Methods of crop improvement are explained below:

1. Hybridisation:

It is the crossing between two genetically dissimilar plants to produce a new variety of plants.

Crossing may be between two different varieties (intervarietal cross-breeding), between two different species of the same genus (interspecific cross-breeding), and between different genera (intergeneric cross-breeding). It incorporates desirable traits of both the parents in one variety.

2. Recombinant DNA technology: It is a method of transferring genes from one organism to another to modify the genetic make-up of latter. It gives rise to transgenic plants called as genetically modified foods (GMFs).

Example: Bt cotton is a genetically modified crop that carries bacterial genes that protect plants from insects.

3. Polyploidy: It refers to increasing the chromosome number of a plant that leads to increase in the plant production.

Example: Potato.

4. Mutation breeding: In this method, new crop varieties are generated by inducing mutations.

Example: Mexican varieties of wheat.

Improved varieties of:

(i) Rice is Jawahar.

(ii) Maize is HIM128.

(iii) Soya bean is Pusa 24.

(iv) Sunflower is MSF H 8.

(v) Mustard is Agarni.