Plant pathogens are traditionally controlled using pesticides, but a more sustainable approach is to make use of the plant’s own defence mechanisms. Bio-stimulants are substances that boost the plant immune system and thereby prevent the spread and severity of diseases. The natural element silicon (Si) is such a biostimulant. Silicon is not essential for plant nutrition, but a wide range of beneficial effects of silicon has been reported when plants are exposed to abiotic stress situations (heat, drought, salt, etc.) or biotic stress situations (bacteria, fungi, insects, etc.).



One of these beneficial effects is thought to be caused by anatomical changes in plant tissues due to silica deposition in cell walls (biomineralisation to form phytoliths)

Silicon-containing products are commercially available, but only the small soluble, non-polymerised fraction of these mixtures is bio-available for plants. Intrahorti has now invented a method to formulate an exceptional high concentration of bio-available orthosilicic acid (Intra Eco Shield). The toxic effect on plant growth (phytotoxicity) of this innovative formulation was evaluated on an active (cucumber) and a passive (tomato) silicon accumulator, and its efficacy against powdery mildew infection was assessed in cucumbers.

Test set-up and evaluation

Tomato (Solanum lycoprsicum) and cucumber (Cucumis sativus) plants were grown in gutters with drippers on rockwool slabs under LED lights 18 h on/6 h off, mimicking commercial greenhouse conditions. Water pH was maintained between 5.5 and 6.5 and standard commercial plant nutrients were added. Phytotoxicity test: Two gutters with tomato plants and two gutters with cucumber plants were used to assess the phytotoxicity of the formulation. For each species, one gutter received one day per week application of 1,000 ppm Intra Eco Shield for the duration of 43 days. The other gutter received water treatment and served as control group.

No phytotoxicity observed

The application of 1,000 ppm Intra Eco Shield at 1 day per week for the duration of 43 days did not result in any statistical differences in height between treatment and control for both tomatoes and cucumbers. The plant condition score remained very close to 1 indicating no negative effect of Intra Eco Shield treatment on plant health.

The cucumber fruit yield at the end of the phytotoxicity test period is provided in Table 1. The differences in weight and density were not significant between the two groups, the increase in volume for the test group was statistically significant. This implicates that the high dose Intra Eco Shield application did not have any negative effect on the cucumbers, and even may have been positive on the fruit yield.

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