My daughter is a USA citizen. I can get a Green card as Parent (aged 79 yrs). I will not have any USA income. Will have Indian income (interest etc. Taxable in India ) How will this affect USA tax requirements. Do I have to pay tax on my Indian income in USA? Please reply. NARAIN

Every U.S. citizen or resident must file tax return if the worldwide income exceeds the filing requirements. So you must file tax return if your income exceeds the filing requirements. On your return you must report your world wide income.
If you paid taxes in the foreign country, you will claim credit for taxes paid in the foreign country by filing Form 1116 or can file form 2555 Foreign Earned Income Exclusion. Even if you have a filing requirement, the chances are you will not pay any U.S. tax or pay very little U.S. tax.
Another filing requirement is Form TD F 90-22.1. Your U.S. Tax Return: U.S. Citizen or Resident with Foreign Income