Glossary Plant Breeding

Staminate flower. A flower bearing stamens but no pistil.
Standard Deviation (Fisher 1913). A measure of variability. This statistic ‘s’ [or
parameter ‘σ’] is defined as the square root of the average squared deviations of the
individual observations from their mean [di 2 /N] ½ . This statistic is used more
frequently in plant breeding experiments. It quantifies the variability of a character in
the same unit in which observations themselves are measured. Thus it is more useful
than variance, which is square of standard deviation.
Standard Error. A statistic, which is the estimate of the standard deviation (parameter).
It is the standard deviation of the sample means.
Standard Type. An arbitrarily specified gene or genotype taken as the basis of
comparison for genetic investigations. The standard genes are designated as ‘+’
irrespective of whether being dominant or recessive. However, the designated
standard types are supposed to be the most frequent types in nature. Also called wild
types.
Staple Length. Also called fibre length; the normal length of a typical portion of the
fibres of a cotton sample.
Statistic. Any function based on sample values. It is the estimate of a parameter made
from a sample. It strictly applies to a sample whereas a parameter to a population.
Statistical Distribution. The array of frequencies of different qualitative or quantitative
classes in a population.
Statistics. A branch of mathematics, which deals with collection, analysis and
interpretation of numerical data.
Stem Cell. The germ cell; an undifferentiated cell capable of giving rise to specialized
daughter cells.
Sterility. A condition in which plant fails to produce functional gametes. It may be
caused by chromosomal aberrations (structural or numerical), gene action or
cytoplasmic effects which may, in turn, lead to abortion or modification of entire
flower-buds, stamens, pistils or may disrupt the development of pollen, embryo sac,
embryo or endosperm.
Stigma. The portion of the pistil that receives the pollen.
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