container size for vegetable plants

as i mentioned before, i plan to go to all containers next season.
i went on the internet and just typed in "container size for vegetable plants"
what i found was confusing.

i printed three reports
one from nc state university, one from virginia cooperative extension and one from iowa state university

for instance iowa state university has this
beets 2 gallon 2 to 3 inches apart
eggplant 2 gal 1 plant
tomatoes standard 3 gal 1 plant

virginia cooperative has
beets 1/2 gal 2 to 3 plants
eggplants 5 gal 1 plant
tomatyoes standard 5 gal one plant

nc state
beets 5 gal window box
eggplants 5 gal pot
tomatoes 5 gal pot

all 3 offer the same growing tips etc. but the container size is different for all three.
the virginia cooperative says that most plants need containers 6 to 8 inches deep.

since i have many 2 gal containers which i wasn't going to use maybe i will try them out on some things like beans, peas and zucchini.

has anyone ever grown these three in 2 gal containers and if so, do you recommend bush or vine type?

thanks

Herbie,
My father-in-law used 5 gallon buckets (like paint buckets) filled with mulch to grow his tomatoes and cucumbers. No soil at all. Poked a hole in the bucket about halfway down. Watered the mulch with Miracle Grow, and that was it! The water would only go as high as the hole, so the mulch stayed damp, but not wet. He'd put the buckets in full sun along a chain link fence (for staking)
He had the best veggies in town! The rootballs on those plants were amazing!
MerryMary

what do you mean "filled with mulch".

He just opened a bag of pinebark or cypress mulch, preferably cypress, and filled the bucket. He'd make a hole in the center, stick the tomato plant in, and shuffle a little mulch around it to anchor it again. Then watered the mulch heavily with Miracle Grow water. The roots loved growing in the damp mulch, and were always massive fiber balls by the end of the season. Remember, tomatoes are actually vines. Cucumbers he planted from seed, about an inch down, under the mulch.

you learn something new every day. maybe i will give it a try in one or two buckets. thanks