Comparative molecular field analysis (CoMFA) method was applied to a set of fluorine-containing compounds to study the relationship between their structure and the anti-gibberella activity. The results show that the contributions of steric and electrostatic fields to the activity are 90.3% and 9.7%, respectively. This means that the steric influence plays a dominant role for the investigated compounds. The relation coefficient (r^2) of non-cross validation for the model established by the study is 0.991, its F value is 297.524 and the standard deviation (S) is 0.015. These values indicate that the model is significant and might have a good predictability. As a consequence, adding bulky groups in certain locations of the parent structure would raise their bioactivity. Accordingly, their predicted activities were found all higher than 0.96.

Key words: WHEAT, FUSARIUM BLIGHT OR SCAB, STRUCTURE ACTIVITY RELATIONSHIP, THREE DIMENSIONAL STRUCTURE, COMPUTER APPLICATIONS