Glossary Plant Breeding

Ochre Codon. One of the stop codons, UAA.
Ocimene. A volatile terpene found in certain legumes. Its amount varies among clones,
and thus ocimene content may be altered by breeding, suggesting that clones with
improved attractiveness for honeybee visitation could be developed.
Octad. A group of eight ascospores contained in an ascus. It is produced in species in
which the tetrad normally undergoes a post-meiotic mitotic division.
ODV. Other Distinguishable Varieties; seeds of other varieties with distinct appearance
present in a seed lot of designated variety.
OECD. Organization for Economic Cooperation and Development. OECD was
developed after the Second World War in Europe. The scheme developed for uniform
technology and standard methods and practice for seed production and certification
for forage moving in international trade was taken over by OECD in 1962. Since then,
it adopted and implemented schemes for certification of different kinds of seeds
including those of cereals, sugar beet, forestry, and the like. The basic objective of
OECD seed scheme is to encourage use of seed of high quality in the participating
countries. The scheme authorizes use of labels and certificates for seed produced and
processed for international trade according to the seed principles. The scheme is open
on voluntary basis to members of organization as well as to other member countries
of United Nations. If a country adopts OECD seed schemes, it is obliged to ensure
that the rules of the scheme are strictly observed.
Off - Season Nursery. A place wherein a breeding strain is grown in a season not suited
to its normal rearing. The off-season planting serves the purpose of advancing
generations, e.g., growing of off-season wheat and chickpea at Wellington (Tamil
Nadu) and Dharwad (Karnataka), respectively.
Okasaki Fragment. A small segment of single-stranded DNA synthesized as a part of
the lagging strand in DNA replication. The strand of the original DNA being used as
the template for lagging strand is unfolded in 3’ to 5’ direction; however, replication
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