Dormancy and Storage 269 



esterified auxin at rates such that approximately one gram of auxin 

 is applied per bushel of potatoes. Smith et al (1947) have more re- 

 cently found that auxins applied to the foliage of the plants before 

 harvest will reduce sprouting of root and tuber crops. The methyl 

 ester of naphthaleneacetic acid appears to be effective in this tech- 

 nique. Recent reports indicate that maleic hydrazide can also effectively 

 be used on potatoes, especially as a foliar spray before harvest. The 

 effects of varying concentrations of maleic hydrazide have been re- 

 ported by Paterson et al (1952) as shown in figure 112. It is rather 

 interesting to note that maleic hydrazide, which antagonizes auxin, 

 is more effective in prolonging dormancy at lower temperatures 

 whereas the naphthaleneacetate ester, an auxin, may be less effective 

 at lower temperatures (cf. figures 109 and 112). 



Prolonging dormancy in carrots has been done successfully with 

 the methyl ester of naphthaleneacetic acid dusted onto the roots in 

 storage (Dallyn and Smith, 1952) or by spraying auxins or maleic 

 hydrazide on the foliage before harvest (Wittwer and Sharma, 1950). 



The effective treatment of onions is made more difficult by the 

 protected position of the growing point inside the onion bulb; con- 



500 1000 2500 MG/L 



CONC. OF MALEIC HYDRAZIDE 



Fig. 112. Effects o£ foliar sprays of maleic hydrazide on sprouting of potatoes in 

 subsequent storage at two temperatures (Paterson et al, 1952). 



