Lolium perenne L.

Symbol: 
LOPE
Group: 
Monocot
Description: 

Perennial, cool-season bunchgrass native to Europe, temperate Asia, and North Africa. Widely distributed throughout the world, including North and South America, Europe, New Zealand, and Australia. Important in global forage/ livestock systems. High palatability and digestibility make it highly valued for dairy and sheep forage systems. Often the preferred forage grass in temperate regions. Characteristics include high yield potential, fast establishment, suitability for reduced-tillage renovation, and use on heavy and waterlogged soils. In the USA, perennial ryegrass is used predominantly in the coastal Northwest, irrigated intermountain valleys of the West, the Midwest, and Northeast.

Uses: 
Pasture
Hay
Silage
Soil Protection (Cover Crop)
Wildlife

Species Selection Characteristics

Annual Precipitation (inches): 
20 to 24
24 to 28
28 to 32
32 to 36
36 to 40
40 to 50
50 to 60
60 to 70
70 to 80
80 to 100
100 to 120
120 to 140
140 to 160
> 160
Plant Hardiness Zones (cold tolerance): 
3b
4a
4b
5a
5b
6a
6b
7a
7b
Heat Zone (July Mean Max Temperature): 
< 14 °F
14 to 18 °F
18 to 22 °F
22 to 26 °F
26 to 30 °F
30 to 34 °F
34 to 38 °F
38 to 42 °F
42 to 46 °F
46 to 50 °F
50 to 53 °F
53 to 56 °F
56 to 59 °F
59 to 62 °F
62 to 65 °F
65 to 68 °F
68 to 71 °F
71 to 74 °F
74 to 77 °F
77 to 80 °F
80 to 84 °F
84 to 88 °F
88 to 92 °F
Soil pH Tolerance: 
Strongly acid, 5.1–7.3
Moderately acid, 5.6–7.3
Moderately acid to moderately alkaline, 5.6–8.4
Slightly acid to moderately alkaline, 6.1–8.4
Near neutral, 6.1–7.3
Soil Drainage Tolerance: 
poorly drained
somewhat poorly drained
moderately well drained
well drained
Flooding Tolerance: 
7-30 days
Soil Salinity Tolerance: 
Moderately tolerant, 3–6 dS/m

Identification Characteristics

Type: 
Grass
Growth Season: 
Cool

Growth Habit and Stand Life

Habit: Erect bunchgrass, graminoid. It resembles annual ryegrass (Lolium multiflorum Lam.), although perennial ryegrass has more leaves in lower parts of the plant canopy, it’s collar and blade are more narrow, and lemmas are awnless.

Stand life: Moderate length perennial, although it can behave as an annual, short-lived perennial, or perennial, depending on environmental conditions. Normally considered a short-lived perennial.

Life Cycle: 
Short-lived perennial

Climate and Soil Suitability Zones

Climate Tolerances: 

Climate: Requires moderate winter and summer temperatures. [USDA Plant Hardiness zones 6a-8a; Jan mean minimum of -10 °F, -23.3 °C); American Horticultural Society Heat Zones 3-6 (<60 days above 86 ˚F (30 C)]. 

Requires 40-60 inches (1000-1500 mm) of precipitation or irrigation. 

Soil Tolerances: 

Soil: Tolerant of soil drainage categories well-drained to poorly-drained. 

Tolerates strongly acid to moderately alkaline soils (pH 5.1-8.4). 

Moderately tolerant of saline conditions (3-6 dS/m). Somewhat tolerant of water-soluble aluminum (persisted at 1-2 ppm Al3+).

Quantitative Tolerances: 

Climate suitability characteristics in the following table are based on field experiments and forage agronomist experience. Soil factor data are based on values provided in Chapter 3 of the NRCS Range and Pasture Handbook (https://www.nrcs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb1043060.pdf).

Climatic and soil factor values for well-suited, moderately-suited, and marginally suited classifications.

  July Max Temp (°C) January Min Temp (°C) Annual Precipitation (mm) Soil pH Soil Drainage Class Soil Salinity (dS/m)
Well-suited 30 -10 600 5.75-7.5 MWD 2
Moderately-suited 32 -15 500 5.5-7.75 SPD-MWD 8
Marginally-suited 34 -20 400 5.25-8.0 WD 8

Response functions were developed from these tabular values using Rstudio scripts, with parameters provided for climatic and soil GIS spatial data layers.

Suitability Maps

To create highly detailed and accurate species suitability maps it was necessary to change from a qualitative description of plant characteristics to an approach that defines tolerances quantitatively. Tolerances to climatic and soil factors were defined (Table 1) and used to map suitability based on summary publications (Moser et al., 1996) and expert knowledge of forage scientists. 

Moser, L.E, D.R. Buxton, and M.D. Casler, Eds. 1996. Cool Season Forage Grasses. American Society of Agronomy Monograph 34. 841 pp. ASA, CSSA, and SSSA, Madison, WI. 

