I have 4 tomatoes in a bed, 4 in very large pots and 4 in 5 gal buckets. I won't put anything except maybe dwarf varieties or determinates in buckets again. At least not in summer. The AR Traveler in the bucket has lower leaves that are VERY yellow. I found a pic of salt damage and this is what this plant looks like. One of the other bucket plants is kind of yellow, but not as distinctive as the traveler. I have some pole beans in buckets that are very yellow, too. I have been blaming poor drainage or too much heat or disease. Do any of you have experience with this? Some of what I have read suggests salt buildup is common in container plants. I don't have a rain barrel, and as soon as I put one in it would quit raining anyway. And then there are the spider mites. And I saw my first squash bugs today, on the volunteer in the compost pile. Whine, whine, whine.

Here is a link that might be useful: Salt damage on Tomato