1 Design and Analysis of Experiments: Special Designs and Applications, First Edition. Edited by Klaus Hinkelmann. © 2012 John Wiley & Sons, Inc. Published 2012 by John Wiley & Sons, Inc. C H A P T E R 1 Genetic Crosses Experiments Murari Singh, Sudhir Gupta, and Rajender Parsad 1.1 INTRODUCTION A major objective of biometrical genetics is to explore the nature of gene action in determining quantitative traits. This also includes determination of the number of major genetic factors or genes responsible for the traits. The history of genetic experiments can be traced back to Mendel’s famous experiments on peas, the results of which he published in 1864. His work remained obscure until it was rediscovered independently by three scientists Hugo de Vries, Carl Correns, and Erich von Tschermak-Seysenegg, and published in 1900 (Monaghan and Corcos 1986, 1987); see http://www. eucarpia.org/secretariate/honorary/tschermak.html. Further genetic experi- mentation quickly followed these discoveries, and the subject of experimental genetics was thus founded. This chapter deals with the type of genetic experiments that help assess variability in observed quantitative traits arising from genetic factors, environ- mental factors, and their interactions. To generate information on the vari- ability, genetic entities, such as individual plants, animals, lines, clones, strains, and populations, are involved. Experimental design plays a twofold role in these experiments: a design to form genetic crosses and a design to evaluate the crosses in chosen environments. These two designs are called the mating design M and the environment design E, respectively. Some of the key resources in this area include standard texts and expository papers by Kempthorne (1956), Mather and Jinks (1982), Hayman (1954a, 1954b), Hinkelmann (1975), COPYRIGHTED MATERIAL