seeking information about tomato leaf curl
I've read the article indicating the different reasons and possibilities for leaf curl, but in cases where it is not seemingly a virus, there was not much info in the way of possible nutrient deficiency or what could be done to help the plant.
Certified GKH Gardening Expert
If the leaves are curling and there is little yellowing on the plant, the curling is likely environmental and not an issue. Generally, the weather, which in most areas is extremely hot right now, is to blame and will clear up on its own. All you can really do is make sure the plants receive plenty of water. If the plant is yellowing as well, especially accompanied by spotting or wilting, it is likely disease. If they are diseased, there is little to do but pull up the plants and rotate new plantings to a new location.
The best way to tell if you have a nutrient deficiency of some kind is to have the soil tested. Then you can treat the plants accoding to the results.