• Applied Biological Chemistry
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• v.42 no.4
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• pp.288-292
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• 1999

It was previously reported that cobalt(II) effectively suppresses the postharvest gravitropic response of snapdragon (Antirrhinum majus L.) (Kim et al. (1997) Agric. Chem. and Biotechnol. 40, 567-571). In this study, several factors affecting the suppression of the gravitropic response by cobalt ion were examined. When flower stalks of snapdragon were pretreated with several different cobalt salts, cobalt nitrate turned out to be the most effective not only in reducing the response but also in preserving the flower quality. We also tested the effects of various detergents which were added to cobalt(II) solution, finding that Tween-40 was the best among the tested with respect to the effectiveness as well as the flower quality. Based on these results, we optimized a protocol for the chemical treatment; that is, a suppressor solution containing 10 mM $CO(NO_3)_2$ and 0.05% Tween-40 was directly sprayed on the gravitropically sensitive region of cut flowers of snapdragon. The suppressor treatment gave rise to a significantly improved results when the flower stalks were stored at a lower temperature after the chemical treatment.

• Applied Biological Chemistry
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• v.40 no.6
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• pp.567-571
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• 1997

Numbers of chemical agents which have been shown to inhibit either auxin signal transduction pathway or ethylene formation in plant cells were applied to cut flower stems of snapdragon (Antirrhinum majus L.) and their effects on the postharvest gravitropic response were studied. The chemical treatments were done by submerging either the stem base or the top part of cut flower, which involves the gravistimulus-sensitive region, for 1 h at $25^{\circ}C$. When the chemicals were supplied from the cut stem base, the gravitropic upward bending of flower stalks kept horizontally after the treatments with 20 mM CDTA or 10 mM $CoCl_2$ was comparable to that of the untreated control, but o-vanadate showed a certain degree of effectiveness for suppressing the bending response. In contrast, the direct application of those agents to the gravitropically sensitive region of cut flowers in the presence of 0.01% Triton X-100 resulted in a substantial reduction of the gravitropic response. In the case of 20 mM $CoCl_2$ treatment, almost total elimination of gravitropism without any significant deterioration of flower quality was observed. The results indicate the possibility of preparation of a protocol involving $CoCl_2$ and a proper surfactant for commercial use to suppress the gravitropic response of cut flowers during postharvest storage and transportation.