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Effects of 2-hydroxy-3-ionene chloride polymer on the vase life of cut rose flowers
Postharvest Biology and Technology 14 (1998) 65 – 70
Effects of 2-hydroxy-3-ionene chloride polymer on the vase life of cut rose flowers Shigefumi Ueyama a,b, Kazuo Ichimura a,* a
National Research Institute of Vegetables, Ornamental Plants and Tea, Ano, Mie, 514 -2392, Japan b Wakayama Horticulture Experiment Center, Shioya, Gobo, Wakayama, 644 -0024, Japan Received 26 November 1997; accepted 20 May 1998
Abstract Cut rose (Rosa hybrida, cv. Sonia) flowers, with or without leaves, were treated with an aqueous solution of 500 mg l − 1 2-hydroxy-3-ionene chloride polymer (HICP), a quaternary ammonium compound, for 4 h, and then transferred to tap water. The pulse treatment with HICP was markedly effective in extending the vase life of cut flowers with leaves, but was ineffective for those without leaves. Irrespective of the presence or absence of leaves, HICP suppressed the reduction in fresh weight of cut flowers with time. The amounts of water uptake and water loss by the cut flowers with leaves decreased until the 4th day after harvest, but both values were higher in cut flowers treated with HICP than in those without treatment. Hydraulic conductance decreased with time, and HICP suppressed this decrease, although the number of bacteria in the lower segment of the flower stem was not decreased by HICP. © 1998 Elsevier Science B.V. All rights reserved. Keywords: Cut flower; 2-Hydroxy-3-ionene chloride polymer; Rosa hybrida; Vase life; Water relations
1. Introduction The vase life of cut rose flowers is often very short due to wilting and bending of the floral axis just below the flower head. The development of these symptoms is considered to be caused by vascular occlusion which inhibits water supply to the flowers (Mayak et al., 1974; De Stigter, 1980; * Corresponding author. Tel.: + 81 592 681331; fax: + 81 592 681339; e-mail: [email protected]
Van Doorn, 1997). The development of this occlusion is correlated with the growth of bacteria at the cut surface and inside the stem (Van Doorn et al., 1989), and addition of bacteria to vase water shortens the vase life of cut rose flowers (Zagory and Reid, 1986; De Witte and Van Doorn, 1988; Clerkx et al., 1989). Thus, vascular occlusion has been considered to be partially due to bacteria, and germicides such as silver nitrate, aluminum sulphate and 8-hydroxyquinoline sulphate have been used in commercial preservatives (Goszczyn-
0925-5214/98/$ - see front matter © 1998 Elsevier Science B.V. All rights reserved. PII S0925-5214(98)00027-1
66
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
ska and Rudnicki, 1988; Uda et al., 1989; Van Doorn et al., 1990). However, pulse treatment with these compounds did not significantly extend the vase life of cut flowers (Uda et al., 1989). Some quaternary ammonium compounds such as Physan-20 have been reported to be effective in extending the vase life of several cut flowers such as Gypsophila and hybrid Limonium (Farnham et al., 1978; Doi and Reid, 1995). Van Doorn and Reid (1992) reported that Physan-20 alone was effective in extending the vase life of cut Gypsophila. Hanafusa (1996) observed that 2-hydroxy-3-ionene chloride polymer (HICP), a quaternary ammonium compound, selected as a growth inhibitor of actinomycetes, was also effective in extending the vase life of cut rose flowers. We report here that HICP was effective in extending the vase life of cut rose flowers by improving their water relations.
abscised. The fresh weight of cut flowers and the amount of water uptake were measured daily. The amount of water loss was calculated by subtracting the increase in fresh weight from the amount of water uptake.
2.2. Determination of hydraulic conductance Hydraulic conductance was measured by a slight modification of the method of Gilman and Steponkus (1972). The basal 5 cm of the stem was inserted into a silicon tube (internal diameter 4 mm). A 130-cm head pressure of water (13 kPa) was applied. The direction of water flow in the stem segments was as in the intact stem. Water that had passed through the segments was collected in tubes connected to the segments for 1 h, after 1 h of equilibration. The flow rate was then determined by measuring the volume of the collected water. Five stem segments were used for each treatment.
