BIENNIAL REPORT, 1927 AND 1928 339 



of most cuttings are necessary for propagating asparagus cuttings. If 

 tlie cuttings are slightly dried before planting, there will be less danger 

 from decay attacking the soft tissue in the crowns. 



Roots on old plants serve merely as reserve food for the establishment of 

 tiie cutting, and new roots must be formed before the cutting can draw on 

 the soil moisture. Old roots do not send out secondary roots. New roots 

 (one year old) send out secondary roots, and if not injured will continue 

 to serve as feeder as well as storage roots. This is in a large measure 

 responsible for the greater ease with which one-year roots may be propa- 

 gated. 



On one-year crowns, roots that have been broken off will send out sec- 

 ondary roots but will not grow in length. (Occasionally a secondary root 

 near the broken end of the storage root will develop sufficiently to function 

 as a storage root. 



The Genetics of Greenhouse Cucumbers. (V. A. Tiedjens). A number 

 of ciiaracters liave been isolated in cucumbers. Green fruit color is 

 dominant over white; orange or bronze fruit color (sun color) linked 

 with the black spines, dominant over white and green fruit color, develops 

 only in the presence of light. Black spines are dominant over white spines. 

 Parthenocarpy is epistatic to development by fertilization. Tlie location 

 of pistillate flowers on the main stem is epistatic to the allelomorph in- 

 hibiting the production of pistillate flowers. The abundant production of 

 laterals is dominant to the absence of laterals. 



Such characters as size and shape of fruit, and number of flowers show 

 partial dominance or follow the laws of quantitative inheritance and are 

 materially influenced by environmental conditions. 



The following pure lines have been established: 



1. Types varying from abundant to very light sets of fruit and stam- 

 inate flowers. 



2. A selection having pistillate flowers on the central stem. 



3. A selection having no pistillate flowers on the central stem. 



4. Selections varying for color, size and shape of fruit. 



5. Selections that have spines and warts in various degrees of intensity. 

 A number of crosses involving certain relations have been made but 



insufficient data are available to draw conclusions. 



A commercial variety that will combine desirable market qualities and 

 develop parthenocarpically is under observation. The extreme heterozy- 

 gous condition of cucumber varieties makes it necessary that a commer- 

 cial variety should have its characters represented by homozygous factors 

 in order that a stable, uniform commercial variety will give expected 

 results under varying growing conditions. 



Cold Resistance in Sweet Corn in its Relation to Quality, Size and Earli- 

 ness. (V. A. Tiedjens). As a result of selecting from 600 ears of sweet 

 corn on the basis of their ability to germinate at low temperatures for 

 two years, one selection from the Whipples' Yellow variety has been 

 saved for further testing. A cross between this selection and a very 

 early Canadian sweet corn was made. The first generation seed is being 

 grown in the greenhouse during the winter months with the use of electric 

 light. This hybrid material will be germinated at a low temperature and 

 selections will be made combining low temperature effects with other 

 desirable characters, toward the production of a large, yellow, early variety 

 that will grow under unfavorable weather conditions. 



