In cross pollinated crops, the mixture of genotype from several sources is maintained bulk from one generation to the next is referred as composite variety.
Composite variety is a variety derived from advance generation of random mated out standing lines (Germplasm inbreds, varieties, hybrids, advance generation lines).
Mixing the seeds of several phenotypically outstanding lines produces a composite variety and encouraging open pollination to produce crosses in all combinations among, the mixed lines. The lines used to produce a composite variety are rarely tested for combining ability with each other like synthetic composite are commercial varieties and are maintained by open – pollination in isolation. Mixing the seeds of various genotypes, which are similar in maturity height, seed size, colour, etc. develops composite varieties. The variety is maintained by open pollination. Farmers can use their own seed for 3 to 4 years.
Procedure for Development Composite Variety:
There is no restriction to the number of lines included in the development of composite , but the line possessing desirable characteristics should be selected like earliness, insect resistance, drought and frost resistance can be included in the development. The seeds of desired selected lines mixed together and random mating is allowed for 4-5 generations. In the subsequent generation of random mating, the undesirable types are eliminated to achieve uniformity and homogeneity in various morphological characters. Such uniform population is tested in replicated trials, across environment along with standards checks and high yielding stable type can be released as composite variety. The combining ability of lines used in composite are not tested, whereas in synthetic each of the component is tested for its combining ability.
Achievement of Composite Varieties:
In India six composite varieties of maize like Amber, Jawahar, Kisan Vikram, sona and Vijay have been released in 1967. Subsequently number of composite has been released in Bajara and other crops. Some of the released composite of maize are Co-1 , NLD , Renuka and Kanchan, Diara-3 etc, while in Bajara released composite are WCC-75, RCBIC-9, ICTP-8203.