Of course, everything depends on the dose.
In France colchicine is being used to treat gout in daily doses between 1 and 3 mg.
If dissolved at 0.1%( maximal concentration used for tetraploid induction) it will give between 1 and 3 ml of solution, enough to treat several dozens of seeds.

I have red an article on citrus breeding technics the last days and thereby came across the issue of polyploidity. I am now totally convinced that this is not a good thing in citrus. The growth is weaker as Ilya already wrote. But fruit quality is also much inferior. I had the image of strong and healthy polyploid plants in view as you will find in many genera. But the effect is totally different in citrus: You will louse plant quality in almost every respect.

The Japanese won't even use polyploid pt as rootstock. They believe it has an incompatability with the citrus top stock.