Iqrar A. Khan and Walter J. Kender

Institute of Horticultural Sciences, University of Agriculture, Faisalabad 38040, Pakistan and Nuclear Institute for Agriculture and Biology, Faisalabad, Pakistan

As our early ancestors evolved from the process of nomadic food gathering to devel- oping permanent food sources, crop breed- ing became an established practice. Over the centuries, humans selected, propagated and disseminated useful species that they chose to cultivate to feed the expanding populations. The hundreds of fruits, vegeta- bles and grains that are now found on the supermarket shelves are each the result of the activities of plant breeders.

In 1865, the discovery of Gregor Mendel’s laws of heredity became a turning point in the founding of the science of modern genetics, which transformed plant breeding into a modern scientifi c disci- pline. Mendel’s critical and painstaking experiments allowed other plant breeders to conduct even more advanced studies on hybridization, which evolved into a remarkable success story. Consider the abundance of nutritious cultivars, the development of hybrid vigour in agronomic crops such as sorghum and maize, the development of short stature wheat and rice cultivars leading to the Green Revolution and elimination of extensive crop failures caused by southern corn leaf blight, or wheat rust or historic potato blight.

Until Mendel’s paper on inheritance and its rediscovery at the turn of last century, plant breeding was based on traditional knowl- edge. Selection of desirable phenotypes was the primary means of perpetuating species. Plant breeding, now a scientifi c discipline, has resulted in major changes in how we feed the world’s population through superior cultivars.

It can be said that the successful devel- opment of commercial crop industries around the world is directly related to the success of plant breeding programmes. The subject of citrus breeding and allied tech- niques has been reviewed previously (Cameron and Frost, 1968; Soost and Roose, 1996; Grosser and Gmitter, 2005). This book is a consolidation of the current status of science and technology relevant to citrus breeding.