44 MASS. EXPERIMENT STATION BULLETIN 436 



DEPARTMENT OF FLORICULTURE 

 Clark L. Thayer in Charge 



Breeding Snapdragons for Vaiiety Improvement and Disease Resistance. 



(Harold E. White, Waltham.) The Helen Tobin snapdragon, a recent introduc- 

 tion of the Waltham Field Station, has been grown by florists in 24 different 

 states, north as far as Bar Harbor, Maine, and south as far as Texas and Florida, 

 and requests for seed for trial have been received from foreign countries. Many 

 growers reported this variety as excellent in performance and regarded it as 

 unusual in size, color of flowers, and habit of growth, and several reported it as 

 an excellent variety for their locality. 



As with any new variety of plant material, certain characters need to be im- 

 proved. Therefore, commercial winter-flowering varieties of snapdragon have 

 been crossed with Helen Tobin to obtain a wider range of flower colors. A seed- 

 ling mutation of Helen Tobin, which is of a darker pink color, gives promise of 

 improvement over the present variety and is being selected for further trial. 

 Seed stocks of a number of first generation hybrids of snapdragons and unnamed 

 selfed lines are being increased so that more extensive trials can be made to de- 

 termine their adaptability for commercial use. 



Disease Resistance and Heredity of Carnations. (Harold E. White, Waltham.) 

 Hybridizing of commercial varieties of carnations is being continued. To date, 

 seed production from crosses has been very low; hence large populations from 

 individual crosses, sufficient for a thorough study of disease resistance, have not 

 been obtained. Selections have been made from a number of seedlings from 

 previous crosses, but these do not offer enough variability for reliable conclusions. 

 Cultural treatments and methods of inducing more abundant seed production 

 from carnation plants are being investigated. 



Subirrigation Methods of Watering Carnations. (Harold E. White, Waltham.) 

 The four raised concrete V-bottom benches and two ground beds, which were 

 constructed at the Waltharh Field Station in 1945 for subirrigation studies on 

 florists' crops, were operated with carnations. Half the benches and beds were 

 subirrigated and the remainder were top-watered in the customary manner. 

 The plants made excellent growth under both systems. During the early fall, 

 plants in the subirrigated benches appeared to be somewhat more advanced in 

 growth than the top-watered; but as the season progressed, this difference became 

 less perceptible. 



The number of blossoms cut from subirrigated and top-watered plants was 

 not significantly different. Keeping quality, size of flowers, and length of stems 

 were equally good. Frequency of watering was reduced 50 percent by subirriga- 

 tion methods as compared to the practice of top watering. 



The chief advantage of subirrigation over surface watering is the reduction in 

 frequency of watering, which under greenhouse conditions is a considerable item 

 of expense in growing crops. Other important features are more uniform moisture 

 conditions, better aeration of soils, conservation of plant food elements, and less 

 danger from air-borne fungous diseases. 



Subirrigation methods of watering greenhouse crops by flooding, measured 

 injection of given quantities, constant water level, and automatic regulation are 

 worthy of any grower's consideration. One system may be better adapted for 

 one grower's needs than another, but there is plenty of opportunity for modi- 

 fication of existing methods. Automatic regulation and constant water level 

 methods of watering are being put into operation for observation. 



