Tobacco(Nicotiana tabacumL. ‘X-73’) callus tissue cultures were used in a bioassay system for determining the effect of the following substituted 2,6-dinitroaniline herbicides on growth: trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine); oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide); benefin(N-butyl-N-ethyl-α,α,α-trifluoro-2,6-dinitro-p-toluidine); AC 92390(N-sec-butyl-2,6-dinitro-3,4-xylidine); penoxalin [N-(1-ethylpropyl)-2,6-dinitro-3,4-xylidine]; GS-38946(N-ethyl-N-tetrahydrofurfuryl-4-trifluoromethyl-2,6-dinitroaniline); chlornidine [N,N-di(2-chloroethyl)-4-methyl-2,6-dinitroaniline]; nitralin [4-(methylsulfonyl)2,6-dinitro-N,N-dipropylaniline]; dinitramine(N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine); isopropalin (2,6-dinitro-N,N-dipropylcumidine), and profluralin [N(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine]. The molar concentration required to inhibit fresh weight gain by 50% (I50) was determined by using linear regression analysis on data from a range of five concentrations of each chemical. I50values did not correlate with structural variations or available physical constants. Herbicides listed in order of increasing activity are AC 92390< GD-38946<profluralin = isopropalin<benefin = chlornidine = trifluralin = nitralin<oryzalin = penoxalin < dinitramine. Exogenously applied D-α-tocopherol acetate at 100 times the I50concentrations decreased the inhibition of tissue growth by the herbicides.
Growth and Division of Single Cells of Higher Plants in Vitro