Breeding of Vegetable, Spice and Tuber crops (2+1)

Modification of the Bulk Method

• A modification of the bulk method based on artificial selection in F2 and the subsequent generations is outlines below.
• F2 and F3 Generations. F2 and F3 generations are space-planted and a large number (1,000-5,000) of desirable plants are harvested separately.

• F4 Generation. F4 is space – planted and 1,000 to 5,000 desirable plants are selected. Seeds from the selected plants are harvested separately.
• F5 Generation. Individual plant progenies are grown. Selection among progenies is based on plant height, disease resistance, lodging resistance, maturity date, fruit weight, fruit shape, number of fruits and other agronomic characteristics. Undesirable and inferior progenies are eliminated. Often only 10-30 per cent of the progenies may be saved. Seeds from each of the selected progenies are harvested in bulk.
• F6 Generation. A preliminary yield trial is planted using the bulk seeds from the selected individual plant progenies. Observations are recorded on agronomic characteristics and yield. Quality tests may be done on superior progenies.
• F7 Generation. Superior progenies selected on the basis of yield trial are space –planted for further purification. Individual plants are selected from the superior progenies and their seed is harvested separately.
• F8 Generation. Individual plant progenies are grown. Inferior progenies and progenies showing segregation are ordinarily rejected. Each selected progeny is harvested in bulk.
• F9 Generation. Preliminary yield trial is conducted to identify few superior progenies for detailed yield tests. Quality test is done to eliminate undesirable progenies.
• F10 – F13 Generations.Replicated yield trials are conducted at several locations with standard varieties as checks. The line or lines that are found to be superior to the standard checks would be released as new varieties.
• F13 Generation. Seed of the newly released variety is multiplied for distribution among the farmers.
• This modification of the bulk method provides an opportunity for the breeder to exercise his skill and judgment in selection of plant types in the early generations (F2 to F4). At the same time, it does not involve laborious record keeping as in the case with the pedigree method. Therefore, this modification has the appeal that it provides for selection in the early segregating generations and yet it involves less time and labour than the pedigree method.