I, along with a lot of other experienced growers, have a tendency to forget a lot of first time growers have never grown any kind of plant before, so we really need a sticky thread that's pretty much 'plant basics 101'. Proper watering is THE most important part of helping a plant to thrive. First of all, when you pot up a plant, always leave enough room between the pot rim & soil surface for water. About 1"-1 1/2" for party cups up to 4" pots, the bigger the pot, the more room for water. 6" for a 5 gal bucket, sometimes I'll give it 8". Let the top of the soil dry, stick your finger in it & feel for the moisture (some people heft the pot & go by weight). If its dry an inch or so down, time for water. DONT let it dry to the bottom of the pot unless its a damned cactus! You don't want it so dry the soil shrinks, but should that happen, water lightly, not enough to hit the sides of the pot, keep it in the center to make sure its absorbed rather that travelling down the side between the soil & the pot. This will cause the soil to expand & fill the pot again. Once that happens, fill the pot to the top with water. Making sure you've used enough water to 'run through'. I usually let it sit in the run off 2-3 min. If there were any dry pockets in the soil, they will absorb the water. Then dump the access out of the catch pot. Water again when the top inch or so becomes dry again. That would be for a party cup (don't forget to punch 4 drain holes in these guys) or a 4" pot. The bigger the pot, the deeper you go on the surface dryness. NEVER give anything other than plain water to a plant in bone dry soil or one that is dry enough to wilt. Anytime you've let them over dry, let them sit in the run off in the catch pot untill they stop absorbing water. This is NOT over watering. Over watering occurs when you water too FREQUENTLY, not allowing the soil to dry somewhat between waterings. The roots litterly drown from lack of oxygen. Perfectly watered soil is soil that is moist, but still has small air spaces between the soil particals. Well drained soil holds water within itself while allowing very small air spaces for roots to breathe. Fox farm soils are a good example of this. When using a rich organic soil such as fox farms, hold off on the nutes untill the plants say they they need it. Usually 2-3 wks after transplanting into bigger pot/fresh soil, & about 1/4 strength the first feed, 1/2 for a while. I never use high nitro/ growth nutes stronger than 1/2 recommended strength because I use rich soils. I even use tiger bloom 1/4, then 1/2, & then the recommended amount 1/2 way into budding. Remember, you feed the soil & the soil feeds the plant.
-- read this post more than once. What you've done is burn the hell out of the root hairs by feeding dry soil. Nitrogen is the worse for burning, & I can tell by the color & texture of the leaves that this is a nitrogen burn. Also, the fact that there's no 'gloss' at all to the leaves, I would say they've been water stressed for a while before the nute burn. Probably not watering through & leaving a dry air pocket just below the root ball. This probably happened after the roots filled the pots & the plants required more water than before, but the water amount wasn't changed as they changed. If you do the catch pot thing & let them sit in the run through water a few min you can prevent this from happening again. Remember, before you feed, make sure there is some moisture to be felt by your finger tip slightly below the soil surface.
-- Sounds like its possible you will loose the worst one, & the others will be stunted & yield decreased because of this, but with proper watering & backing off with the nutes for a while, they should survive & give you something to harvest. Everybody here has given you good, sound advice, but like I said, we do tend to forget first time growers have never grown anything before, so better late than never, I've given you the basics. I hope I've made it easy to understand, if not, just ask & one of us will clarify. Good luck & I'll make it a point to check your thread often.