| Abstract
| - Seventeen phenyl-fluorinated analogues of thidiazuron [N-phenyl-N‘-(1,2,3-thiadiazol-5-yl)urea, TDZ]have been prepared and characterized. The effects of each fluorinated urea on growth and qualityof kiwifruits (Actinidia deliciosa) were evaluated by comparison with untreated (control) and TDZ-treated fruits. The results obtained showed a clear dependence of the growth-promoting activity ofthese fluorinated ureas on the pattern and degree of fluorine substitution in the phenyl ring. Themost effective for promoting fruit growth was N-(2,3,5,6-tetrafluorophenyl)-N‘-(1‘,2‘,3‘-thiadiazol-5‘-yl)urea at 25 ppm (at harvest, treated fruits were 58% heavier than untreated ones) followed byN-(3,5-difluorophenyl)-N‘-(1‘,2‘,3‘-thiadiazol-5‘-yl)urea at 10 ppm (50%). Comparatively, TDZ-treatedfruits were 31% (10 ppm) and 38% (25 ppm) heavier than untreated ones. The results also indicatethat the effects of the more active phenyl-fluorinated ureas on some standard quality parameters offruits, for example, percent of fruit dry matter content, soluble solids contents, total titratable acids,shape, and internal structure, are similar to those of TDZ. Quantitative structure−activity relationshipshave been derived for the fruit growth promoting activity of the phenyl-fluorinated analogues of TDZ. Keywords: Actinidia deliciosa; kiwifruit; cytokinin; phenylurea; fluor; fluorinated; thidiazuron; TDZ;fruit-growth activity; plant hormones; QSAR, substituent-induced chemical shifts
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