The concept of combining ability is becoming increasingly important in plant and animal breeding. It is especially useful in connection with "testing" procedures, in which it is desired to study and compare the performances of lines in hybrid combination. Sunflower being a highly cross-pollinated crop has a great scope for increasing productivity by diversifying hybrid base. Therefore, sunflower researchers accelerated their effort to develop new diverse sources of CMS to widen the genetic base and to reduce the genetic vulnerability of sunflower hybrids. Besides, the development of new CMS sources in order to enhance the genetic diversity. Considering the fact, several diverse sources of CMS have been identified and being utilized in the CMS conversion programme. We hope that the information provided in the book will supplemented to the researchers in Plant Breeding field and encourage the research scholars to excavate various ideas for confronting with combining ability problems. We would like to place our sincere thanks to authors and publishers who helped us to complete the compilation of this book.Valuable suggestions are welcome for further enrichment of the same.