Hayes and Garber - Cucurbit Breeding

298 BREEDING CROP PLANTS
Replication. Systematic repetition. Used in field work to designate the
systematic distribution of plots of each strain or variety to overcome soil
heterogeneity. Two replications means the use of three plots systematically
distributed.
Roguing. The act of removing undesirable individuals from a varietal
mixture in the field by hand selection.
Seed. The mature ovule, consisting of the kernel and its proper coat.
Self-fertilization. The union of the egg cell of one individual with the
sperm cell of the same individual.
Self -sterility. That condition in which the male gametes of an organism
are incapable of fertilizing the female gametes of the same individual.
Segregate. With reference to Mendelian unit-characters, to become
separated through the independent distribution of the genetic factors
before or at the time of the formation of the gametes.
Sex-linked Inheritance. The association of the determiner for any unitcharacter
with a sex-determiner, in such a manner that the two determiners
are either generally included in the same gamete, or that they are generally
included in different gametes.
Somatic Segregation. Segregation during somatic division.
Species. A group of varieties or a single variety which in botanical
characters and genetic relationship can be differentiated from another group
or variety belonging to the same genus or to other genera.
Spikelet. A small or secondary spike, especially in the inflorescence of
grasses.
Spike. A simple inflorescence with the flowers sessile or nearly so on a
more or less elongated common axis or rachis.
Sperm or Sperm Cell. Male sex-cell.
Standard Deviation. An absolute measurement of variation in terms of
the mean. The square root of the sum of the deviations squared divided
,by the number of variates.
Sterility. Inability to reproduce; when male and female gametes, through
incompatibility or some other cause, are incapable of mating or fertilization.
Strain. A group within a variety which constantly differs in genetic
factors or a single genetic factor difference from other strains of the same
variety.
Tassel. Used to designate the staminate inflorescence of maize.
Unit -character. In Mendelian inheritance, a character or alternative
difference of any kind, which is either present or absent, as a whole, in each
individual, and which is capable of becoming associated in new combinations
with other unit-characters.
Variate. A single magnitude determination of a character.
Variety. A group of strains or a single strain which by its structural or
functional characters can be differentiated from another variety.
Variety Group. A complex of varieties which resemble each other more
than varieties belonging to a different group. Of lower grade than species.
Xenia. The apparent immediate effect of pollen. It results from
double fertilization.
Zygote. The body formed by the union of two gametes and containing
2x number of chromosomes.