INCIDENCE DU PELLICULAGE DES SEMENCES SUR L'IMPLANTATION D'UNE CULTURE DE CAROTTES
Under controlled conditions, and regardless of the temperatures studied, no change was observed in the percentage of germination as a result of coating or the associated agents (fungicides such as iprodione, metalaxyl and captan, or oxygen sources [calcium peroxide]). The rate of germination showed significant variation, especially at low temperature (10°C) during the first days.
In the field, coating itself did not alter the emergence characteristics for any of the years studied. Coating using various combinations of an active ingredient and calcium peroxide had varying effects depending on the year. In 1989, metalaxyl had a significantly depressive effect on the final population. The active ingredients tested in 1990 (including metalaxyl, at a lower dose) had no significant effect on final population (either in natural conditions or using a rain simulator), although significant differences were observed.
Seeds coated with iprodione, thiram and metalaxyl differed from the uncoated, untreated control sample: coated seeds showed a lower population (under 1990 crusting conditions) or a delay during the early days of emergence (under natural conditions in 1990 and 1991).
The combination with calcium peroxide caused a sharp improvement in 1989, but was onyl a trend in 1990 and 1991: under these experimental conditions, this additional source of oxygen for the seeds either was not necessary, or could not be fully utilized.
Moreover, the results of these experimental studies demonstrate that using active