[The effect of different concentrations of indoleacetic acid paste on the transport of (32)P in decapitated pea epicotyls].

Either a 0.25% or a 0.007% IAA paste was smeared on the apical cut surface of decapitated pea epicotyls and simultaneously (32)P was added to the roots. When subsequently the radioactivity of the apical segment of the epicotyls was measured at different time intervals following the addition of (32)P, no significant differences between the effect of 0.25 and 0.007% IAA paste on (32)P transport were found. Because the 0.25% IAA paste completely retards the growth of cotylary buds whereas the 0.007% paste supports this growth, it might appear that the effect of 0.25% IAA paste on the transport of nutrient substances plays a decisive role in the apical dominance. More probably 0.25% IAA paste imitates the apical dominance only by means of its toxic effect, which, however, requires a detailed investigation.