23 

 applications of gibberellins to seeds, soil, or growing plants for the 

 purpose of increasing crop yields generally have not produced 

 encouraging results. In comprehensive field trials by Morgan and Mees 

 (1956), treatment with gibberellic acid failed to increase yields in 

 wheat, potatoes, turnips, carrots, peas, runner beans, lettuce, celery, 

 black currants, kale, and corn. During these trials, vegetative growth 

 of most of the treated plants was stimulated but no increase in crop 

 yield occurred. Marth et al . (1956) conducted a similar series of 

 trials utilizing 42 different species of plants and also reported 

 increases mainly in vegetative growth. Stuart and Cathey (1961) 

 reviewed the applied aspects of gibberellins and reported that gib- 

 berellins are applied to plants cultivated for their flowers in order 

 to (1) replace the requirement for cold temperatures for flowering; 

 (2) accelerate flowering; and (3) enlarge and extend the lasting quality 

 of inflorescences. Current routine commercial uses of gibberellins, as 

 reported by Salisbury and Ross (1978), include increasing the size and 

 distance between Thompson seedless grapes, increasing the rate of the 

 malting processes in breweries, increasing stalk length and 

 crispness of celery, delaying senescence in various fruits, and as an 

 aid in fruit set. Abbott Laboratories, Inc., markets gibberellic acid 

 for the treatment of turf grasses in order to initiate growth and pre- 

 vent color change during cold stress. Abbott Laboratories has also 

 registered gibberellic acid under the brand name Pro-Gibb® (EPA 

 registration numbers 275-20, 275-15, and 275-12) for use on various 

 crops. Rates of application under these registrations vary from 

 1.1 g/ha to obtain uniform bolting and increase lettuce seed production 



