Glossary Plant Breeding

slowly compared to sexually reproducing ones as genetic variation through Mendelian
segregation and recombination is not generated.
Assortment. Matching or grouping of a chromosome with other non-homologous
chromosomes during cell division.
Asynapsis. Failure of pairing of homologous chromosomes during meiosis I.
Atavism. The sudden appearance of an ancestral character in the progeny. It may be due
to a mutation in an otherwise “inactive” gene or to a change in the position of that
gene (owing to inversion or translocation) or even deletion of the regulatory gene.
ATP. Adenosine triphosphate. It is usually used for energy storage in the living systems.
It is synthesized mainly in mitochondria and chloroplasts. The energy from the
breakdown of ATP drives many important reactions in the cell. There is no obvious
reason why ATP is better suited for energy storage than GTP, CTP or UTP. Among
the organic bases, the purine molecule, adenine is simply a pentamer of HCN and is
most readily synthesised. It may be that the relative simplicity of the synthesis of
adenine makes ATP better suited for energy storage than any other triphosphate of N-
bases.
AugmentedDesign(Federer 1956). An experimental design used to evaluate either
larger number of test genotypes or genotypes with small quantity of seeds.
Assessment of larger no. of genotypes is not possible with the most frequently used
design (RCBD) due to problems of soil heterogeneity. Similarly, lower quantity of
seeds of test genotypes poses problems in their replication. Augmented design has
been suggested to obviate these problems. The three proposed augmented designs are:
(1) Augmented Completely Randomized Design, (2) Augmented Randomized
Complete Block Design, and (3) Augmented Latin Square Design. The first of these is
most frequently used when seeds of test genotypes are small in quantity, whereas the
second is most fit under condition of larger number of test genotypes. It is worthmentioning
that what RCBD does by replicating the whole entries, augmented design
accomplishes the same by replicating only the checks and thus saving the space.
Autogamy. Self-fertilization.
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