The ability of four growth retardants to inhibit the endogenous growth of Avena first internode sections, as well as the effects of interactions between the retardants and GA3 or IAA on the elongation of the sections have been investigated. The results obtained are summarized in Tables 1 and 2. The normal elongation of the sections is not significantly inhibited by treatments with any of the growth retardants employed, except with high concentrations of AMO-1618 or Phosfon D. The simultaneous treatment of a high concentration of Phosfon D (10-4M) with GA3 or IAA partially reduces the expected elongation, whereas AMO-1618, B-995 and CCC when applied in a analogous treatment have little effect. Phosfon D at a concentration of 10-5 M or 10-6 M and exogenously applied GA3 havea synergistic effect on the elongation of Avena first internode sections. The significance of these results for the understanding of the mode of action of growth retardants is discussed.
1. In the color of flowers of Quamoclit pennata, the genes of pink (mutant), red and white are multiple allelomorphic. 2. While F1-hybrid between red and white shows imcomplete dominance as Nohara has pointed out, between red and pink, or between pink and white, the former shows complete dominance in either case. 3. In the color of stems, between violet and green, violet shows complete dominance. 4. There is a complete linkage relation between the genes of colored-flowers (red and pink) and the violet stems, or between the genes of white flowers and green stems.