Stimulation of Root Growth in Cuttings 115 



Boric add 



A few investigators (Agulhon, 1910, and others) have reported that boric 

 acid stimulates root development in seedlings. Brenchley (1914) found 

 that boric acid has a marked stimulating action on the roots of peas, 

 radishes, wheat, and turnips. 



Phosphates 



It is generally understood in field practice that phosphates have a bene- 

 ficial effect on root growth. This has been reported on by Lawes (1847), 

 Russell (1912), Ames and Boltz (1915), and others. In some preliminary 

 work with seedlings it has been foimd that phosphates, and especially 

 sodium phosphate, markedly increase root growth of flax, alfalfa, and 

 Canada field pea. 



Phosphates are not generally considered as oxygen carriers. Leonid 

 Iwanoff (1910) has found, however, that phosphates increase respiration 

 of living seeds and of seeds killed by treatment with toluol. This was 

 determined by measuring the rate of carbon dioxide production. Dibasic 

 phosphates were more efiicient than monobasic. Nicolaus Iwanoff (1911) 

 found that phosphates have no effect on the respiration of living seeds 

 or living stem tips, but that they do increase the carbon dioxide produc- 

 tion from tissues that have been killed by freezing or by treatment with 

 toluol. He and others have obtained similar results also with yeast. 

 Dibasic phosphates were very efficient, while monobasic phosphates, on 

 the other hand, retarded carbon dioxide production. Iwanoff has shown 

 that the increase in carbon dioxide production brought about by phos- 

 phates is probably due, not to an increase in oxidation, but to an 

 increase in anaerobic splitting. 



From experiments with seedlings the writer has found monobasic phos- 

 phates to be more efficient than dibasic in stimulating root growth. 



Schreiaer, SuUivan, and Reid (1910) state that phosphates markedly 

 increase oxidation by roots and soils, but whether the oxidation in this 

 case is a result of increased root activity, or its cause, is not certain. As 

 far as is indicated by the results of the present investigation, phosphates 

 have no marked effect on root growth of woody cuttings. Tho the writer 

 has Uttle proof as to the mechanism or the fundamentals concerned, he 

 is of the opinion that phosphates as contrasted with nitrates may in some 

 way check the continued growth of tops and thus allow for a greater 



