NO - Besoin d'assistance

Composition of tomatoes and tomato products in antioxidants (WG1) page 29
__________________________________________________________________________________________
Table 12. Effect of potassium addition on ripening disorders (after Winsor, 1979)
Cultivar Potassium applied (kg/ha)
404 807 1614
% unevenly ripened Moneymaker 38.9 14.9 2.1
(all forms) J 168 26.1 8.6 1.4
% unevenly ripened Moneymaker 29.5 9.2 1.9
(severe forms only) J 168 18.0 5.0 1.7
It clearly appears that K deficiency may lower the rate of carotenoid synthesis,
particularly lycopene. However, the rates of K supply applied in the study presented above
and which led to responses in ripening uniformity are very high. They should be considered as
non adapted to cultural practices, particularly in modern agriculture which is supposed to
reduce inputs, spare resources and respect environment.
Effect of Calcium
In a soil-pot culture experiment, Subbiah and Perumal (1990) tested the influence of
sources of calcium (calcium oxide, calcium chloride, calcium sulphate), concentrations (0.0%,
0.1%, 0.2% and 0.3% Ca), stages (S1 = 30th day after transplanting, S2 = 45th day after
transplanting, S3 = 60th day after transplanting), and number of sprays (S1, S2, S3, S1+S2,
S1+S3, S1+S2+S3, S2+S3) on physico-chemical properties of tomato fruits, cv. Co.3.
Moreover, all the pots received also 120 kg N/ha, 100 kg P2O5/ha and 100 kg K2O/ha. They
could significantly increase the lycopene content (from 85 to 263, 300 and 340 mg/kg fresh
matter) of the tomato fruit by calcium sprays at 0.0, 0.1, 0.2 and 0.3% Ca concentration
respectively, whatever the source of calcium. It would be interesting and necessary to verify
these results.
On the contrary, Paiva et al.(1998) cultivated tomato plants cv. Jumbo hydroponically
in a greenhouse and imposed different calcium doses in the nutrient solutions. Total carotene
and lycopene levels (expressed in fresh matter) in the tomato fruit decreased with increasing