Hi Massimo,
welcome in the Hybrid-Forum!
Regarding your question:
When sowing hybrids, chlorotic seedlings can sometimes occur. With my asterix crossings, I didn't have the impression that they were more than with others.
A piece of advice for communication here in the forum: we started here as a purely German-speaking forum and are gradually getting used to the fact that there are also exciting hybrid breeder members who do not speak German. Understanding and answering in English is still affordable for many members from the German-speaking area - other languages tend not to. So if you want quick answers to your questions, then I recommend German or at least English as the language.