Self pollinators: Mass selection
Phenotypic selection is carried out to identify the "best" types from a segregating population, a landrace etc. The progeny of these selections are bulked to produce the next generation.
The idea is to increase the mean performance of the population as a whole.
The expected result is a genotypically heterogeneous population which performs better than the original.
Can be repeated over successive generations (until the genotypic variation has been exhausted).
The efficiency of the approach is very dependent on the heritability of the trait under selection.