They simply get greener because they get more light for photosynthesis. Shaded leaves won't waste resources by building a lot of chloroplasts which can't work due to low light intensity. Look at a piece of lawn under a stone, log, or alike; the grass there has no light at all, doesn't develop their chloroplasts, and hence is yellow-whitish. Plants sense not only the quantity of light but also the efficacy ('yield') of their photosynthesis machinery and adapt to the strict minimum needed; that's how biology works, never waste anything .
BTW, I have the impression the non-defoliated plants grow a trifle faster. I'd expect nothing less but is it just vegetative matter (i.e. leaves) or also flowers? Hard to judge from pictures especially with the leaves obscuring half the plants. Harvest will hopefully tell...
BTW, I have the impression the non-defoliated plants grow a trifle faster. I'd expect nothing less but is it just vegetative matter (i.e. leaves) or also flowers? Hard to judge from pictures especially with the leaves obscuring half the plants. Harvest will hopefully tell...