Abstract:
We evaluated the effect of different concentrations
of Phosphite (Phi) (0, 0.25, and 0.50
mM) in nutrient solution on lettuce and chard. The
fresh and dry biomass of lettuce
shoots and heads, root volume, and P accumulation i
n roots showed no significant
differences compared to the controls for different
Phi concentrations in nutrient solution.
In chard, no statistical differences were found amo
ng Phi concentrations for P
concentrations in roots and shoots, total free amin
o-acids in leaves, chlorophyll-b, and
soluble sugars. The phosphorus concentration in let
tuce shoots was 15.6 and 50.6% higher
in plants treated with 0.25 and 0.50 mM of Phi, res
pectively, compared with the controls.
In lettuce, phosphorus levels in roots, total free
amino-acids and soluble sugars in leaves
were statistically greater for 0.25 mM of Phi in nu
trient solution. The concentration of
chlorophyll-a, b and total chlorophyll in lettuce l
eaves increased positively with Phi
concentration in nutrient solution. The addition of
more than 0.25 mM of Phi to the
nutrient solution for chard negatively affected the
fresh and dry biomass weight of shoots
and roots, and P accumulation in roots and shoots.
The concentration of chlorophyll-a, b
and total chlorophyll in chard leaves was statistic
ally higher with 0.25 mM of Phi in
nutrient solution. We conclude that Phi has differe
ntial effects on lettuce and chard
physiology, and positive plant responses may be obs
erved when Phi is used up to 0.25 mM
in sufficient P conditions.
Keywords:
Biomass weight, Chlorophyll, Phosphorus, Total fre
e amino-acids, Total soluble
proteins.
