Principles of Plant Breeding (2+1)

Recurrent selection for General combining ability

• Recurrent selection for general combining ability was proposed by Jenkins 1935. The progenies are crossed with tester strain with a broad genetic base. So plants are selected on the basis of superior performance of their plant X tester progenies would have superior GCA.

First Year:
A number of phenotypically outstanding plants are selected from the source population. The source population may be open pollinated, synthetics or advanced generation of a hybrid. Selected plant areselfed as well as crossed (as male) to a number of randomly selected plants form a tester having broad genetic base. Selected seeds are harvested separately and saved for planting in the third year. The test cross progeny from each selected plant is harvested separately and used for replicated yield trial in the second year.

Second Year:
A replicated yield trial is conducted using plant X tester progeny. Superior progeny are identified. Selected seeds form the first year from those plants that produced superior test cross progenies are planted in separate progeny row in a crossing block. These are inter crossed in all possible combination, equal amount of seeds from all the inter crosses are composited to obtain next generation. This completes the original cycle of selection.

Fourth year:
Seed obtained from bulking of all the inter crosses are planted as the source population for the first cycle of recurrent selection. Several plants are selected on the basis of their phenotypes. Each of them isselfed as well as crossed (as male) to a number of random plants form the tester with broad genetic base.

Fifth year:
Operation of second year is repeated.

Sixth year:
Operation of third year is repeated. This completes the first recurrent selection cycle.

Seventh year:
The second recurrent selection cycle may be initiated. This method improves the GCA in the direction of selection. It increases the yielding ability of the populations to isolate inbreds with superior GCA.