2. Materials and methods
2.3. Determination of number of bacteria 2.1. Plant material and HICP treatment Cut rose (Rosa hybrida L. cv. Sonia) flowers were purchased from a commercial grower (Ano, Mie Prefecture) at normal harvest maturity (sepals starting to reflex) and were placed in tap water and used for experiments within 2 h after harvest. The experimental conditions were a temperature of 23°C, 70% relative humidity, and a 12-h photoperiod under 10 mmol · m − 2 · s − 1 irradiance from cool-white fluorescence lamps. Flower stems were trimmed to 40 cm, and all leaves except for the upper three leaves, or all leaves, were removed. Each cut flower was placed in a glass vessel with 10 ml of 500 mg l − 1 2-hydroxy-3-ionene chloride polymer (HICP) (Mitsubishi Chemical Co., Tokyo, Japan) for 4 h. As the control, cut flowers were treated with distilled water. After the treatment, three flowers were transferred to a 500-ml beaker containing 500 ml tap water. Nine flowers were used for each treatment. Vase life was the period from the time of harvest to the time when either the petals lost turgor, the necks were bent, or the petals had
The basal 1-cm stem segments of cut flowers with leaves were wiped with 80% ethanol and 1 g of segments was homogenized in 10 ml of 0.8% sterilized NaCl with an homogenizer (Ultra-turax T25, Ika, Staufen) for 20 s, then filtered through four layers of gauze. The filtrate was diluted 10-, 102-, 103- or 104-fold with sterilized distilled water and an aliquot (100 ml) was inoculated on to LB agar medium (1.2% agar, pH 6.8) that contained 1% bacto-tryptone, 0.5% yeast extract and 0.5% NaCl. After culture at 30°C in darkness for 24 h, the number of colonies was counted.
3. Results
3.1. Effect of HICP on 6ase life and generation of bent-neck In a preliminary experiment, treatment with HICP at 500 mg l − 1 for 4 h (at 23°C) was found to be optimal, and we therefore used this treatment in the experiments reported here. HICP
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
67
Table 1 Effect of HICP on the vase life of cut rose flowers Treatment With leaves Water HICP Without leaves Water HICP
Vase life (days)
4.6a 9.5b 10.0bc 10.6c
Values are means of nine flowers, and those with the same letters are not significantly different (PB0.05) by Duncan’s multiple range test.
markedly extended vase life and inhibited the occurrence of bent-neck of cut rose flowers with leaves (Table 1, Fig. 1). The vase life of cut flowers without leaves was longer than that of cut flowers with leaves, but was not extended by the treatment with HICP. The rate of flower opening was not affected by HICP either with or without leaves (data not shown). It should be noted that HICP did not cause any visible damage to the cut rose flowers. We also examined the effect of aluminum sulphate on the vase life of cut roses.
Fig. 2. Fresh weight of cut flowers with leaves (A) or without leaves (B). Values are means of nine flowers 9 S.E.
When cut roses with leaves were treated with 300 mg l − 1 aluminum sulphate for 4 h, the vase life was extended by 7.4 days (unpublished data).
3.2. Changes in fresh weight and water uptake
Fig. 1. Cut rose flowers treated with distilled water (left) and HICP (right). The photograph was taken 8 days after treatment.
Fresh weight (FW) of flowers with leaves increased until 3 days after harvest, and decreased thereafter (Fig. 2). HICP suppressed this decrease. In the cut flowers without leaves, FW increased until 4 days after harvest, and decreased thereafter, which was also somewhat suppressed by HICP. As shown in Fig. 3, the amount of water uptake by the control flowers with leaves was greater than that of the flowers treated with HICP, at least until 4 days after harvest. Thereafter, the rate of water uptake decreased sharply in the cut flowers not treated with HICP, but less so in the HICP-treated flowers. In cut flowers without leaves, water uptake was only slightly affected by HICP. The changes in the rate of water loss were similar to those of water uptake (Fig. 4).
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3.3. Changes in hydraulic conductance Although hydraulic conductance decreased with time in all cut flowers examined, those treated with HICP had a significantly higher hydraulic conductance throughout the experimental period (Fig. 5).
3.4. Changes in number of bacteria No bacteria were detected either in the basal stems or cut flowers at the day of harvest, or in freshly prepared distilled water or tap water used in the experiment. However, 1 day after harvest, the number of bacteria (number of colonies per g FW) in the base stems was 2.3×106 and 1.1× 105 in control and HICP-treated cut flowers, respectively. However, bacteria increased rapidly thereafter to about 107 in both control and treated stem segments, and remained nearly at the same level, until 7 days after harvest. Fig. 4. Water loss by cut flowers with leaves (A) or without leaves (B). Values are means of three measurements 9S.E.
