In natural systems before the advent of pesticides a plants survival of the fittest strategy would be to collect all the nutrients necessary to ensure natural protection from the elements using nutrition accumulation as their defense. Once man began selecting for the traits we desire (normally yield or flavor/sweetness) those natural mechanism no longer apply. Plus, yield tends to dilute the nutrient supply in a crop. If we used the same level of science we have used to “protect” crops from disease by using chemicals to find ways to deliver nutrients to our crops I believe we could return nutrient density back to our crops. Unfortunately, there currently is very little financial incentive available to do so.