Clone 2 Heterosis 2 Hybridization 2 Methods of Crop Improvement 2 Mutation Breeding 2 Crop modelibng 1 Hybrid Vigour 1 Hybrid vigour 1 MASS SELECTION 1 METHODS OF CROP IMPROVEMENT 1 MODE OF REPRODUCTION IN RELATION TO BREEDING METHODS 1 Methods of crop improvement 1 NATURE AND SCOPE OF PLANT BREEDING 1 Pure Line 1 Pure line 1 Root adaptation and crop production 1 Techniques of Crop production 1 The principle and effects of straw Ammoniation 1