At an agricultural university, they are pleased when annually they get over 1% greater yield from breeding
it is possible that PV lights, like photovoltaic pathlights, could function during the daytime to put light on the green grain awns (or upper leaves) causing sugars to accumulate right near the
growing grain kernel, causing it to grow larger. I wildly imagine a 5-10% yield improvement!
now, reflectorized mylar mulch has been discussed at the .5b The thing is, what if it were angled or positioned to favor the green awns or upper leaves? That might also be beneficial