Curvature test, Avena

Several in vitro tests are suitable for the determination of the growth-regulating activity of hormone-type herbicides, among them the straight growth test of wheat or oat, and the pea curvature test. Both methods yield quantitative results of good reproducibility. The Avena test elaborated by Went cannot be used in this case, but the root growth inhibition test is suitable (Audus, 1949 1951). 

In condensing the most important data about synthetic auxins in a short survey, for classification and arrangement we also made use to a certain extent of such a guiding principle, derived from results obtained with a restricted number of tests, viz. avena curvature, avena straight growth and pea testis in aU of which cell elongation is the basis of the growth response. 

Fig. 12. Curvature responses of decapitated avena coleoptiles as a function of auxin concentration. (A) curvature obtained in 90min, auxin applied asymmetrically (standard auxin test). (B) curvature produced in 60 min by symmetrical application of auxin upon succeeding transverse electrical stimulation. Bending occurs towards the positive pole, as sketched187 ...

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