INFLUENCE OF THE TYPE OF SOILS ON PHENOLIC COMPOUNDS OF THE NUTS AND CROP LOSSES
Numerous field observations have shown that the nature of the soils seems to play a great role in crop losses. Very often in spite of repeated copper treatments crop losses are very high in shallow permeable, acid soils.
Two types of works have been carried out for 4 years :
- basic research : these ones aimed to find out which soil factors may influence phenolic compounds amount in husk tissues and describe and explain soil effects through polyphenolic compounds variations,
- trials in fields: we compare several treatments :
- placement of organic matter,
- calcic dressing,
- foliar treatments : Cu, antibiotic, Ca, Zn, Cu + Fe,…
Not any treatment is able to reduce alone significantly the losses of crop. Cu treatments must be realized but not more than 4 or 5 each year. In fact, the solutions of the problem will be resolve by several practices: Cu sprays, well balanced dressing, maybe Cu + Fe.
We are going to study some growth regulators, and fertilizers applications in September to modify the nutrient accumulation in stem and bark of the walnuts.