Selection methods in plant breeding based on mode of reproduction

Plant breeders use different methods depending on the mode of reproduction of crops, which include: Self-fertilization, where pollen from a plant will fertilise reproductive cells or ovules of the same plant Cross-pollination, where pollen from one plant can only fertilize a different plant Asexual propagation (e.g. runners from strawberry plants) where the new plant is genetically identical to its parent Apomixis (self-cloning), where seeds are produced asexually and the new plant is genetically identical to its parent The mode of reproduction of a crop determines its genetic composition, which, in turn, is the deciding factor to develop suitable breeding and selection methods. Knowledge of mode of reproduction is also essential for its artificial manipulation to breed improved types. Only those breeding and selection methods are suitable for a crop which does not interfere with its natural state or ensure the maintenance of such a state. It is due to such reasons that imposition of self-fertilization on cross-pollinating crops leads to drastic reduction in their performance. For teaching purpose, plant breeding is presented as four categories: Line breeding (autogamous crops), population breeding (allogamous crops), hybrid breeding (mostly allogamous crops, some autogamous crops), clone breeding (vegetatively propagated crops). Certain restrictions caused the mechanisms for self-fertilization (partial and full self-fertilization) to develop in a number of plant species. Some of the reasons why a self-fertilizing method of reproduction is so effective are the efficacy of reproduction, as well as decreasing genetic variation and thus the fixation of highly adapted genotypes. Almost no inbreeding depression occurs in self-fertilizing plants because the mode of reproduction allows natural selection to take place in wild populations of such plants. Critical steps in the improvement of self-fertilizing crops are the choice of parents and the identification of the best plants in segregating generations.