Native Grasses for Biomass Production at High Elevations - Industrial Crops: Breeding for BioEnergy and Bioproducts - page 109

(pubescent wheatgrass), and A. pulcherrimum Grossh. Barkworth et al. [ 63 ]recognize
two subspecies within intermediate wheatgrass subsp. intermedium , which is glabrous
and subsp. barbulatum (Schur) Barkworth and D. R. Dewey, which is pubescent (syn.
pubescent wheatgrass). Intermediate wheatgrass was first described from a collection
in Yugoslavia in 1805 as Triticum intermedium by Host [ 64 ]. Intermediate wheatgrass
spikes are borne on erect stalks and seeds are easily threshed, lending itself as a
possible perennial grain crop on hilly or otherwise marginal land, thus reducing the
farmers economic costs (i.e., labor and fuel) along with soil erosion (i.e., low-impact
sustainable agriculture) [ 65 ]. Intermediate wheatgrass is tolerant of some saline soils,
used as a fall and early winter forage [ 66 ], as well as providing an immense genetic
reservoir to select from for disease and insect resistance in the cereals [ 67 ]. Interme-
diate wheatgrass is generally considered to be highly self-sterile, although self-fertile
plants occasionally occur [ 9 ]. The first introduction (PI 20639) came into the USA
from Trans Ural, Siberia, in 1907 [ 68 ].
Areas of Adaptation and Production
Intermediate wheatgrasses' natural distribution is found in steppes, on open stony
and aleurite slopes among shrubs up to the lower mountain belts of southern Europe
through the Middle East and southern USSR to western Pakistan [ 64 , 69 ]. Dewey
[ 68 ] reported that no intermediate wheatgrass collections have been recorded south
of 30 north lat. and the more southerly collections were made only at higher
elevations. Most collections within Iran were between 1,200 and 2,100 m.
In North America, intermediate wheatgrass is used for hay and pasture on sites
receiving at least 35-cm annual precipitation at altitudes up to 3,000 m. It is widely
distributed in the Intermountain Region and northern Great Plains of the USA and
Canada where it grows best on well-drained, fertile soils that receive 30-46 cm of
annual precipitation. It is recommended for sagebrush sites and high mountain areas
up to 2,700 m. It is moderately tolerant of shade and alkalinity. As a general rule,
intermediate wheatgrass is adapted to sites currently occupied by smooth brome-
grass ( Bromus inermis Leyss.). Yields and stand persistence can be increased in
intermediate wheatgrass if grown with a legume. In drier areas (less than 38 cm of
precipitation), intermediate wheatgrass yields more than smooth brome and crested
wheatgrass [ Agropyron desertorum (Fisch. ex Link) Schult]; however, after several
years of harvesting, intermediate wheatgrass yields decline. The pubescent form is
considered to be better adapted to the more southern limits of the species adaptive
range in Asia [ 70 ] and the USA [ 71 ]. It appears to be better suited to droughty,
infertile soils and saline sites that receive 30-35 cm of annual precipitation than
typical intermediate wheatgrass [ 66 ].
Intermediate wheatgrass will outyield bromegrass and reed canary grass when
grown on fertile well-drained irrigated land and will equal crested wheatgrass and
outyield bromegrass under drought conditions on dryland. Under favorable condi-
tions, intermediate wheatgrass will outyield both crested and bromegrass under