Suitability patterns for forage species are caused by different factors in different locations. Low winter temperatures limit the northern range of many species, while low precipitation limits the western range of species in the semi-arid west. Low summer temperatures limit the range of species with increasing elevation while high summer temperatures limit the range in the desert southwest and hot and humid southeast. Soil characteristics (pH, drainage, and salinity) also limit the suitability zones of forage species. However, soil amendments (liming and drainage tiles) can alleviate many of these limitations.  Thus, NRCS Soil Survey data should be informed and revised by management mitigations. 

GIS software allow creation of highly detailed and accurate species suitability mapping based on biophysical characteristics of the region and plant characteristics (Hannaway et al., 2005). Precipitation and maximum and minimum temperature climate grids are now available for annual and  monthly periods. Soil type, depth, drainage, pH, salinity, and alkalinity information was obtained from the NRCS STATSGO2 database. Species characteristics were provided by forage experts.

Hannaway, D.B., C. Daly, L. Coop, D. Chapman, and Y. Wei. 2005. GIS-based Forage Species Adaptation Mapping. pp. 319-342. In: S.G. Reynolds and J. Frame (eds). Grasslands: Developments, Opportunities and Perspectives. FAO and Science Pub. Inc., Rome, Italy.

Maps

Nine maps were developed; 1) 30-year long-term July maximum temperature 2) 30-year long-term January minimum temperature, 3) 30-year long-term annual precipitation, 4) soil pH, 5) soil drainage, 6) soil salinity, 7) combined climate factors, 8) combined soil factors, and 9) combined climate and soil factors.

Climate: Tmax, Tmin, Ppt, Combined

Soil: pH, Drainage, Salinity, Combined

All Factors

Yield Potential and Production Profile

Spring and fall are the seasons of best growth; during the hot summer months, perennial ryegrass becomes dormant. Maximum growth occurs between 68 and 77 °F (20-25 °C). Perennial ryegrass is more sensitive to temperature extremes and drought than is annual ryegrass. Even with irrigation or abundant rainfall, production suffers when daytime temperatures exceed 87 °F (31 °C) and nighttime temperatures exceed 77 °F (25 °C).

Perennial ryegrass is less winter-hardy than orchardgrass and tall fescue and less drought-tolerant than smooth bromegrass. Studies in Wisconsin, however, show it is able to overwinter in colder climates, even where snow cover is unreliable. In the Pacific Northwest, perennial ryegrass will survive most winter weather conditions.  However, during very harsh winters, it may winter kill.  

Forage yields of 6.5 to 7.5 tons/acre (16-18.5 metric tons/ha) are possible with proper management and a 120-130 day growing season.

 

Cultivars

Many types of ryegrass exist, because most cultivars do not self-pollinate but easily cross with other Lolium and Festuca species. Persistence of perennial x annual hybrids falls between that of annual and perennial types. As a result, these crosses are called intermediate, or short-rotation ryegrasses.

There are both diploid and tetraploid forage-types. Tetraploids have fewer, but larger tillers with wider leaves, resulting in more open sods. Both the seed and seedlings of tetraploids are larger, but growth rate is greater for diploids. Tetraploids are less winter-hardy and less persistent than diploids. Cultivars are grouped into three maturity categories: early, intermediate, and late. These groupings are somewhat helpful, but there is substantial overlap among them.

 

Management Level Required

Suitable Management Level: 
High
Medium

Quality and Antiquality Factors

Quality Factors: 

Quality: Perennial ryegrass is high quality forage and its high digestibility makes it suitable for all types of grazing livestock.  

  • Very high palatability
  • Quick establishment
  • More persistent than annual ryegrass
  • Recovers rapidly to grazing, tillers extensively
Anti-quality Factors: 

Antiquality: Ryegrass staggers is an important disorder associated with turf-type perennial ryegrass. For hay, silage or pasture, select a non-endophyte containing forage type perennial ryegrass. Staggers is caused by a fungal endophyte (Neotyphodium lolii Latch, previously known as Acremonium lolii Latch). This is a different endophyte from the one associated with tall fescue. In the early stages, affected animals have difficulty flexing their legs and thus have an unusual gait. In severe cases, animals have difficulty walking and may fall repeatedly. Convulsions and death may occur. There is no treatment for ryegrass staggers except to reduce consumption of infected plants.

  • Short stand life
  • Vulnerable to drought, high temperatures
  • Susceptible to winterkill
  • Fungal endophyte present in grass associated with neurological disorder in livestock which consume it
  • Bloat.  Perennial ryegrass does not cause bloat.

  • Grass tetany. As a cool-season forage, magnesium levels will be reduced in early spring and potassium levels will be elevated.  Thus, growing perennial ryegrass with a legume will reduce the potential for grass tetany (hypomagnesemia). 

     

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Resources

Publications: