Plant breeding has revolutionized agriculture through genetic modifications in plants to get desirable characteristics or species. It emphasizes on development of high-productivity crops either through simple propagation or by making changes at genetic level. This book is compiled in such a manner, that it will provide in-depth knowledge about the theory and practice of crop improvement, pollen behavior and food security. The various studies that are constantly contributing towards advancing technologies and evolution of this field are examined in detail. As this field is emerging at a rapid pace, the contents of this book will help the readers understand and analyze the modern concepts and applications of the subject.