Glossary Plant Breeding

Micronaire. An instrument that measures the rate of airflow through a standard volume
of cotton. From its readings, fibre fineness and maturity of cotton samples may be
compared.
Micropyle. The usual point of entry for pollen tube in the embryo sac.
Micropropagation. In vitro propagation of plants from very small tissues (parts). It is
one of the best and most successful examples of the commercial application of tissue
culture technology. Advantages of micropropagation include: (a) identical progeny
true-to-the mother plant, (b) rapid and large-scale multiplication of elite genotypes,
and (c) rejuvenation of old clones/varieties. Besides, it is season-neutral and
facilitates germplasm exchange by avoiding the risk of spreading pathogens and
insect-pests.
Microsatellite. A type of repetitive DNA based on very short repeats such as
dinucleotides.
Microspecies. A small breeding population with limited variability. It may be a biotype
of the species.
Microspore. One of the four haploid spores originating from meiotic division of
microspore mother cell in the anther and which gives rise to the pollen grain.
Microspore Mother Cell. The diploid cell (2n) in the anther, which gives rise, through
meiosis, to four haploid microspores.
Microsporocyte. Themicrosporemothercell(or pollen mother cell).
Midparent Value. The mean value of a quantitative phenotype obtained from two
specific parents; the arithmetic mean of two parents with respect to a trait(s). For
instance, if a parent is 20 unit on the phenotypic scale of measurement and the second
one 30 unit, the midparent value will be 25 unit [MP=(20+30)/2].
Migration. Any form of introduction of genes (individuals) from one population into
another. It can be responsible for introducing new genes or moving up or downwards
the frequency of genes already present in the breeders’ or natural populations. The
change in frequency of the gene already present is expressed as: p =m(P-p t ),
whereas, m is the proportion of migrants, P is frequency in donor population, and p t is
frequency in the recipient population. Clearly there will be no change in the gene
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