Abstract:
Insect damage in canola
adversely affects its productivity and
quality and is considered one of the most
important degrading factors in Egypt. The
effect of foliar application of salicylic
acid (SA) on aphid populations, growth
and yield of canola (Brassica napus, L.)
cv. serw 4 was the major goal of this
study. Two experiments were conducted
at the farm of Faculty of Agriculture,
Suez Canal University, Ismailia, Egypt,
during 2014 and 2015 seasons, to achieve
this target. Each experiment included four
levels of SA (0, 50, 100, 200 mg l-1). The
experimental results revealed that SA, at
low concentration (50 mg l-1), was an
effective treatment for reduction the
number of aphid populations and colony
depth on the main inflorescence,
contributed with reducing the thickness of
secretory tissue of flower pedicel. The
level of 50 mg l-1 of SA-treated canola
had the highest number of stomata cm-2,
along with the lowest width of both stoma
and its aperture. Thickness of xylem
tissue and the number of xylem vessels
bundle-1 in leaf midrib, reducing sugars
and free amino acids was increased at
50 mg l-1 SA, but free phenolics content
did not affected significantly. Under
controlled conditions, changes in
temperature of infected leaves allowed the
discrimination between healthy and
infected areas in thermo-image, even
before visible symptoms of aphid
infestation appeared. The detection of
modifications in plants or canopies,
associated with low insect severity in the
early stages of infestation, was crucial for
the targeted, site-specific or on demand
application of integrated aphid control.
Canola, which was treated with 50 mg l-1
of SA, gave 30.5 and 27.9 kg of oil ha-1
over the control. It was concluded that spraying of SA at 50 mg l-1 was an
effective elicitor to diminish the aphid
numbers on canola inflorescence and
improve its yield.
