this article points to tests that show foliar spraying is quite effective but as a root application not so much.
this is the same as my earlier research. Also i dont think it affected your seedlings like you say. I think that was just a lot of light and fast growth. It didnt make a final difference of 3% in harvested tomato plants when used at the roots. You would never see that growth.
Also interesting is that tria can make the plant vulnerable to insect infestations and should not be given to an insect infested plant either
Lots of credits shown for this article.
manicbotanix.com