Yes, you can, especially if it is a Macro Nutrient (N-P-K). You can also apply micro nutrients through the leaves, but only if it has been chelated. Most hydroponic companies have chelated micro nutes in their formulas. I recommend spraying with Liquid Karma and/or Cal Mag Plus. Most likely you are getting a cal mag deficiency, especially if you are in a hydro system with rockwool or coco media.
You say that it is only one plant that is showing this? Is it the plant that is closest to the intake? Is it a different strain or even a different phenotype?
I would just recommend going to MonsterGardens.com, or even call their hotline. They seem to be super knowledgeable when it comes to troubleshooting problems with my garden.