Slightly different but I grow my watermelons and lopes between my grape rows and it works out well.

Cantaloupes wildly spreading under my fig trees. Doing great!

I have squash and tomatoes in a raised bed around one of my younger fig trees. They're all about the same size now...between two and three feet tall. No problems here.

I would personally plant the rows with a good cover crop compiled of nitrogen fixers and nutrient accumulators.

The best Nitro fixer is white clover, since it stays low. It also attracts beneficial insects. Legumes are nitrogen fixers, so peas and beans of all kinds would work quite well, especially if you multch the dead plant for the winter.

Nutrient acculumators have long deep rots which reach down deep into the soil, and pump up nutrients. All plants do this, but some better then others. Comfrey (make sure its the sterile "blocking 4" type), or yarrow are the best that ive read about, and native to north america (yarrow). Fennel does this well too (perennial types). You coudl also throw in some lupine, which is mostly a nitrogen fixer, but also has deep roots that pump up some nutrients.

Here is a good page from the Ontario gov, if you like credible sources of info :D

http://www.omafra.gov.on.ca/english/crops/facts/cover_crops01/choosing.htm

One would assume without supplimental fertilizer/companion plants the veggie garden will compete for nutrients with the trees, unless you do a lot of cover crops, interplanting and compost/manure addition. In other words, if you can keep the soil bursting with fertility, you should have no problem.

You may be interested in "forest gardening" as well.... which is essentialy what you speak of..

Potatoes seem to do very well for me in semi-shade under semi-dwarf fruit trees. Other things I grow under/between mine include leeks, rhubarb, garlic, squash, greens.

And I thought one was supposed to keep the area under our fruit trees weeded and mulched for summer. I would love to see photographs of these plantings. They sound beautiful. Mrs. G

Melons and winter squash qualify as mulch, and shelling peas and shelling beans qualify as nitrogen fixers. I doubt I will grow potatoes past the second year, but they, too, can mulch a wide area. In fact I left one particularly wide lane in the middle, for potatoes and sweet potatoes, after the trees have grown. The rest (turnips, beets, onion, garlic, asparagus on the perimeter) is just for more storage veggies. I suppose I could plant a few jalapeno, also for freezing. No carrots or parsnips, the soil is too hard.

I guess one would have to be careful with N, when the orchard is mature, not to affect the fruit quality. Likewise, no celery or cardoon, to avoid too wet soil.