The hybrid vigour or heterosis has been credited for large productivity gains in crops where hybrids are cultivated. This book seeks to provide an update into the advent and promise of hybrids through a comprehensive coverage of the theoretical and applied aspects of heterosis breeding. Its principal elements are the hybrid advantage, pollination control mechanisms and the production of hybrid seeds. Individual crop specialists have presented analyses of intricacies involved in the development of hybrids of rice, wheat, maize, barley, pearl millet, sorghum, cotton, sunflower, rapeseed-mustard, castor, pigeonpea, tomato, onion, cole crops, peppers, muskmelon and watermelon.