Agriculture Reference
In-Depth Information
Fig. 3.2
USDA plant hardiness zones for 48 contiguous states in the USA (
http://planthardiness.
of commercially available switchgrass cultivars
[
14
,
24
], but some southern cultivars are not well adapted to colder climates. In
related research, several long-term studies found that switchgrass cultivars should
not be moved more than one USDA hardiness zone north of their origin [
11
,
12
,
21
,
25
], and Casler et al. [
11
,
12
] also wrote that moving north or south from a switch-
grass' origin (latitudinal movement) is much more critical than moving switchgrass
between east and west.
When considering a cultivar for planting, producers should keep in mind the dif-
ferences between lowland and upland switchgrass; upland ecotypes originate from
Mexico to Canada and are more cold-tolerant and sod-forming, while lowland eco-
types originate from Mexico to Nebraska and are higher-yielding and bunch-
forming grasses [
25
]. Lowland varieties tend to have better disease and drought
resistance [
22
] and usually have greater yields due to tall, thick stems, two key
characteristics of biomass productivity [
25
]. Moving a lowland cultivar that origi-
nates in southern regions to northern regions can immediately boost yields, as long
as that cultivar has the winter hardiness to survive in colder climates [
21
].
The cultivars listed in the Fig.
3.2
are publicly available and have been developed
for either forage production or conservation. With recent interest in cellulosic bio-
energy, both public and private institutions are developing new cultivars that pro-
vide high biomass and energy yields such as the lowland types “EG 1102,”
“Performer,” and “Cimarron” and “EG 2101,” an upland type [
26
].
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