Genetic Shifts in Mixed Bean Populations. I. Storage Effects1
- Eric E. Roos2
A mixture containing equal numbers of seed of eight snap bean (Phaseolus vulgaris L.) cultivars was prepared to determine the effects of seed aging on genetic shifts in the population. The mixture was artificially aged to simulate long-term storage using elevated storage temperatures and relative humidities/seed moisture contents. After seed aging, germination of each cultivar was regressed on the germination of the mixture to develop a series of equations which could be used to predict relative germination of the eight cultivars at any given level of germination for the mixture. Relative germination is defined as the ratio of the germination percentage of any cultivar to that of the highest germinating cultivar. At 50% mixture germination, the relative germination of the eight cultivars ranged from 1.00 (Cherokee Wax) to 0.49 (White Seeded Tendercrop). Computer simulation of the effects of repeated cycles of aging to reduce viability of the mixture to 50% predicted that four of the eight cultivars would be eliminated after eleven cycles, assuming a population size of 64 seeds for each cycle. The results of this experiment demonstrate the potential for loss in genetic variability within heterogeneous germplasm accessions during long-term storage.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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