Abstract

In Cytogenetics and Plant breeding, the conventional methods of collection, introduction, selection and hybridisation have been in use in this department since its inception. These methods are the most certain and are the basic ones for obtaining the desired plant selec- tions. In the investigation of the fundamentals of genetics, much ground has been covered in the several crop plants, some systematic and others as and when the occasion arose. The storehouse of all desired characters has been in the wild plants from which the cultivated ones have been later selected. We have often to go back to nature to incorporate certain required characters into the cultivated type and also to invigorate it, make it resistant towards pests, diseases and adverse conditions. The scientist also watches for suitable mutations to occur in the homozygous materials. These occur at very low rates. Attempts have been made to increase the rate of incidence of such mutations by the application of agencies which cause changes in the heritable material. The concep- tion of the gene or the heritable unit is still nebulous, though something is known about their location, arrangement and constitution. The gene cannot be newly created but an existing gene can be made to change by readjustment of its molecular structure. In taking recourse to hy- bridisation whether it be intervarietal, interspecific or intergeneric, only gene recombinations are produced.

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