58 MASS. EXPERIMENT STATION BULLETIN 315 



DEPARTMENT OF FLORICULTURE 

 Clark L. Thayer in Charge 



Breeding Snapdragons for Varietal Improvement and Disease Resistance. 



(Harold E. White, Waltham.) Breeding and selection work is being continued 

 with strains now in theF 5 generation. Some ten to fifteen strains of theF 4 gen- 

 eration were grown in the field during the summer, for resistance under field 

 conditions; and, while many of the lines have continued to segregate for resistance, 

 two strains have been selected which are uniformly resistant to rust. These 

 strains are yellow and wh'te flowered types which have bred true for color for 

 three generations. During the past season both strains were tested under green- 

 house and field conditions at the University of Michigan by Dr. E. B. Mains, 

 where they were found to be uniformly resistant to rust. 



Further breeding and selection work will be carried on to develop 100 percent 

 rust resistant strains in other flower colors. 



Propagation Studies on Geraniums. (Harold E. White, Waltham.) Short 

 cuttings, four to five nodes in length, rooted 10 to 20 percent better than long 

 cuttings of six to eight nodes. On six- to eight-node cuttings the rooting response 

 was in favor of the cut being made through or below the node, whereas in the 

 case of four- to five-node cuttings the rooting response was good irrespective of 

 the location of the cut. 



Sand and peat as a rooting medium was 10 to 15 percent better than sand 

 only. A mixture of three-fourths sand and one-fourth German peat was found 

 to be the best rooting medium. Soaking the cuttings for one hour in potassium 

 permanganate solution, one ounce to five gallons of water, prior to placing the 

 cuttings in the medium, gave more favorable results than treating the medium 

 with potassium permanganate solution, one ounce to two gallons of water, applied 

 at the rate of one pint per square foot. 



Starch was found to be much more abundant near the nodes on soft-wood cut- 

 tings than between the nodes. Less starch was found to have accumulated at the 

 nodes in cuttings of older wood. 



Study of the Effect of Plant Nutrients, Soil Reaction, and Light on Gardenias. 



(Harold E. White, Waltham.) A definite growth response in gardenias was ob- 

 served when nitrogen and phosphorus were used in increasing ratios. The response 

 was more pronounced in sand than soil, particularly with phosphorus, due to the 

 probable high degree of fixation of the soil over sand. Increasing amounts of 

 potash had no visible effect on growth either in soil or in sand, which would 

 indicate a low potash requirement for gardenias. Definite growth response to 

 nitrogen and phosphorus in the soil was manifest only after the higher planes 

 were reached, chiefly with phosphorus. 



Low nitrogen was indicated by uniform chlorosis of the foliage and dwarfing 

 of the plants. Interveinal chlorosis was severe on plants fed with calcium nitrate 

 as a source of nitrogen and plants showing interveinal chlorosis became green 

 again after being sprayed with a solution of iron sulfate. Plants that received 

 nitrogen from an ammonia source showed less interveinal chlorosis. 



On the basis of soil pH studies it would seem that soil reaction alone is not a 

 safe basis on which to judge the possibility of interveinal chlorosis occurring on 

 gardenia plants, since experimentally chlorosis appeared on plants when thepH 

 readings with a potentiometer ranged from pH 5.0 to 6.1. 



From the data obtained it appears that gardenias require more iron for normal 



