ICARDA annual report 2004

ICARDA Annual Report 2004
54
spontaneum) accessions selected
from ICARDA’s genebank using
agroclimatological information generated
by GIS.
Accessions were grown in a
plastic house under three replicated
day-length and temperature treatments.
The earliness response was
assessed in a long-day treatment
using vernalized germinated seeds.
Photoperiod sensitivity was estimated
in a short-day treatment
with vernalized seeds, while vernalization
sensitivity was studied
in a long-day treatment using
unvernalized seeds. The number of
days to heading in each treatment
was recorded and subjected to multivariate
statistical analyses.
Hierarchical cluster analysis produced
thirty photothermal response
groups, which were then used in a
discriminant analysis. The first and
second canonical discriminant functions
obtained (Fig. 22) accounted
for 55.2% and 33.6% of the total
variation in the experiment, respectively.
The first function was strongly
linked to the vernalization
response and, to a lesser extent, to
the earliness response; the second
function was closely associated with
the photoperiod response.
Most accessions exhibited a
weak vernalization and photoperiod
response (lower left quadrant of
Fig. 22). A few accessions exhibited
weak vernalization and strong photoperiod
reactions (upper left quadrant).
The remaining accessions
required strong vernalization
(right-hand side of Fig. 22) and, in
some cases, were photoperiodinsensitive
(lower right quadrant).
The 10 accessions with the
weakest earliness response were
landraces from Egypt, Iran,
Lebanon, Libya, and Oman, and
the improved germplasm
Mari/Aths and ‘Harmal.’ The 10
Fig. 22. Results of a canonical discriminant multivariate statistical analysis conducted
using data on number of days to heading in 227 barley accessions (circles). Thirty
photothermal response groups are indicated by different colors and group centroids
are represented by solid squares. ‘Discriminant Function 1’ was strongly linked to vernalization
sensitivity and, less strongly, to earliness per se. ‘Function 2’ was linked to
the response to photoperiod regimes.
accessions with the weakest vernalization
response included a landrace
from Afghanistan and nine
improved varieties and lines, six of
which were bred by ICARDA. Most
sensitive to vernalization were
ICARDA’s ‘Pamir 9’ and ‘Batal-1,’ a
landrace from Tunisia, and landrace
and wild barley accessions
from Azerbaijan and Turkmenistan.
Among the 10 least photoperiod-sensitive
accessions were landraces
from Ethiopia, Morocco,
Pakistan, and Yemen, two wild barley
accessions from Jordan,
ICARDA’s H. spontaneum 41-1 line,
and ICARDA’s improved barley
SLB05-96/H. spont.41-5. The 10
most photoperiod-sensitive were
landraces from Azerbaijan, Iran,
Jordan, Syria, Tunisia, Uzbekistan,
and the ‘Tokak’ cultivar from
Turkey.
Different genetic mechanisms
control earliness per se, vernalization,
and photoperiod response.
Therefore, the large amount of variation
identified for these parameters
in the accessions tested will be
useful in programs designed to
breed material suited to different
temperature scenarios. Earliness per
se and vernalization are related to
temperature, and so will respond
directly to warmer climates.
Although photoperiod response
will not be affected by climate
change, the genetic variation in this
trait could usefully be exploited in
efforts to adjust plant phenology to
new climatic conditions.