Smooth brome, awnless brome
Bromus inermis (Schröter, 1888)
BOTANY
Perennial species, 30-140 cm high, lowdensity cespitose because of highly ramified rhizomes.
Culms are stiff, erect and inflorescence symmetrical.
Leaf sheaths glabrous, more or less densely ciliated.
Ligules 1-2 mm long, greenish-white, truncate, lacerate.
Leaf blades 2-10 mm wide, light green to grey-green; adaxially mostly glabrous with wax coating (greasy), abaxially keeled and scabrous especially towards the apex. Margins serrate; leaf base strong, bright, often undate.
Inflorescence a panicle, grand, 10-15 cm long, widely expanding, partly one-sided.
Spikelets large, slender, multiflowered, 15-25 mm long.
SUITABILITY FOR RESTORATION
This Eurasian species occurs in the Alps, in the foothills and sparsely in montane zones; it prefers a continental climate. In central Europe - excluding the eastern parts of its distribution area - smooth brome mainly grows on artificial sites, such as slopes along roads and waysides. It is fairly tolerant to temporary flooding and low salinity. The species grows on loam that is sparsely covered with vegetation, warm in summer, moderately moist, rich in minerals, sandy or pure, with a pH of 6.1-7.2.
Because of its rapid juvenile development and its sarments, the species is suitable for restoration on slightly inclined slopes in warmer regions. It is an important forage in warmer, humid continental regions (e.g. on soils that are rich in sodium bicarbonate, as in Hungary and the United States).
SEEDS
Fruit 10-13 mm long, 1.5-3 mm wide, and 1 mm thick. Oblong, flat, with only a short awn and often without one.
Lemma a little vaulted, seven-veined; midvein quite distinct.
Awn 4-6 mm long, erect, originating below the apex of the lemma. Palea flat, both keels with dense short hairs, colourless.
Thousand seed weight: 2.3-2.7 g.
REQUIREMENTS
(soil and climate)
Smooth brome is extremely undemanding. Intermediate to light soils that are rich in humus and drier sites are suitable. It is important to select sites with little weed competition, because of limited possibilities for the use of specific herbicides.
Seeds (Blaschka, A.)
CULTIVATION
This species needs a well-prepared seedbed.
Open sowing is recommended, (this is possible until the end of June if irrigation is available).
Smooth brome is moderately tolerant if grown underneath a cover crop. Therefore populations of spring corn should be low density; linseed oil flax is recommended.
Seed depth: 1.5-2 cm maximum.
Seed rate: 12-15 kg/ha.
Row spacing: 25-30 cm. Broadcast sowing is also a practical alternative.
FERTILIZATION
Smooth brome requires a great deal of nutrients.
Phosphorus and potassium: on soils with an intermediate phosphorus and potassium content, basic fertilization with manure (liquid or solid, 20-30 tonnes/ha) is sufficient in autumn. If the soil content is adequate, fertilization with 60-80 kg/ha P2O5 and 100-140 kg/ha K2O is considered sufficient, depending on the yield.
Nitrogen: after harvesting the cover crop, or at sowing, fertilization with about 50 kg/ha of N-total is recommended in order to obtain best development until autumn. A certain amount of nitrogen is necessary for the formation of seeds: 70-100 kg/ha of N-total should be added in autumn and early spring.
If fertilization in spring is carried out too late, it is principally the leaf mass that is stimulated.
MAINTENANCE AND WEED CONTROL
Smooth brome germinates quickly.
There is then a short stagnation in its growth rate, followed by rapid juvenile development. Until autumn of the seeding year this species sometimes forms high-density populations. However, the timely use of herbicides should be emphasized. Particular control of weed grasses can only be carried out by the control of single plants or - in favourable years - by the temporary use of wiping wicks.
Mechanical weed control by means of curry combs is well tolerated.
Leaf spot diseases: in some years a more marked decay is possible. In this case the timely use of broad-spectrum herbicides or additional cutting is recommended.
East Alpine ecotype
HARVEST AND YIELDS
Resistance to lodging: intermediate.
Shattering tendency: low.
Ripeness: the spike changes colour to grey-brown and appears to dry up. The ripeness of the seeds is determined by the nail test. Culms and leaves are still green at this point.
Ripening period: at the end of July.
Harvesting technique: direct threshing is recommended. Because of leaf mass, there may be a proportionate amount of threshing to contend with (4-6 tonnes/ha). Seeds have sufficient seed flow and can be cleaned easily.
Crop yields: yields depend greatly on the cultivator’s experience and range between 200 and 600 kg/ha.
Optimal maintenance allows two to three harvesting years.
