A haploid is a cell or organism that has a single set of chromosomes that are not paired. The haploid gamete is normally produced during plant cell division. During fertilization, these cells normally merge with other similar haploid cells. A haploid cell only has half the number of chromosomes as are present in diploids.

A method is presented by which hundreds of haploid plants of various species of Nicotiana can be raised from pollen grains. Stamens should be excised when pollen grains have been individualized, but are still uninucleate and free of starch. When grown in vitro on a relatively simple medium, some pollen grains proliferate into embryo-liké, structures which develop in stages similar to those of zygotic embryos. The plantlets mature and flower profusely, but do not set seed.

Plant breeding is the purposeful manipulation of plant species in order to create desired genotypes and phenotypes for specific purposes. 

This manipulation involves either controlled pollination, genetic engineering, or both, followed by artificial selection of progeny. Plant breeding often, but not always, leads to plant domestication. 

Plant breeding has been practiced for thousands of years, since near the beginning of human civilization. It is now practiced worldwide by government institutions and commercial enterprises. International development agencies believe that breeding new crops is important for ensuring food security and developing practices through the development of crops suitable for their environment.