Recent Work with Cuttings 



Results with indole-acetic acid (about 0005 per cent, 

 solution for about 36 hours) : 50 to 100 per cent, rooting with 

 16 out of 24 trials on 18 species. No root-formation with 

 Pinus sylvestris and Thuja occidentalis 6-7 years old, but 92 per 

 cent, of Thuja cuttings rooted if taken from trees 20 years old. 

 In general, the treatment gave (i) greater percentage of root- 

 ing; (2) greater root system, especially pronounced with Acer 

 dasicarpum and Ribes rubrum — most cuttings apparently 

 leafless at the start; (3) earlier rooting — mostly 2-6 days' gain, 

 but up to 16 days with Thuja occidentalis of age not stated. 

 Most cuttings were made in summer. Populus alba showed no 

 significant difference in the behaviour of winter and summer 

 cuttings, but otherwise the data were insufficient for forming 

 an opinion as to the advantage of taking winter or summer 

 cuttings. Treatment was 12-36 hours for summer cuttings; 

 20-48 hours for winter cuttings. 



Phenyl-acetic and phenyl-propionic acids behaved similarly 

 to indole-acetic acid, but had a less pronounced effect. 

 Summer and winter cuttings of Populus alba and Ribes rubrum 

 responded readily to the phenyl compounds, but other species 

 did not. (This author is almost the only one who has tested 

 the rooting effect of phenyl-propionic acid.) 



a-naphthyl-acetic acid acted similarly to indole-acetic acid 

 on Populus alba, Quercus pedunculatus, and Ribes aurea (the 

 last, however, not having been treated with indole-acetic 

 acid), but had no effect on Larix sibirica: on which indole- 

 acetic acid caused roots to form on 26 per cent, of not-woody 

 cuttings and on 6 per cent, of woody. 



No satisfactory theory was advanced to account for the 

 difference in responses. Komisarov refers to his 1935 work 

 with Salix caprea and S. cinerea, wherein he obtained 40-70 

 per cent, better rooting after treatment with urine, and maize 

 flour "auxins". 



A modified treatment of cuttings has been announced by 

 Amlong (1938). He placed vine cuttings iyitis vinifera) in a 

 warm bath for 24 hours, before transferring them to aerated 

 tap water, in which they were kept five weeks. The maximum 

 number of roots thus produced without any artificial growth- 



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