CHAPTER V 



RECENT WORK WITH CUTTINGS 

 [References B on pp. 35-36) 



Applications 



Ordinary woody cuttings 



Effects of natural and synthetic growth-substances apphed 

 to cuttings of a large number of species of shrubs and plants of 

 horticultural importance have been described by Tincker 

 (1936, 1938). Amongst the illustrations given in Tincker's 

 second paper is one showing roots induced on cuttings of 

 Viburnum carlesii, perhaps the most deliciously fragrant- 

 flowered of all shrubs. It is hoped that use of the new syn- 

 thetic growth-substances, by cheapening the cost of plants, 

 will enable this species to be more widely grown. 



Tincker's first paper (1936 a) is a review which may be 

 commended to those interested in the history of the use 

 of growth-substances on plants. His second paper (1936 h) 

 describes his own experiments; he used synthetic phenyl- 

 acetic, indole-acetic, and a-naphthalene-acetic acids, and 

 an extract of urine (the active substance in which was mainly 

 "heteroauxin" — indole-acetic acid), in the form of lanolin 

 pastes of various strengths. He found tomato and Pelar- 

 gonium zonule useful as test plants for the smear preparations. 

 With some woody and "recalcitrant" species the lanolin-paste 

 method of application was ineffective. 



However, aqueous solutions of indole- and a-naphtha- 

 lene-acetic acids were strikingly effective in inducing rooting 

 to occur in cuttings of woody plants such as holly. Tincker's 

 control cuttings, and those that had been treated with the 

 active solutions, were planted in sand, not compost; other- 



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