Is it possible? I want to long seed torrents, i dont want to use my bandwidth now, when there are lots of other seeds.

Go to "Settings -> Transfers -> General" and tick both "Auto-manage slots" (or just the "Uploads" one if that's really all you need).

If you want to configure how it works in more detail, you can click the appropriately named "Details" button to edit or create rules on how Tixati handles your torrents and slots. For instance, what you asked for is right there in the first lines ("Seed transfers that are in greatest need, with few seeds and more peers").

Hope this helps, cheers.

right click any selected torrent you want to set and go to seeding->remote seed limit

Along with above option i.e. remote seed. (which will stop seed once the remote seeds reaches above specified count).
I guess you want to start again when the remote seed goes low / less.

In scheduler there is option "Start all Transfers" there which will re-evaluate the remote seeds and if found below specified number will start seeding again. you can schedule such chains daily/weekly/monthly etc.

Disclosure:
I have not done such setting my self. but the way developers have given that options that should work.