Plant Breeding

Plant breeding is the science of improving crop varieties so that they yield more, are of better quality, resist disease, and mature in a shorter time suited to their growing environment. In essence, it is the purposeful manipulation of a plant species to create a genotype and phenotype that benefit people. In its earliest days, plant breeding depended almost entirely on the skill and judgement of the individual breeder; once the principles of genetics and cytogenetics were understood, systematic methods — selection, introduction, hybridisation, ploidy manipulation, mutation, tissue culture and, more recently, biotechnology — were developed to produce improved varieties in a far more predictable way. Figure 9.10 traces this progress as a timeline of milestones, from the domestication of crops by early farmers roughly 10,000 years ago, through Mendel's laws of inheritance (1865) and the discovery of the DNA double helix by Watson and Crick (1953), to marker-assisted selection, genetically modified organisms, and today's genome-editing-based …