Do you know the concentrations of ethylene produced by fruit at room temperature? We could maybe calibrate one of the instruments in our lab, a GC-MS, for the detection of ethylene - how easy it would be depends on the concentrations. I know apples and other fruit consume oxygen and produce carbon dioxide and ethylene. Ethylene rapidly accelerates the ripening and deterioration of the fruit. In cold storage facilities they lower the oxygen content of the gas in the room to below 5%. Optimum long-term storage conditions involve oxygen concentrations of ~1.5% by volume, carbon doxide concentrations of~3% by volume and ethylene concentrations below 1 PPM. What kinds of experiments did you have in mind?

That is a tough question. Typically measurements are done using gas chromatography. I don't have much to add to answer one.

How accurate an experiment do you want? Your best bet to directly measure the gas levels would be through Petra Van Koppen.

You could get a rough estimate of the level of ethylene gas by comparing the rot caused by ethylene gas by placing fruit of different types and/or combinations in a container. For instance place an apple in a container with an artichoke and in another container just an artichoke and compare the rotting times. Apples produce more ethylene than artichokes, so an artichokes should rot more rapidly in a container with an apple. I don't know how well it would work but you could try it.