The benefits of shade

I'm rethinking a bit why the basil sown thickly in a flat near the potting bench is still relatively succulent compared to its brethren in adjoining pots and in the ground. I thought it was the benefits of fluffy potting mix, and richer fertilization, but now I'm thinking it's extremely useful that the flat is in filtered morning and afternoon shade.

I've always thought of basil as a warmth-loving plant (which it is), but maybe the blastingly hot afternoon sun here simply shuts down leaf growth, closing stomata and depressing photosynthesis, and therefore leaf expansion. The plants I transplanted to a container (from the flat) that receive more afternoon sun are looking more and more stressed as the heat wave continues, whereas a single plant in soil that's shaded by beans and in a spot that gets full afternoon sun looks quite nice. Perhaps I'll need to do an experiment! And more investigation about how basil flavors develop, etc., would also be interesting.

Certainly the combination of extreme heat and 10 hours of full sun isn't ideal for many vegetables - here in the South, both plants and the gardener are looking for a respite.