Sinking Leaf-Disk Test for Potato Variety Herbicide Tolerance

Abstract

A sinking leaf-disk technique enabled detection of differences among potato (Solanum tuberosumL.) varieties in herbicide tolerance within 24 hr. Susceptibility of varieties to field application of metribuzin [4-amino-6-tert-butyl-3-(methylthio)-as-triazine-5-(4H)-one] was correlated (r = 0.76∗∗) to the number of sunken disks in a metribuzin solution in a growth chamber with continuous light at 30 klux. Varieties that were very tolerant, very susceptible, or intermediate in tolerance to field application of metribuzin were generally in these same categories when evaluated by the sinking leaf-disk technique. Speed of this response was dependent upon herbicide concentration and solution temperature, but the varietal relationships did not change. It was necessary to use leaves of nearly the same age as determined by relative size and position on the plant. Other factors influencing results included plant growth stage, soil moisture, and atmospheric temperature. Results from the sinking leaf-disk test of winter-grown greenhouse plants of the same clones were correlated (r = 0.86∗) to estimated metribuzin injury to field-grown plants. This method, with adequate modification of technique, may have potential use for studying other plant species and other relationships between plants and photosynthesis-inhibiting herbicides.