I have two Japanese eggplants each in 5 gallon buckets. They were pretty grown up when I planted them. One of it is showing brown spots on leaves and in some places dried spots. I have attached the photos of leaves. Is this disease or nutrition/water problem or something else?
Only one plant was showing the spots first, now the other one has one leaf with a couple spots.
It rained a lot after I planted them but has been really sunny and warm after.

Bhingri,
Looks like the beginning of cercospora leaf spot (a fungal issue). I have had some success treating similar issues with a diluted Neem oil spray. Eggplants seem to be relatively tricky plants to grow... we have some that we grew from seed at the nursery I work at and they seem to be pretty prone to insect damage, nutrient deficiency, fungal issues, etc.
If it is a fungal problem, try to minimize the amount of moisture/humidity around your plants, particularly late in the day and into the evening. Also, crowding of foliage (from other eggplants, weeds, or otherwise) can provide ideal conditions for fungus to thrive...

Good luck!

- Meghan

Thank you! I will use neem oil spray.
It is raining again for a day and some. There is no way I can reduce moisture around plants. They are in two separate buckets far from each other so plenty of space for air flow, no crowding.

You're welcome! And don't give up on the Neem oil if it doesn't seem to work right away... in my experience, it usually takes 3 or so applications at 7 to 14 day intervals. Make sure you get the top AND bottom of the leaves. It's kind of a pain but it seems to be pretty effective.

- Meghan