TGC REPORT No . 31, 1981 RESEARCH NOTES 20 hybrid L . esculentum - L . chilenese - L . puruvianum var . humifusum . It was easily crossed with var . humifusum (P 3 )and considerably less easily crossed with L . esculentum (P 1 ) used as female parent (Table 1) . With the aim of studying the reproductive relationships of BC 1 P 1 , self - pollination and backcross with the three parental species were made . With self - pollination, a large number of well - seeded fruits with normal seed viability were obtained, and they gave multiple F 1 's of BC 1 P 1 generation . The backcross with L . chilense (P 2 ) and L . peruvianum var . humifusum (P 3 ) was made without particular difficulties . The seeds obtained had over 75% viability . The resistance of the three parental species and the trigenomic hybrid to Corynebacterium michiganense was studied . Unlike L . esculentum which is highly susceptible, L . peruvianum var . humifusum showed high resistance to C . michiganense . In comparison to L . peruvianum var . humifusum, L . chilense exhibited lower resistance . The F 1 BC 1 P 1 plants differed among themselves in morphological traits as well as in resistance to C . michiganense . The accumulation of genes originating from the two wild parental species provided the obtainment of a considerable number of plants with different degrees of resistance . Those with highest resistance were used for making backcrosses with L . esculentum .