Abstract:
Grafting of
Cucurbitaceae
species to some rootstocks seems to be especially
beneficial
for the nitrogen nutrition of these plants. Moreove
r, melons (
Cucumis melo
L.) have been
considered among those plants that could benefit fr
om the addition of Silicon (Si) in the
Nutrient Solution (NS). Thus, two experiments were
carried out in the following order: (i)
it was investigated how grafting affects nitrate ab
sorption (following the disappearance of
nitrates from NS), leaf water relations, leaf gas e
xchange, chlorophyll parameters and
antioxidant activity, and (ii) it was also assayed
which of the aforementioned physiological
factors could be associated with Si supply in melon
plants at early developmental stage
when metabolism is intense. Results revealed that g
rafting and Si supply could improve
photosynthesis, nitrate absorption, and biomass pro
duction in melon plants with respect
to non-grafted or plants not receiving extra Si. Gr
afting melon on Cucurbita rootstock
improved photosynthetic performance associated with
higher antioxidant activity in
melon leaves. Silicon supplementation results lend
support to an active role of Si in
biochemical processes at chloroplast level in melon
s. Increased assimilation rates in
grafted and Si treated plants (20 to 35%), resulted
in higher nitrate depletion from the
medium (17 to 18%), which boosted shoot biomass pro
duction (23 to 26%) compared to
the control plants. Our results suggest that grafti
ng and Si supply in melon plants may
lead to a better crop performance and a lower envir
onmental impact of greenhouse
fertigation effluents with respect to nitrate leach
ing, in some instances.
Keywords
: Antioxidant activity, Biomass production, Gas exc
hange, Hydroponic melons.
