A recessive, nuclear factor for susceptibility to atrazine was defined by C. 0. Grogan et al. (Crop Sci. 3:451, 1963) in inbred line GT112, which was supplied to us in tolerant and susceptible versions by G. E. Scott. Linkage to chromosome 8 (Scott and Grogan, Crop Sci. 9:669, 1969) was defined by wx translocations, using field applications of the herbicide and classifying F2s for healthy vs. dead plants. The recombination percentages were, for wx T8-9d (8L.09), 23 ± 6%; for wx T8-9(6673)(8L.35), less than 25 ± 10% (there were 0 plants in the wx dead class). The factor may be in 8L or 8S. A small test of crosses with TB-8La did not show dead seedlings in a treated field, but the germination was poor. Susceptible material can be grown in pots and can be transplanted to the field when the plants are well established. Susceptible plants have been shown to lack the usual enzyme activity for conjugation of glutathione with atrazine (R. H. Shimabukuro et al., Plant Physiol. 47:10, 1971). The atrazine susceptibility factor has not been assigned a symbol; ats (atrazine susceptible) would seem to be suitable.

E. H. Coe and J. B. Beckett

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