(a) Plant breeding is the science of changing the genetics of plants in order to produce desired characteristics. Plant breeding can be done through many different techniques ranging from simply selecting plants with desirable characteristics for propagation. 

Classical plant breeding uses : 

(i) Deliberate interbreeding (crossing) of closely or distantly related individuals to produce new crop varieties with desirable properties. 

(ii) In-vitro techniques such as protoplast fusion, mutagenic. 

(b) Mutagenic agents such as radiation and certain chemicals, are used to induce mutations and generate genetic variations from which desired mutants may be selected. Treatment with mutagens alters genes or breaks chromosomes. Gene mutation occurs naturally as errors in DNA replication, e.g., a mutant of paddy rice. 

(c) Plant breeding helps in increased food production by :

(1) Development of high-yielding crops. 

(2) Improved management practices. 

(3) Provisions of genetically derived better seed germplasm. Breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats is the most practical means to improve public health. 

Examples of crop plants with enhanced nutritional qualities and which have been developed by IARI New Delhi are :

(i) Golden maize : This is a hybrid variety which is rich in amino acids lysine and tryptophan' 

(ii) Wheat variety Atlas-60 : It is protein rich variety. 

(iii) Golden rice : It is iron rich fortified variety of rice.