Synthetic Qrowth'Suhstances in Qrafting 



formed no roots after being planted in a rooting medium. No 

 artificial growth-substance was used, and it is not excluded 

 that a synthetic substance might be useful if it were desired 

 to root grafted cuttings. 



Perhaps the most cogent paper that has appeared so far 

 on the application of artificial growth-substances to grafting is 

 that of Lefevre (1939)- He worked with vines {Vttis vinifera) : 

 scions of Pinot d'Ay on a strain of Berlandieri. He used four 

 methods of application : two modes of spraying, immersion of 

 the whole graft in a solution for 48 hours, and dipping the cut 

 ends, only, for 48 hours. This last procedure seemed to be the 

 best, both as regards production of roots and callus-formation 

 of the union. He tentatively recommends a solution of 10 

 parts of growth-substance per 100,000 of water, and he thinks 

 that for use on grafts indole-acetic acid may be superior to 

 indole-butyric acid. 



The review by Chouard (1939) should be consulted. 



Inhibition and Stimulation of Budding and Flowering. Forcing 

 This is a development likely to have considerable import- 

 ance. There is reason to suppose that much work of a mainly 

 practical tendency is being done to extend and perfect the 

 control of dormancy, and also that the results are being 

 to some extent regarded as trade secrets, so that but little 

 is being published. 



The existence, in terminal buds, of a hormone (auxin) or 

 hormones, affects the growth of lateral shoots, as has been 

 shown by Thimann and Skoog (1933, F) and others. From 

 this knowledge it is not a long step to consideration of an 

 endeavour to control bud-development and flowering by the 

 application of artificial growth-substances. If such control 

 were achieved, it would be an important gain in several 

 fields of horticulture: for example, for retarding flowering, 

 and thus loss of blossom and of fruit, in fruit-growing dis- 

 tricts liable to late frosts; and to the plant exhibitor, who 

 could more accurately time the optimal development of his 

 show material. 



Though it does not directly concern the subject of syn- 



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