That plant grown under constant (24/0) light sure must have used a lot of energy for growing roots. It has me wondering why and whether that's a beneficial use of resources. My initial thought has to do with storage of sugars in the roots. If it constantly stores sugars but never has an opportunity to use them (i.e., a dark period), then it would constantly need to create more storage space, so it grows more roots to store more sugars than it can use. If that's true, then it would be a compelling reason not to use 24/0 light, except during early life stages when root growth needs to be a priority.