NO - Besoin d'assistance

Composition of tomatoes and tomato products in antioxidants (WG1) page 55
__________________________________________________________________________________________
temperature, light, water availability, fertilizer resources (except nitrogen) and variety.
Another question is what could also be the influence of plant growth and development
regulators on phenolic concentration since there could exist important interactions : some
phenolics (chlorogenic acid and rutin) have been suggested as regulants of auxin (like indole-
3-acetic acid) metabolism (Buta and Spaulding, 1997).
6.5. Conclusions on the influence of cultural practices and agronomic aspects
Many studies and results are old and can hardly apply to the current cultivars used
now in processing tomato cropping. Recent studies apply to cultivars poorly known and not
utilized in the European area. Moreover, in many cases the experiment conditions (e.g. soil
characteristics) were not precisely detailed and it is difficult to consider the results as general
enough.
The contents in antioxidants were generally calculated relative to the fresh matter and
the papers rarely give indications about the fruit dry matter content or the juice solids content.
However it should be more accurate and more reliable to express the antioxidant
concentrations relative to the dry matter in order to really understand the influence of the main
involved factors because these factors often modify also the dry matter content of tomato
fruit.
Some factors seem antagonist with regard to the development of different antioxidants.
For example, water shortage during cropping could be favourable to tomato fruit vitamin C
content and possibly unfavourable to tomato fruit lycopene content. It seems that direct
sunlight is favourable to vitamin C and phenols accumulation in fruit while lycopene would
develop better in fruit protected by crop foliage. Few data have been found about the
influence of some cultural factors, for example nitrogen and phosphorus/lycopene,
water/lycopene, temperature, phosphorus and potassium/vitamin C, temperature, water and P-
K nutrition/phenols, temperature, light, water and mineral nutrition/vitamin E.
It is important to get a good understanding of the influence of water availability on
antioxidant accumulation in tomato fruit because water is a major agronomic factor of great
influence on the quantitative and qualitative characteristics of processing tomato production.
Maybe fertilization could not be the most efficient way to influence the level of antioxydants.
It is surely more difficult to explore the influence of fertilizers. Knowledge of soil nutrient
availability by soil analysis after chemical extractions remains unsufficient because it gives an