F-18 used as tracer to study water uptake and transport imaging of a cowpea plant

We present the water uptake ability of cowpea (Vigna unguliculata Walp) whi ch has been regarded as one of the most drought resistant species among the pulse crops. It has been suggested that in the lower part of the stem, par enchymatous tissue for storing water has been developed for the function of drought resistance. We confirmed that in this tissue, water amount was hig h compared to the other stems by neutron radiography. Then the water uptake manner was measured by positron emitting tracer imaging system (PETIS) usi ng F-18 labeled water produced by a cyclotron. Comparing the water uptake m anner of cowpea plant with that of common bean, cowpea plant was found to m aintain high water uptake activity after drying treatment, suggesting the h igh drought resistant character.