4. Discussion In the present experiments, a pulse treatment with HICP was markedly effective in extending the vase life of cut rose flowers with leaves (Table
Fig. 3. Water uptake by cut flowers with leaves (A) or without leaves (B). Values are means of three measurements 9 S.E.
Fig. 5. Hydraulic conductance of the basal stem segment from cut flowers with leaves. The inset shows the data from 3 – 7 days after harvest. Values are means of five measurements 9 S.E.
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
1, Fig. 1). This is consistent with the data reported by Hanafusa (1996). The short vase life of cut rose flowers is considered to be caused by impairment of water relations (Van Doorn, 1997). In the present experiments, the vase life of the cut flowers without leaves was longer than that of those with leaves (Table 1), which is in agreement with the reports of Halevy et al. (1974) and Mayak et al. (1974). In the presence of vascular occlusion in the stem, a high rate of transpiration disturbs the water relations, and this may shorten the flower vase life (Van Doorn, 1997). In this study, HICP maintained water uptake of cut roses (Fig. 3) and suppressed the decrease of hydraulic conductance in the flower stem (Fig. 5), suggesting that HICP inhibits development of vascular occlusions. Thus, HICP may improve water relations, leading to extension of the vase life. Vascular occlusion has been correlated with proliferation of bacteria in cut stems (Van Doorn et al., 1989). Several germicides such as aluminum sulphate, silver nitrate and 8-hydroxyquinoline sulphate, which are effective in extending the vase life of cut roses, decrease bacterial growth and reduce vascular occlusion (Van Doorn, 1997). In this study, however, HICP suppressed the decrease of hydraulic conductance in flower stems (Fig. 5), but did not decrease the number of bacteria. This suggests that HICP allows water to bypass the bacteria. Some surfactants such as Tween 20 have also been reported to overcome vascular occlusion of cut flowers without inhibiting bacterial growth (Van Doorn, 1997). These surfactants may decrease surface tension, thereby facilitating entry of water into cut stems. HICP may also possibly act as a surfactant in this way. Water loss from cut flowers with leaves was suppressed by HICP, but that from cut flowers without leaves was not (Fig. 4). Thus, in addition to the inhibition of vascular occlusion, there is a possibility that HICP extends vase life by inhibiting transpiration from leaves. In fact, abscisic acid which inhibits transpiration from leaves (Mansfield and McAinsh, 1995) has been re-
69
ported to extend the vase life of cut roses with leaves (Halevy et al., 1974). Aluminum sulphate, which is widely used in preservative formulations (Goszczynska and Rudnicki, 1988), is also known to inhibit transpiration (Schnabl and Ziegler, 1975; Schnabl, 1976). In our experiment, the vase life of cut roses treated with aluminum sulphate was 7.4 days, which was about 3 days longer that of the control flowers. The effect of HICP on transpiration should therefore be examined in further detail. Although the mechanism of action is not yet clear, HICP markedly extended the vase life of cut rose flowers with leaves. In addition, HICP did not cause any visible damage to the flowers. Thus, HICP might be practically useful in extending the vase life of cut rose flowers.
Acknowledgements We thank M. Hanafusa of Mitsubishi Chemical Co. for the gift of HICP. We also thank Dr F. Fukumoto and M. Sato for their technical advice and K. Matsuda for her helpful assistance.
References Clerkx, A.C.M., Boekestein, A., Put, H.M.C., 1989. Scanning electron microscopy of the stem of cut flowers of Rosa cv. Sonia and Gerbera cv. Fleur. Acta Hortic. 261, 97 – 105. De Stigter, H.C.M., 1980. Water balance of cut and intact Sonia rose plants. Z. Pflanzenphysiol. 99, 131 – 140. De Witte, Y., Van Doorn, W.G., 1988. Identification of bacteria in the vase water of roses, and the effect of the isolated strains on water uptake. Sci. Hortic. 35, 285 – 291. Doi, M., Reid, M.S., 1995. Sucrose improves the postharvest life of cut flowers of a hybrid Limonium. HortScience 30, 1058 – 1060. Farnham, D.S., Kofranek, A.M., Kubota, J., 1978. Bud opening of Gypsophila paniculata L. cv. Perfecta with Physan20. J. Am. Soc. Hort. Sci. 103, 382 – 384. Gilman, K.F., Steponkus, P.L., 1972. Vascular blockage in cut roses. J. Am. Soc. Hort. Sci. 97, 662 – 667. Goszczynska, D.M., Rudnicki, R.M., 1988. Storage of cut flowers. Hort. Rev. 10, 35 – 62. Halevy, A.H., Mayak, S., Tirosh, T., Spiegelstein, H., Kofranek, A.M., 1974. Opposing effects of abscisic acid on senescence of rose flowers. Plant Cell Physiol. 15, 813 – 821.
