976 BIOLOGICAL EFFECTS OF RADIATION 



Freesia plants produced from irradiated bulbs showed irregularities 

 in the texture of the leaf, stem, and flower which Morgan (43) described 

 as suggestive of "crepe cloth." Light and dark areas in stem and leaves 

 indicated chlorophyll disturbances. Growth irregularities caused curling 

 and twisting of leaves and stems and splitting and deformities of 

 flowers. 



MORPHOLOGICAL EFFECTS ON FLOWER AND FRUIT DEVELOPMENT 



Moore and Haskins (42) have reported premature flowering of grape- 

 fruit plants from X-rayed seeds. Buds in two plants appeared two 

 months after irradiation. A small but normal flower was produced by 

 one, while the other was imperfectly pigmented. A repetition of this 

 experiment with many controls and treated plants would be necessary 

 before it could be definitely concluded that X-rays produce premature 

 flowering. Genera in which Johnson (22a) has found retarded blossoming 

 include the following: Rhodanthe, Dianthus, Gilia, Nemesia, Statice, 

 Schizanthus, Acroclinium, Helianthus, and Lycopersicon. 



Fasciation of the flower head of sunflower resulting from irradiation 

 in the seedling stage has been reported by Johnson (19). Fusion some- 

 times took place in the involucral region, giving the appearance of twin 

 heads, or occasionally there was forking of the stalk below the involucre, 

 with two or three distinct heads resulting. 



Abnormalities of floral parts, including production of double blossoms, 

 were found (21) to occur in tomato plants which were irradiated three 

 times previous to the blossoming period. If, however, irradiation was 

 given at time of budding, when there had been no previous dose, the 

 buds were abscissed. Later growth might produce blossoms, some of 

 which were normal while others were double or triple. Plants irradiated 

 during their early seedling stages showed delayed fruit development. 

 In plants irradiated with one medium dose just before blossoming, com- 

 plete sterility was present for a time. Later the new growth produced 

 small abnormal fruits on 25 per cent of the plants as compared with 

 100 per cent fruit production of the controls. Fruits which did develop 

 on the irradiated plants had a lack of definite internal pattern. The 

 ])lacenta and core showed abnormal development and there was an almost 

 total absence of seeds. Pockets formed in the pericarp of fruits from 

 irradiated plants were not found in the controls. 



Goodspeed (13) noted that in Nicotiana Langsdorffii all buds of the 

 terminal inflorescence were abscissed immediately after treatment and 

 all the first flowers on the laterals were abnormal. Both abnormal and 

 normal flowers set full capsules of seeds. He suggests that the relation 

 of irradiation to the abscission reaction and factors controlling or 

 modifying it should provide an interesting field for carefully controlled 

 investigation. 



