I am looking for a fruit tree which I can make into a bonsai, but I have a lack of patience. Please suggest a fast growing tree in Delhi environment that could easily be bonsai.
A bit unconventional, but if you want something that will grow quickly, train well & produce beautiful flowers and fruit with proper care, you could try a chili plant. fatalii.net has some wonderful examples of chili plants trained like bonsai. Scroll down his page for info on growing & more photos.
Results like some of those on his website can be achieved in less than a year & the plants, if taken care of well, can live for many many years!
If something like that is not appealing to you, Mulberries are sometimes used for bonsai & are relatively fast growing (perhaps the white mulberry "Morus alba" would be a good choice).
For the quickest results, you would want to collect a reasonably grown wild specimen, or purchase one locally rather than grow from seed.
I am working on several mulberry white and black when one plant I collected the parent plant over 30 years old had several stalks rooted and had leaves that were attached to the main stump I quickly cut them away and planted them now the are fruit bearing mini trees like a tiny orchard ..very happy I collected my own specimen..