reach 1.5 month at low altitude in oceanic climate. Hybridizes with Festuca pratensis: x Festulolium loliaceum (Huds.) P. Fourn. and more rarely with Festuca arundinacea: x Festulolium holmberii (Dbrfi.) P. Fourn. Hybridizes with Lolium multiflorum: Lolium x hybridum Hausskn. These opportunities of hybridization are used in artificial breeding to get hybrids more resistant to drought (x Festulolium), more persistant (x Festulolium holmberii) or more productive (Lolium x hybridum). Typical of oceanic and mild climates. Sensitive to intense frostand to high temperatures. However less cold sensitive than Italian ryegrass but more sensitive to strong heat. Quite sensitive to shade. Often found in rainy climates and sensitive to drought but also very sensitive to winter flooding. Optimum on normally drained to cool soils. Dry or wet soils are not suitable. Optimum on nutrient-rich or very rich soils and slightly acid to neutral. Quite indifferent to soil texture. Loams and clays are nevertheless more suitable. Sands can be suitable if the water supply (irrigation or water table close to the surface) and the nutrient availability are sufficient. Rarer on peat soils. Native to Europe, temperate Asia and North Africa. Has become subcosmopolitan in temperate regions: introduced in North and South America, in Australia and in New Zealand. From the lowlands to almost 1200 m in the Alps. |