Plant breeding systems

Abstract

New concepts in population genetics call for reappraisal of plant breeding procedures; this commentary evaluates certain breeding procedures according to their probable effectiveness in promoting maximum gene recombinations and achieving maximum fitness. Breeding is viewed as an accelerated evolutionary process where appropriate design and control substitute for long duration of complex interactions of genotype with environment in the wild state. Crossing selected sibs in early generations is a means of re-assembling adaptive genes capable of functioning in a balanced polygenic system. The probability that any one individual in early generations after a cross would carry all or most of the potentially co-adaptive genes is very remote; hence strict inbreeding or pure line selection from early generations will not produce the best balanced genotypes. The recombination of two or more partly balanced genotypes by sib crossing magnifies the chance that a maximum number of harmoniously functioning genes will be assembled and through subsequent inbreeding emerge as stable and widely adapted varieties. Breeding procedures are viewed in perspective as they proceed from maximum inbreeding to maximum interbreeding or from pure line selection to bulk selection with natural or enforced sib-crossing.