Doing a project on thigmotropism for science fair. Need suggestions?

My topic is set but i dont know exactly what i want my experiment to be. I'm thinking about trying to inhibit their ability to respond to touch by spraying them with abscisic acid and seeing what will happen. However, i need an added level of complexity. I plan on doing something like grafting the different parts of the tendrils and looking at them under a microscope. Can someone please help. I'm open to all suggestions so dont hold back.