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The Effect of Pre‐irradiation on the Content of Growth Substances in Xi‐Plants of Brassica oleracea var. acephala. The auxin content of growth stimulated young plants (Brassica oleraceav ar. acephala) of the X2‐generation, originating from X‐ray irradiated seeds (75 kR) was determined. Methanolic extracts were separated on thin‐layer‐chromatograms, which were analyzed by ultra‐violet light and various chemical reactions. Quantitative determinations of growth substances were made using the Avena‐coleoptile‐cylinder‐test. The following results were obtained: 1. X2‐plants had a higher content of IAN compared with unirradiated control samples; 2. IAAm was detectable in only two out of 40 experiments; 3. Two fluorescent substances were detected: a hydroxycinnarmc acid derivative and a long chained unsatu‐rated ketone or aldehyde, which is still unknown. [ABSTRACT FROM AUTHOR]

Three different amino acid conjugates of the auxin naphthalene-1-acetic acid (NAA)-naphthalene-1-acetyl-L-aspartic acid, naphthalene-1-acetyl-D-aspartic acid, and naphthalene- 1-acetyl-L-glutamic acid - have been prepared and tested for growth stimulation in tobacco callus tissues, sunflower hypocotyls, and wheat coleoptiles. All conjugates show less auxin activities than NAA. The ratios of concentrations for more or less the same growth stimulation are 1:25 to 1:100 and less. Each test tissue grows the least on the D-aspartic acid conjugate. These results lead to the conclusion that growth stimulation by these conjugates has to be an indirect one, probably due to their hydrolysis generating free auxins. It is unknown whether the hydrolysis takes place inside or outside the cells. [ABSTRACT FROM AUTHOR]

Effects of Growth Promoters and Inhibitors on Cambium Activity and Formation of Reaction Wood. — The cambium activity of horizontal bent epicotyls of Aesculus hippocastanum can he stimulated by auxins (2,4-D) or kinetin applied artificially. The effect of kinetin was equal on the upper and lower side of the stem. Applied in high concentration to the upper side 2,4-D acted as inhibitor of cell division on this side hut as promoter on the lower side. TIBA was active at the spot of application only. The formation of reaction wood was influenced remarkably by auxins but only slightly by TIBA or kinetin. The results are discussed in term of the theory of growth substances of Went and Cholodny. [ABSTRACT FROM AUTHOR]

Relationship between cell division and morphogenesis of tissue cultures of Daucus carota. II. Respiration of tissue cultures in relation to cell division. - The relationship between oxygen consumption and cell division activity has been studied in explants of the secondary phloem of the tap root of Daucus carota with respect to the influence of various phytohormones. An inverse correlation was found, i.e. explants with a high cell division activity had a low oxygen consumption and explants with a low cell division activity had a high oxygen consumption. [ABSTRACT FROM AUTHOR]

Relationship between cell division and morphogenesis of tissue cultures of Dnucus carota. I. Observations on rhizogenesis and formation of whole plants. By using a chemically defined medium the conditions for formation of roots and embryos in callus of various tap root parts of domestic Daucus carota forms were investigated and compared. Whole carrot plants capable of generative reproduction were produced from callus a.s well as from cell and tissue suspensions. The influence of various phytohormones on differentiation and cell division activity of explants was studied. A close relationship between cell division activity and differential stains was established and explained as a result of the phytohormone action on the cell division rate. [ABSTRACT FROM AUTHOR]

The outgrowth of buds on decapitated pea plants is stimulated by α-(1-naphthylmethylsulphide) propionic acid (NMSP) applied to the cut surface. The antiauxin α-4-chlorophenoxyisobutyric acid (PCIB) does not show a comparable action. Correlatively inhibited buds, which are stimulated when auxin is applied directly to the inhibited buds, are likewise stimulated by a direct application of NMSP. This stimulation by NMSP is very string if the buds are subjected only to a partial correlative inhibition. Isolated stem sections with two buds (without roots and green leaves) show no bud stimulation by NMSP treatment: but if the same plant parts are subjected to a bud inhibition by an endogenous inhibitor extracted from pea plants. NMSP autagonizes the inhibitor effect and thus becomes stimulating. There is a significant interaction between NMSP and the endogenous Inhibitor. The antiauxin PCIB does not show such an interaction. - All experiments are in concordance with the supposition, that NMSP is a competitive antagonist to an endogenous inhibitor present in pea stems and furnished by roots and green leaves. [ABSTRACT FROM AUTHOR]

The influence of short-time treatments on the cell wall properties of the Avena coleoptile was studied. An auxin-incubation of coleoptile sections for 4 hours under circumstances not allowing any growth produces no visible influence on the cell wall properties. However, in walls of cells, not allowed to grow, the rigidity increases with time with or without an auxin-treatment. This has been proved by demonstration of a diminishing cell wall tensility under either condition. Equal elongation of coleoptile sections can be produced in water without anxin or in mannitol solution with auxin. In both cases the ratio between the elastic and the plastic component of the extension is the same. There is no evidence of any influence of auxin on the diffusion pressure deficit by treatments not exceeding 2 hours. [ABSTRACT FROM AUTHOR]