The biggest constraint of plant breeding is:
a. availability of desirable gene in the crop and its wild relatives
b. infrastructure
c. trained manpower
d. transfer of genes from unrelated sources.
The answer is the option (a) availability of desirable gene in the crop and its wild relatives
Explanation: There is enough infrastructure available for the plant breeding and there is no any dearth of trained work force because of over thousands of years of experience in farming.