Effect of number of seed bulked and population size on genetic variability when using the multiple-seed procedure of SSD
2001
Macchiavelli, R. | Beaver, J.S.
Single-seed descent is used by grain legume breeders to maintain genetic variability in populations of advanced generation lines. To reduce labor costs, breeders often use a multiple-seed procedure in which a single pod rather than a single seed is harvested from each plant and bulked. This paper studied the distribution of the proportion of original F2 plants represented after advancing populations ranging from 100 to 600 plants from the F2 to the F6 generation when the multiple-seed procedure of SSD is used. Since the analytical solution to this problem is intractable, involving a 4-fold convolution of a hypergeometric distribution, a simulation was run in SAS to estimate this probability distribution. An increase in the size of the population advanced from the F2 to the F6 generation did not influence significantly the mean proportion of F2 plants represented in the F6 generation but decreased its variability. An increase in the number of seed per pod from two to six reduced the mean proportion of F2 plants represented in the F6 generation from 0.45 to 0.35, but did not decrease significantly the standard deviations of the distributions. Using the multiple-seed procedure, grain legume breeders could expect, on the average, that at least every third F6 line would be derived from a different F2 plant. This should generate considerable genetic variability for the selection for quantitatively inherited traits such as seed yield.
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