Loss of genetic diversity

There are 50,000 known edible plants documented world wide .Of these,only 15 varieities produce 90% of the world's food.Modern agricultural practices have resulted in a serious loss of gentic variability of crops .India's distinctive treditional varieties of rice alone are said to have numbered between 30 and 50,000.
Most of these have been lost to the farmer during the last few decades,as multinational seed companies aggressively push a few commercial genotypes.This Creates a risk to our food security,as farmers can lose all their produce due to rapidly spreading disease.On the other hand,a cereal that has multiple varieties growing in different locations does not permit the rapid spread of a disease.
The most effective method to introduced describle traits in to crops is by using characterstics found in the wild relatives of crop plants.As the widerness shrinks ,these varieties are rapidly disappeaing, once they are completely lost,their desirable characteristics cannot be introduced when found necessery in the future.Ensuring long-term food security may depend on conserving the wild relatives of crop plants in national parks and wild life sanctuaries.
In plant gentic losses world wide are not slowed down,some estimates show that as many as 60,000 plant spices,which accounts for 25% of the world's total ,will be lost by the 2025.The most economical way to prevent this is by expending the network and coverage of our protected Areas.Collections in germplasm,seed banks and tissue culture facilitiescare other possible ways to prevent extintion,but these are extremely expensive.