Glossary Plant Breeding

Integrated Plant Nutrition. A system to maintain soil fertility, sustaining productivity
and improving farmers’ profitability through judicious and efficient use of mineral
fertilizers, organic manures and biofertilizers.
Interbreeding. Hybridisation between genetically dissimilar individuals capable of
exchanging genetic information (genes). It holds individuals together in a population,
or populations together in a sub-species or species.
Intercalating Agent. A chemical that can insert itself between the stacked bases at the
centre of the double helix, possibly causing a frame-shift mutation.
Interchange Trisomic. A trisomic developed in such a way that two members of the
triplicate are interchanged chromosomes. It differs from a tertiary trisomic in having
two interchange chromosomes (instead of one in TT).
Interchromosomal Recombination. Recombination resulting from independent
assortment of nonhomologous chromosomes.
Interference. The effect of one crossover on the probability that another will occur in the
immediate vicinity. It is a measure of the independence of crossovers from each other,
and is calculated by subtracting the coefficient of coincidence from 1.
Interphase. The stage between nuclear divisions of the cell cycle, when chromosomes
are extended and functionally active.
Interploid Crosses. Crosses involving parents having different ploidy levels [e.g., a cross
between S. tuberosum (2n = 4x = 48) and S. phureja (2n = 2x = 24)]. Interploid
crosses are made sometimes to produce haploids, which may develop through
parthenogenesis or haploid apogamy.
Interspecific Hybridization. A method as well as design of evolution of crop plants. It
consists of crossing distinct taxonomic species with the preservation of improved
types from the segregation products. As many of the segregants have lower biological
fitness, its major application as a method of breeding has been mostly in vegetatively
propagated species.
Interstitial Region. The chromosomal region between the centromere and the site of a
rearrangement.
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