of a prophylactic treatment with potassium silicate to control
strawberry diseases and to increase strawberry nutraceutic value
main objective of this project is to verify whether treatment with
potassium silicate can induce the accumulation of phenolic
products and flavonoids in the leaves and fruit of strawberry
plants. To test this hypothesis, plots of conventional and
day-neutral strawberries will be planted in the spring of 2004 and
kept in place until fall 2005. Foliar treatments with potassium
silicate will begin in the spring of 2004, with the appearance of
the first leaves, and continue at varying frequencies and
durations depending on the cultivar. The varieties used will be
Yamaska, L'Acadie, Kent, Orleans, St-Jean Orleans and St-Laurent
Orleans in the case of conventional strawberry plants, and
Seascape and Aromas in the case of day-neutral strawberry plants.
Four distinct treatments per cultivar will be applied: Control; 8
mM Si + 16 mM K; 16 mM Si + 0 mM K; and 0 mM Si + 32 mM K. A split
plot design will be used, with 10 plants per experimental unit.
The data collected will be divided into three different categories.
Initially, the effects of the silica will be evaluated
on growth and yield by measuring the wet and dry weight of the
leaves, petioles, crowns and roots. In this same category, the
photosynthetic activity will be measured three times during the
vegetation period with a LI-COR 6400 infrared spectrophotometer.
Then, the effect of the silica on disease will be evaluated.
Initially, symptoms of diseases such as powdery mildew,
anthracnose and gray mold will be evaluated, if they develop in
the field, by assessing the incidence of disease expression vs.
treatment. Then, the development time of gray mold caused by
Botrytis cinerea during post-harvest storage at 4 C for 14 days
will be evaluated. Finally, the silica content will be evaluated
in different parts of the plant at the end of the season. The
fruit's silica, phenolic acid, ellagic acid, flavonol, catechin,
epicatechin, proanthocyanidin and anthocyanin content will be
evaluated. According to the literature, there should be a direct
correlation between the silica content of the plant and fruit, the
quantity of phenolic products and flavonoids, and the plant's and
fruit's ability to better resist different diseases. Once
completed, this experiment will enable confirmation of whether
foliar treatments with potassium silicate can reduce the incidence
of disease in Fragaria x ananassa Duch., via the accumulation of
phenolic products and flavonoids, and also increase the
nutraceutical value of the fruit for the consumer.