**Session IV -- Physiology, Ecology and Production -- Poster IV-6**

**Environment and Herbicides Effects on the Quantity of Covered Grains
in Naked Oat**

Lanoie, N.^1^, Collin, J. ^1^, Frégeau-Reid, J. ^2^, Pageau, D. ^3^,
Lajeunesse, J. ^3^, Durand, J. ^4^, Vanasse, A. ^1\*^.

^1^Department of phytology, Laval University, Quebec, QC, Canada;
^2^Agriculture and Agri-Food Canada (AAFC), Ottawa ON, Canada;
^3^AAFC-Normandin, QB, Canada; ^4^Semican inc., Princeville, QC, Canada.

\*Corresponding author: Phone: (418) 656-2131 #12262; E-mail:
<anne.vanasse@fsaa.ulaval.ca>

With hulless grains and higher nutritional value, naked oat (*Avena
sativa* L. *var nuda*) can be used as feed for animals, as food for
human consumption, and introduced in pharmaceutical and cosmetic
products. Because of its high energy value, naked oat is an interesting
feed for racing horses. Unfortunately, the naked grain character
expression is rarely complete. Naked oat harvested in the province of
Quebec, Canada, has on average 10 % of covered grains and sometimes
more. The objective of this study was to evaluate the effect of
environment, herbicides and their application stage on the quantity of
covered grains in naked oat. Eight oat lines known to express genetic
variability for naked grain characteristics were selected. Three of them
produced few covered grains, three lines gave a lot and the two others
average between those two groups. The naked oat lines were evaluated
over two years at four experimental sites in the province of Quebec,
Canada. At each site, each entry was treated with one of three types of
herbicides: Bromoxynil/MCPA, Dicamba/MCPA and Thifensulfuron
methyl/Tribenuron methyl and compared with a hand weeded check. The
herbicides were applied at the same growth stage (12-13 of Zadoks). In
another trial, at two experimental sites, herbicides were applied on
three lines at two growing stages: Zadoks 12-13 and 22-23. The results
showed that the proportion of covered grains differed among years,
sites, herbicides and lines. In the first trial, in 2006, the site with
the greatest proportion of covered grains had 5.7 % of covered grains
(by weight) and 2.2 % more than the other sites. In 2007, a different
site had the greatest proportion with 7.1 % and 2.5 % more covered
grains than the other sites. Furthermore, Dicamba/MCPA applications gave
5.5 % and 6.7 % of covered grains in 2006 and 2007, respectively. It was
1.9 % and 1.7 % more covered grains compared to the other treatments.
The line with the lowest covered grains quantity had 1.0 % while the
highest had 9.3 %. Lines that developed the fewest covered grains
produced 5.6 % in 2006 and 5.8 % in 2007 less covered grains on average
than the lines that produced a lot of covered grains. With the
Dicamba/MCPA application, the lines that produced a lot of covered
grains gave 7.9 % in 2006 and 6.8 % in 2007 more covered grains than the
lines that produced few covered grains. There were no significant
differences among the remaining herbicide treatments and the weeded
check for the proportion of covered grains. In the second trial,
Dicamba/MCPA application at the 22-23 Zadoks stage raised the quantity
of covered grains by 3.9 % in 2006 and 5.0 % in 2007 compared with
application at the earlier stage. For Bromoxynil/MCPA and Thifensulfuron
methyl/Tribenuron methyl, no differences were noticed among the 12-13
and 22-23 Zadoks stages applications in the quantity of covered grains.
One line reacted very strongly to the late Dicamba/MCPA application. It
gave up to 19.0 % of covered grains, 10.0 % more than the early
application. These results demonstrated that we can reduce the
proportion of covered grains by growing oat varieties with the least
tendency to retain hull and by avoiding herbicides with phytotoxic
effects such as Dicamba/MCPA. Since Dicamba/MCPA has an impact on the
phenotypic expression of the grains, it would be interesting to evaluate
if it has an influence on the nutritional value of naked oat.