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  • Author or Editor: L. E. Craker x
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Abstract

Flower fresh wt and diam of petunia (Petunia hybrida Vilmorin, cv. Blue Lagoon) decreased under a 5 day per week ozone treatment of 5 to 7 μl/Hter as compared to controls. Removal of ozone from the plants gaseous environment allowed recovery of the plant with slow return to normal flower development.

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Abstract

Increasing concn of ozone up to 10 to 12 μl/liter decreased anthocyanin content and increased fresh wt but not size in flowers of petunia (Petunia hybrida Vilmorin, cv. Blue Lagoon) and geranium (Pelargonium hortorum Bailey, cv. Red Perfection). Bract anthocyanin increased and bract size decreased in poinsettia (Euphorbia pulcherrima Wildenow, cv. Paul Mikkelson) under the same ozone treatments. Responses were not associated with visible oxidant injury to plant leaves.

Open Access

Abstract

Tomato (Lycopersicon esculentum Mill. cv. Heinz 1350) plants grown in soil with N supplied from (NH4)2SO4 solutions showed a morphological disorder characterized by leaf epinasty. The development of this disorder was accompanied by an increase in the rate of ethylene evolution from whole plants. Ethylene evolution from plants supplied with 0.04 m NH4-N increased to a peak of 112 nl·g−1·hr−1 at ≈2 weeks following the start of fertilization compared to 11 nl·g−1·hr−1 from plants supplied with 0.04 m NO3-N. Fertilization with KC1 in molar equivalency to the supply of NH4-N prevented epinasty and the burst in ethylene evolution. Ethylene evolution from plants of the yellow-green-5 and neglecta-1 mutants did not increase in response to NH4-N fertilization. Potassium concentrations in shoots of ‘Heinz 1350% yellow-green- 5, and neglecta-1 were 2.10, 2.53, and 3.22% (dry weight), respectively, if plants were supplied with NH4-N and no additional K, suggesting that tolerance to NH4 toxicity may be explained in part by differences in K accumulation.

Open Access

Abstract

Over 100 years ago, German investigators reported that defoliation was associated with the proximity of leaking illuminating gas mains (15), and it remained for Neliubov to show that the active component of illuminating gas was ethylene (23). Later, La Rue (20) reported that auxin played a role in abscission because addition of auxin delayed the separation of plant parts. Support for the central role for auxin in abscission stems from the observation that a reduction of auxin content precedes abscission (22). Ethylene was shown to be produced by plant tissue by Gane (14), and increases in the rate of ethylene production during ripening and fruit abscission was shown by Nelson (24) and, during leaf abscission, by Jackson and Osborne (18). A third abscission regulator was introduced when Ohkuma and Addicott (25) demonstrated the presence of abscisic acid (ABA) in rapidly abscissing cotton bolls.

Open Access