WETTABILITY CHARACTERISTICS OF CROP LEAF SURFACES .2.

To evaluate the wettability of plant leaves as a result of interactions between solution and leaf surface, the amount and shape of the retained solution on a specific area of the leaf surface were measured after dipping a leaf into immersion solutions (surface tension: 21.5-63.5 mN.m-1) containing a dye by 1.0% and various surfactants 0.2%, and micro- and macro-structures of the surface were observed. The transition pattern of shape corresponding to the transition of surface tension on the leaf surface was termed as wettability characteristics pattern (WCP) and WCPs of leaves of 39 crops were categorized into three major groups: WCPs I, II and III including seven sub-WCPs. Also, the critical surface tension to wet each leaf surface completely was estimated. It was found that WCP and critical surface tension were specific to each leaf surface and the former was mainly related to the microstructures of leaf surface, especially morphology and distribution of epicuticular waxes and relatively wettable veins. Comparison and evaluation of leaf-surface wettability are possible by WCP on a static basis.