Page 58 - Volume 1, Issue 2, July 2008

Travlos et al. 110
Science Department at the Benaki Phy-
topathological Institute. These characters
can provide a safe recognition of the spe-
cies. In actual measurements of spikelets
in the field the mean length of the awns,
for example, was 5.514 cm for A. sterilis
and 3.625 cm for A. fatua. Also, the mean
length of the florets was 2.392 and 1.85
cm for A. sterilis and A. fatua, respective-
ly. Moreover, a difference was observed in
the time of maturation, A. fatua maturing
about 10-15 days later than A. sterilis, and
this is likely associated with different tem-
perature requirements for germination;
optimum germination temperatures for A.
sterilis are reported to be lower than those
for A. fatua (6, 17).
It is worthy to mention that the above
characters can provide a safe recognition
of the species if used on the seeds as they
are shedding. However, processing of the
seeds after shedding, which may cause
breaking of awns, rubbing off the hairs,
breaking of florets or bases etc. is expect-
ed to reduce the diagnostic value of these
characters.
The wild oat accessions from the Viotia
region, when grown under the same con-
ditions in pots in the greenhouse, exhibit-
ed a significant variation in growth habit
and other parameters of seedling devel-
opment (Table 3). Variability was wide in
the A. sterilis accessions but very limited in
the A. fatua accessions.
The most important variation found
was related to the growth habit of the A.
sterilis accessions, in some of which the
seedlings had an erect growth pattern, in
some others a semi-erect pattern and in
others a prostrate growth pattern (Figure
2). In all A. fatua accessions from Viotia the
seedlings exhibited only the erect growth
habit. The peculiar prostrate pattern of
growth for some A. sterilis accessions has
also been observed by other researchers
in Greece (3) as well as in other countries
(12, 16).
Significant differences among wild
oat accessions were also observed when
plant height and tillering were compared
(Table 3). Tillering, measured as the num-
ber of tillers per plant, seems to correlate
negatively with plant height and posi-
tively with the growth habit, being high-
er in plants of semi-erect and highest in
plants of the prostrate growth pattern, in
the A. sterilis accessions. In the A. fatua ac-
cessions, in which only the erect growth
pattern was observed, tillering was mini-
Figure 2. Growth habit of A. sterilis accessions from the Vi-
otia region in Greece. Erect (A), Semi-erect (B) and Prostrate
(C) seedling growth pattern .
Table 2. Mature seed characters discriminating A. fatua from A. sterilis in the field.
Character Avena sterilis Avena fatua
Maturity Earlier maturing Later maturing
Awn length (cm) 3-7 3-4
Awn attachment Below middle of floret Above middle of floret
Floret length (cm) 1.7-3.0 1.4-2.1
Basal scar shape Large, elongated Absent or small round
Hair covering 50-80% of floret surface 30-60% of floret surface