Hi Sreekanth
Ginger and Turmeric can be grown during the initial two years of the rubber plantations. Vegetables like cowpea, cucumber, ladies finger, amaranthus etc. can be grown during the initial 2-3 years with proper addition of organic manures.
Advantage of growing bananas is that, the pseudo stem, leaves and mother rhizome left after harvest can be used for mulching the rubber plant.Pineapple is a good inter cop during initial four years. Two or three rows of pineapple suckers are planted along the inter rows of rubber in trenches during the year of planting of rubber.
Regards
Ashwini