254 



BREEDING CROP PLANTS 



TABLE LXV. TRANSMISSION OF RUST RESISTANCE IN ASPARAGUS 



Giant. Two or three other females have been selected and the 

 crossed seed obtained from these selected plants has been distrib- 

 uted under the name Washington asparagus (Norton, 1919). 

 Some of these strains are now being offered for sale by commercial 

 seedsmen. 



Norton suggests the following method for breeding asparagus; 

 After two mated plants have proved their value by the progeny 

 test, they should be dug up and propagated by crown division. 

 These clones are isolated together and retained exclusively as 

 breeding stock. Isolation may be accomplished by a fine-meshed 

 cage to prevent the entrance of bees or by planting at a safe 

 distance from other beds of asparagus. Producing seed in a 

 greenhouse by hand pollination has also been found successful. 



ECONOMIC CUCURBITACE^ 



Introduction and Classification. The family Cucurbitacece 

 is of considerable historical interest. Sageret (1826) and Naudin 

 (1856, 1859a, 18596), two pre-Mendelian workers, made extensive 

 hybridization studies with some species belonging to this family. 

 Naudin made a species classification on the basis of genetic 

 behavior which is accepted at the present time. All the forms 

 which cross readily were placed in the same species group. 



