Method of Plant Breeding in Cross Pollinated Plants – Selection with Progeny Testing
With Progeny Testing:
In this method initial plants are selected on the basis of their phenotype, but the final selection of plant based on progeny test. This method includes progeny selection on ear to row method and recurrent selection.
Progeny Selection (Ear to Row Method):
Hopkins in 1908 developed this method, extensively used in maize. In its simplest form it consists of
i) 50- 100 number of plants are selected on the basis of their phenotype and are allowed to open pollinate. The seeds from individual plants are harvested separately.
ii) A single row of 10-50 plants i.e a progeny row, is grown from each selected plant. The progeny rows are evaluated for desirable character and superior are identified.
iii) Several phenotypically superior plants are selected from the superior progenies and selected plants are permitted to open pollinate.
iv) Small progeny rows are again grown from the selected plants, and the process of selection is repeated.
This method is relatively simple and the selection cycle is of one year only. However, it suffers from the defect that the weak and inferior progenies pollinate plants in the superior progenies. This reduces the effectiveness of selection.
Merits of Ear to Row Method:
1) In this method the selection is based on the progeny test and not phenotype of individual plants, hence it is more efficient than mass selection in the identification of superior genotypes.
2) Inbreeding may be avoided to certain extent by selecting sufficiently large number of progenies.
3) It is simple and easy.
Demerits Ear to Row Method:
1) There is no control on pollination and plants are allowed to open pollinate, thus selection is based on maternal parent only. This reduces the efficiency of selection.
2) Many progeny selection schemes are complicated and involve considerable work.
3) The selection cycle is usually of the two years. Thus , time requirement for selection is twice as that of mass selection.
Plant to Row Method:
Louis De Vilmorin first used it for improvement of Sugarbeet. In this number of plants are selected and they are open pollinated and the individual plants are harvested separately. The progeny rows are grown from each selected plant and are evaluated for desirable character. The superior progenies are identified. Several similar plants are selected from the progenies and allowed to open pollinate thus selection process is repeated. This method helps to know the superiority of plants, whether due to environment or genetic variation. Similarly by growing progenies of 8 to 58 plants, range of genetic variability can be established. E. g Cotton, Jute, Sunflower and Castor, etc.