Refining Crop Yield Estimates via Isotopic Analysis of Plant Water

College of Letters and Science / Geosciences


This research project will test the hypothesis that the isotopic composition of plant water can be used to accurately estimate crop yield. The rationale for this hypothesis is that transpiration directly affects the isotopic composition of water inside a plant leaf, whereas water inside plant roots reflects the unaltered isotopic composition of the water. By measuring isotopes of water in each of these plant components we will have a more accurate measure of the amount of transpiration, and since transpiration is linearly proportional to yield, a direct estimate of crop yield. The methodology that the student will undertake will be: 1) creating and testing an isotopic reference for use in this research, 2) extracting water from plants and analyzing it for its isotopic composition, and 3) synthesizing, interpreting, and presenting the results.

Tasks and Responsibilities

The student will create a laboratory reference using deoinized water and dried plant material to test the accuracy and precision of the water extraction technique. The student will collect plant tissue samples from farms in Wisconsin at three different sampling time points, and water from these plant tissues will be extracted for isotopic analysis. The student will work with the faculty member to reduce the isotopic data and model the amount of transpiration that occurred for each plant at each sampling time point. Crop yields will then be compared to published records of crop yield in Wisconsin.

Desired Qualifications