24 

 to 208 g/ha to increase sucrose yield in sugar cane. No routine commer- 

 cial use of gibberel lins in aquatic environments could be found. 



Stuart and Cathey (1961) observed that gibberel lins often induce 

 maximum responses when growth conditions are adversely affected by 

 temperature, nutrition, light or other environmental factors, and postu- 

 lated that under these conditions the synthesis of endogenous gib- 

 berel li ns and gibberellin inhibitors may be retarded permitting the 

 greater response from applied gibberel! ins. The major limiting factors 

 to the use of gibberel lins have been the additional cost, the failure to 

 increase yields of major crops, and the fact that the only method of pro- 

 ducing them is through the culture of the Gibberel! a fungus (Salisbury 

 and Ross, 1978). Stuart and Cathey (1961) stated that future commercial 

 applications will depend upon additional data concerning methods and 

 timing of application and the interaction or synergism with other endo- 

 genous and applied plant growth regulators. Based on this review, this 

 statement still appears to apply to gibberellin technology. 



Effects on Waterhyacinths 



Pieterse et al . (1976) reported that the formation of bulbous or 

 "float" type waterhyaci nth leaves could be inhibited by growing the 

 plants in low concentrations (0.03 mg/1 ) of GA 3 in water under 

 greenhouse conditions. The ratio of petiole length and the greatest 

 circumference was approximately 1.0 at 0.00 mg/1 GA 3 , 4.20 at 0.03 mg/1 

 GS 3 and 12.4 at 1.00 mg/1 GA 3 - The general growth pattern of leaves 

 following treatment with low concentrations of GA3 was characterized as 

 similar to morphological responses of plants growing in dense stands 

 or rooted in the shallow hydrosoil as described by Penfound and Earle 



