INTRODUCTION TO PLANT BREEDING

AGRONOMY 815 / CLASS ASSIGNMENTS


P. STEPHEN BAENZIGER, 338 Keim Hall, 472-1538

DEPARTMENT OF AGRONOMY / UNIVERSITY OF NEBRASKA



PROBLEM SET 8Due December 11, 1997

Name: ________________________________________________________________________



  1. What is the difference between a Center of Diversity and a Center of Origin? How can a biologist tell the difference between the two? (3 points)




    If you discovered a new disease on an important crop in your country, where would you go to get resistant germplasm (be specific)? Why? (3 points)





    Why are gemplasm/seed banks important? (3 points)





  2. You have a population of 400 corn plants. After pollination, you select 50 ears (1 from each of 50 plants). What is your effective population size? (3 points)







  3. You are working with a random mating population of 1000 plants. You discover that 57 plants are susceptible to a new leaf disease. Assume resistance and susceptibility is controlled by one gene (genotype is rr for susceptibility and RR for resistance).


    What is this genotypic frequency of susceptible plants?


    What is the gene frequency for R? What is the gene frequency for r?




    How many generations would it take to reduce the genotypic frequency of susceptible plants in the population to 1%, (i.e. 10 in 1000) by selecting against the susceptible plants?