Biomedical Engineering Reference
In-Depth Information
Seed Production
Intermediate wheatgrass spikes are borne on erect stalks, and seeds are easily
threshed [
95
]. Because of its relatively high yield of large seed and vegetative
characteristics, it has been proposed as a possible perennial grain crop in a
low-impact sustainable agricultural system [
96
]. For optimum seed production,
row spacing of 60 cm under irrigation and 90 cm under dryland conditions are
recommended at a seeding rate of 9.2 kg ha
1
(irrigated) and 6.9 kg ha
1
(dryland).
Seed fields should be planted in late summer by mid-August with adequate soil
moisture or supplemental irrigation or early in the spring. If fall moisture and/or
spring moisture is not reliable, then a fall-dormant seeding just prior to the soil
freezing is recommended. Under irrigation, seed yield will range from 728 to
1,176 kg ha
1
averaging 952 kg ha
1
. When grown as a dryland crop, seed yields
average 392 kg ha
1
and range from 224 to 560 kg ha
1
. Seed production fields
remain productive between 5 and 10 years [
97
].
Tall Wheatgrass
Taxonomy and Domestication
Tall wheatgrass [
Thinopyrum ponticum
(Podp.) Liu and Wang] was previously
treated as
Agropyron elongatum
(Host) Beauv.,
A. elongatum
ssp.
ruthenicum
Beldie in North America, and as
Elytrigia pontica
(Podp.) Holub by Asian botanists
[
35
]. The true
A. elongatum
, now excluded from
Agropyron
sensu stricta, is a
diploid (2
n
14), while the robust grass known as tall wheatgrass in North America
is a decaploid (2
n
¼
70) [
35
].
Tall wheatgrass is indigenous to southern Europe and Asia Minor and was
originally introduced into North America from Turkey in 1909 [
98
]. In its native
habitat, it is often associated with saline or alkaline soils in meadows, salt marshes,
and seashores [
99
]. It is a long-lived, coarse, vigorous, perennial bunchgrass with
leaves that are long and erect. It is the latest maturing of the grasses adapted to the
temperate rangelands of the west.
¼
Areas of Adaptation and Production
Tall wheatgrass is one of the most saline or alkali-tolerant cultivated grasses and is
particularly noted for its capacity to produce forage and persist in areas that are to
alkaline or saline for other productive crops. On less favorable sites, e.g., saline and
low moisture, it is short-lived unless there is a water table below the dry surface.
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