Research on the changes in wettability of rice (Oryza sativa.) leaf surfaces at different development stages using the OWRK method.

Background: A good knowledge in wetting behavior of pesticide spray liquid on plant surface is crucial to spray applications. Difference in leaf surface wettability would result in obvious changes in spray wetting behavior. The aim of this paper is to obtain the changes of wettability during different growth periods.

Results: The contact angle (CA) of rice leaf for each liquid increased with rice growth. No significant difference was found between cultivars. The CA was found to be correlated with the polar component of liquid surface tension. The square of the polar component was also found to be highly significant indicating that the relationship between these two properties was not a simple linear one. The surface energy of each plant surface decreased as the plants aged. This was also true of each part of the surface energy. However, no obvious difference on the proportion of the components was found among different cultivars and stages.

Conclusions: The changes in value of CA and surface free energy (SFE) both reflect the changes of the leaf surface wettability, while the SFE value shows better in wettability characterizing. Obvious rice leaf wettability changes were found on different development stages, which may be beneficial for researches in agrochemical sprays wetting and spreading behavior. Factors influencing these alterations were discussed.