Alpine meadow grass
Poa alpina (Schröter, 1888)
BOTANY
Perennial, forms loose, usually grassgreen (on dry soil greyish-green) tight thickets, young shoots intravaginal, no stolons.
Culms are 10-40 cm high, erect or geniculate, smooth, glabrous, two to four glabrous nodes.
Leaf sheaths at the base of culms and young shoots clustered, rounded dorsally; smooth, glabrous with white margins, those of young shoots with margins connate for almost their entire length.
Ligule of upper culm leaves to 2.5-5 mm long, oblanceolate, with a membranous rim; those of young shoots 1-2 mm long, truncate, collar-shaped.
Leaf blades all growing at almost the same height, 3-12 cm long, 2-5 mm wide, flatbroadening, tip suddenly acuminating and shaped like a hood, glabrous, smooth, margins slightly scabrous. Ligule short and white.
Inflorescence a panicle, 3-7 cm long and up to 3 cm wide, loose to rather dense, in flowering period expanding, sometimes slightly nodding, pyramid-shaped. Lateral branches ramify individually or in pairs from smooth main axes, in flowering period strongly expanding or hunching down, in lower part no spikelets, thin, angular and scabrous. Rachis 0.5-2 mm long, angular and scabrous.
Five to ten flowered spikelets, 4-7 mm long, ovate, laterally compressed, green coated purple.
Floret is a 5-10-cm long, loose panicle.
SUITABILITY FOR RESTORATION
Alpine meadow grass grows naturally on dry or moist topsoil that is rich in humus, Ca2+ and bases with a pH between 5.6 and 7.2. In the Alps it grows at altitudes over 3 000 m. It is tolerant of high nutrients and shade. It is an excellent forage.
Alpine meadow grass is the most important pioneer plant on graded sites, except on highly acidic soil. It flourishes even in cold and dry habitats and has a good fixing of soil because of its tough roots. High seed development and early ripening, developing dense swards, highly resistant to wind, grazing and high nutrient content make it one of the most precious forages in high altitudes.
Seeds
SEEDS
Fruit of the husk 2-4 mm long, 0.6 mm wide and thick, ovate-lanceolate, pointed.
Lemma veined, strongly keeled, margin membranous, dorsally and on marginal veins long, white, spiky hairs, adaxially puberulous. Palea hollow, tightly clasped by the lemmas.
Rachis tapered basally, truncate angularly at the apex.
Fruit 1-2 mm long, 0.6-0.8 mm wide, triangular, ventrally slightly recessed.
Thousand seed weight: 0.5-0.7 g.
REQUIREMENTS
(soil and climate)
For seed production this species has no special soil requirements. However, the supply of bases and calcium should be sufficient. Moist, cold soil and soil that desiccates in summer should be avoided. It is important to choose a habitat with low weed competition. Alpine meadow grass has a very slow juvenile development and is not very competitive. Chemical weed control should only be used with parsimony. Sites with a high presence of annual meadow grass (Poa annua), rough meadow grass (Poa trivialis) and crab grass (Digitaria sanguinalis) should be avoided.
CULTIVATION
As is common in the cultivation of grass seeds, a fine, crumbly seedbed is required. Open sowing is possible but may result in high weed infestation in spring. Seeding should be carried out until the beginning of July in order to obtain a satisfactory development of single plants until autumn. Open sowing in summer requires irrigation in drought periods.
Because of the plant’s slow juvenile development, winter cereals are not suitable as a cover crop. A thin cover crop population (e.g. summer barley, durum) is important. If the population is too dense the development of single plants is suppressed which results in poor tillering in autumn. In this case increased weed infestation and reduced crop yields in the first harvesting year are to be expected. Linseed as a cover crop has proved worthwhile. Its slow juvenile development means that cultivation of alpine meadow grass should be undertaken immediately after seeding the cover crop.
Seeds have a good seed flow and are suitable for all common seeding systems. It is important that seeds are applied flat and evenly at a maximum depth of 0.5 cm. A compact topsoil is important for good germination.
Seed rate: 6-10, mean value 8 kg/ha with excellent seeding technique, otherwise higher amounts are required to obtain regular stands.
Row spacing: 12-15 cm depending on the construction of the sower. The sowing tubes are often removed for broadcast sowing on the surface, followed by currying.
FERTILIZATION
Alpine meadow grass is relatively undemanding. For a satisfactory crop a sufficient nutrient supply is necessary.
Phosphorus and potassium: on soils with an intermediate supply of phosphorus and potassium, fertilization with liquid or solid manure is sufficient. For soils with good nutritional content, amounts of 50-70 kg/ha P2O5 and 70-120 kg/ha K2O are sufficient, depending on yield levels.
Nitrogen: after harvesting the cover crop and cutting the stubbles an application of 30 kg/ha N-total is recommended in order to achieve optimal development until autumn. The amount of nitrogen, necessary for seed development should be applied in autumn (70 percent) and in early spring (30 percent). Late fertilization in spring mainly stimulates the development of leaves. The total amount of nitrogen should be between 70-100 kg/ha, depending on climate and soil conditions.
MAINTENANCE AND WEED CONTROL
The cutter bar of the harvester should be set very low and stones should be removed beforehand.
Alpine meadow grass is tolerant of herbicides. For application of hormonetype and broad-spectrum herbicides see Table 3. The use of herbicides is necessary even for low weed infestation. Early application is important because high weed competition has a disproportionately high impact on crop yields.
Weed infestation by Poa annua (annual meadow grass) is a specific problem, which may lead to severe contamination of seeds and result in poor seed quality. Selective weed control is possible when weed infestation is low. However, it is not possible to give general instructions. An expert survey is necessary in order to recommend a specific composition.
Diseases: particularly in autumn, before the second harvest, an accumulation of rust diseases may occur. In this case application of customary broad-spectrum fungicides for seed cultivation is necessary to avoid substantial decreases in yields the following year. Cutting in late summer is helpful but should not substitute the application of fungicides because this could lead to high weed infestation. Alpine meadow grass has a low biomass production. Therefore, its use as forage is not economical. However, cutting is necessary in the first growing year.
HARVEST AND YIELDS
Resistance to lodging: unproblematic.
Shattering tendency: very high.
Ripeness: branches of panicle and upper part of culm change colour to yellow or light brown. Grains change colour to greyish-brown and shatter easily when touched. Ripeness is not very compact. When 60-80 percent of the grains are fully ripe, threshing should be carried out. During this period, the state of ripeness should be checked up to twice a day.
Ripening period: beginning or middle of June depending on the site.
Threshing is usually done from the root. Swath threshing is possible, although, the amount of chaff and undesirable seeds will increase. The cutter bar should be set very low in order to take up the panicles close to the ground. The settings for threshing are usually unproblematic. The rotational speed of the threshing drum can vary between 800 and 1 000 U/min with close settings of the threshing concave. The fan should be set very low; the wind produced by the threshing drum is usually sufficient.
Crop yields: crop yields reach between 150 and 600 kg/ha in practice. Maintenance and weed control are crucial for yield levels. In existing seed production the average crop yield has been 300 kg/ha. In populations with low weed infestation a second and third harvest year are possible. In this case a decrease in crop yields of 20-40 percent is to be expected.
