Glossary Plant Breeding

Apostatic Selection. Selection for rare genotypes.
Approach Crossing. A technique of artificial crossing that involves bagging of
emasculated inflorescence with the inflorescence of pollen parent. The shaking of the
bag daily helps disseminate the pollen to the stigma of emasculated flower. It usually
results in a higher percentage of seed setting because fresh pollen is shed over a long
period of several days. It has been successfully used in wheat and can also be used in
small grain and forage grasses.
Archesporium. A cell or group of cells formed by mitosis of the micro- and megaspore
mother cells.
Arrow. The inflorescence of sugar cane. The branch length of the panicle (inflorescence)
reduces towards the apex giving it a distinct arrow shape.
Artificial Neural Network (ANN). A network of nodes or inputs (like neurons) that are
processed in a non-linear fashion to provide a meaningful output. It may be used to
predict total food-grain production in a specific year on the basis of certain inputs or
variables such as fertilizer consumption, rainfall and other weather parameters.
Ascospore. A sexual spore from certain fungus species in which spores are found in a sac
(fruiting body) called an ascus.
Asexual Reproduction. A mode of reproduction that excludes involvement or union of
gametes or sex cells, that is, reproduction by somatic cells, tissues, or organs. The
ensuing individuals resemble almost exactly their parent. Asexually propagated
species in commercial practice reproduce by vegetative means; genetic segregation
and recombination do not occur in the successive clonal generations. These species
are highly heterozygous due to gradual accumulation of naturally occurring mutations.
They have higher levels of sterility due to constant disuse of sex. The clones of such
species, previously known to be resistant to pathogens (viruses and mycoplasma) and
pests, soon become susceptible due to either mutation of resistant genes or subsequent
changes in biotype composition of these pests and pathogens. This occurs because
genetic filter through meiosis is precluded in successive vegetative generations. This
factor, at the same time, also provides a clue why such species evolve in nature more
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