Lysenko, Trofim Denisovich, lih SEHNG koh, trah FEEM deh NEE so vihch (1898-1976), was the most important biologist in the Soviet Union from the mid-1930's to the late 1950's. Soviet dictator Joseph Stalin supported Lysenko's theories for improving farm production because they promised quick success. However, Lysenko's theories did not lead to agricultural improvements, and later Soviet leaders blamed them for slowing the growth of the country's agriculture. Lysenko held back Soviet research in genetics (the science of heredity) for more than 20 years.