Experiment Summary Statements

At this stage of Dr. Specht’s genetic experiment he could make these summary statements: 

  1. The mutagen applied to the true breeding seed induced phenotype variations in the soybeans. Dozens of unique phenotypes were discovered in the plots of M2 plants while unique phenotypes would rarely be observed in the original true breeding soybean line. 
  2. The mutagen induced mutations or changes in the genetic makeup inside of the plants. These genetic changes were passed on to offspring and therefore the unique phenotypes were inherited. 
  3. The genetic makeup of the M2 plants with mutations was not always the same. Some were homozygous and truebreeding and others were heterozygous. 
  4. The mutations were random. The original true breeding line was a determinant type soybean, which means it quit growing and producing flowers about mid July. A mutation that causes a change in this phenotype to the indeterminate type which continues to grow and flower would be easy to see in the field. Despite his hours of observation, Dr. Specht never found this mutant and therefore could not study the genetic control of this trait. He did however observe some other interesting mutants. These phenotypes had never been reported in soybean. Therefore Dr Specht continued this experiment but took a different approach to study the inheritance of other traits.