Soil-less cultivation of horticultural crops represents a fairly recent innovation to traditional agriculture
which has several advantages including higher water-use efficiency. When plants are grown with this
system, their roots come in contact with nutrients solely via the hydroponic solution. Although its
beneficial effects have been widely demonstrated, silicon (Si) is mostly omitted from the composition of
nutrient solutions. Therefore, the objective of this study was to assess the beneficial effect of Si addition
to hydroponic solution on quali-quantitative aspects of edible production of two cultivars of corn salad
(Valerianella locusta (L.) Laterr.) grown in soil-less floating system. Impacts on shelf life of this food were
also studied.
Results show that the supply of Si increased the edible yield and the quality level reducing the nitrate
concentration in edible tissues. This result might be attributed to changes either in the metabolism (such
as the nitrate assimilation process) or to the functionality of root mechanisms involved in the nutrient
acquisition from the outer medium. In fact, our results show for the first time the ability of Si to modulate
the root activity of nitrate and Fe uptake through, at least in part, a regulation of gene expression levels of
the proteins involved in this phenomenon. In addition, the presence of Si decreased the levels of polyphenoloxidase
gene expression at harvest and, in post-harvest, slowed down the chlorophyll degradation
delaying leaf senescence and thus prolonging the shelf life of these edible tissues.
In conclusion, data showed that the addition of Si to the nutrient solution can be a useful tool for
improving quali-quantitatively the yield of baby leaf vegetable corn salad as well as its shelf life. Since the
amelioration due to the Si has been achieved only with one cultivar, the recommendation of its inclusion
in the nutrient solution does not exclude the identification of cultivars suitable for this cultivation system
and the comprehension of agronomical and environmental factors which could limit the Si benefits
