He regado con 100ml la maceta de 1L para plantar,e...

Frequency and small amounts is key at this stage. As long as the seedling isnt wilting and too dry then keep doing your thing although bear in mind roots seek out water so in my opinion it is better to water some distance away from the stem to encourage root development - I do that with all my veg / outdoor seedlings too. At this stage just try to give it a nice sprinkle and then if it is dry 24 hrs later give it another. If you are keeping temps and humidity good, plant leaves and not roots do all the work at this stage. When you have 2 sets of full true leaves it is time to increase amounts (and probably think about transplanting to a bigger container, 1L is quite small).