Plant Qrowth'Suhstances 



A number of trials of indolyl-acetic acid as grafting re- 

 agent and some other new applications are recorded in the 

 papers of Evenari (Schwarz) and Konis (1938). As these were 

 published in a journal that is somewhat difficultly accessible, 

 it may be useful to give here a rather full abstract, though it is 

 not possible to mention every question touched upon in the 

 papers. 



These workers described, in their first paper, experiments 

 with figs, olive, Rosaceae (apple, cherry, pear), and vine; 

 and in their second paper, with several less important species 

 {Hibiscus, Ligustrum, Myrtus, and some ornamental conifers). 

 They used leafless (Part I) and leafed (Part II) cuttings, and 

 applied the growth-substance in three modes: solution, 

 lanolin paste and as actual crystals. They appear to be the 

 first investigators to report the placing of crystalline growth- 

 substance directly in contact with plant tissues. 



These workers report with figs a number of findings 

 regarding the relations between rooting and the possession of 

 terminal buds by cuttings, untreated, and treated apically and 

 basally. Indole-acetic acid applied to olive cuttings led to 

 precocious shedding of leaves ; in olive and Rosaceae, marked 

 formation of callus was induced, but little root-formation. An 

 apple grafting was improved by treatment, but in a pear and a 

 cherry grafting the union of stock and scion was hampered by 

 treatment. 



On all varieties of Vitis vinifera tested, treatment improved 

 rooting all round, though one mode of application was some- 

 times more effective than another, depending on the variety. 

 In all varieties the union of stock and scion (so-called "English 

 graft") was markedly improved by treatment, and in 1938 

 vines were grafted on a large scale at Ein-Harod with an indole- 

 acetic acid treatment. The mode of treatment with growth- 

 substances that was adopted in these two cases is not stated. 



Traub (1938, B) has investigated the transport of natural 

 hormones over the graft union of citron on sweet orange (the 

 former being known to root readily, the latter with difficulty), 

 and concluded that Went's factor for callus formation was 

 transmitted, but not the factor for rooting. The cuttings 



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