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S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70 Uda, A., Koyama, Y., Fukushima, K., Nishimura, J., Taniguchi, T., 1989. Extension on the vase life of cut flowers. IV. Effect of pulsing preservative solutions and bacterial numbers in vase and basin water on the vase life of cut rose flowers (in Japanese with English abstract). Bull. Hyogo. Pre. Agric. Inst. (Agriculture) 37, 41 – 46. Van Doorn, W.G., 1997. Water relations of cut flowers. Hort. Rev. 18, 1 – 85. Van Doorn, W.G., Reid, M.S., 1992. Role of ethylene in flower senescence of Gypsophila paniculata L. Postharvest Biol. Technol. 1, 265 – 272. Van Doorn, W.G., Schurer, K., De Witte, Y., 1989. Role of endogenous bacteria in vascular blockage of cut rose flowers. J. Plant Physiol. 134, 375 – 381. Van Doorn, W.G., De Witte, Y., Perik, R.R.J., 1990. Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers. J. Appl. Bacteriol. 68, 117 – 122. Zagory, D., Reid, M.S., 1986. Role of vase solution microorganisms in the life of cut flowers. J. Am. Soc. Hort. Sci. 111, 154 – 158.
Hanafusa, M., 1996. Development of the new preservative PULPIAN, and its pretreatment effect on cut rose flower (in Japanese). J. Jpn. Soc. Hort. Sci. 65 (Suppl. 2), 526– 527. Mansfield, T.A., McAinsh, M.R., 1995. Hormones as regulators of water balance. In: Davies, P.J. (Ed.), Plant Hormones. Kluwer, Dordrecht, pp. 598–616. Mayak, S., Halevy, A.H., Sagie, S., Bar-Yoseph, A., Bravdo, B., 1974. The water balance of cut rose flowers. Physiol. Plant. 31, 15 – 22. Schnabl, H., 1976. Der Einfluss von Aluminiumionen auf den Starkemetabolismus von Vicia faba-Epidermen (The influence of aluminium-ions on starch metabolism of epidermal strips of Vicia faba). Z. Pflanzenphysiol. 77, 167–173. Schnabl, H., Ziegler, H., 1975. Uber die Wirkung von Aluminiumionen auf die Stomatabewegung von Vicia fabaEpidermen (The influence of aluminium ions on the movement of the stomata in Vicia faba-epidermis strips). Z. Pflanzenphysiol. 74, 394–403.
.
Effects of 2-hydroxy-3-ionene chloride polymer on the vase life of cut rose flowers Shigefumi Ueyama a,b, Kazuo Ichimura a,* a
National Research Institute of Vegetables, Ornamental Plants and Tea, Ano, Mie, 514 -2392, Japan b Wakayama Horticulture Experiment Center, Shioya, Gobo, Wakayama, 644 -0024, Japan Received 26 November 1997; accepted 20 May 1998
Abstract Cut rose (Rosa hybrida, cv. Sonia) flowers, with or without leaves, were treated with an aqueous solution of 500 mg l − 1 2-hydroxy-3-ionene chloride polymer (HICP), a quaternary ammonium compound, for 4 h, and then transferred to tap water. The pulse treatment with HICP was markedly effective in extending the vase life of cut flowers with leaves, but was ineffective for those without leaves. Irrespective of the presence or absence of leaves, HICP suppressed the reduction in fresh weight of cut flowers with time. The amounts of water uptake and water loss by the cut flowers with leaves decreased until the 4th day after harvest, but both values were higher in cut flowers treated with HICP than in those without treatment. Hydraulic conductance decreased with time, and HICP suppressed this decrease, although the number of bacteria in the lower segment of the flower stem was not decreased by HICP. © 1998 Elsevier Science B.V. All rights reserved. Keywords: Cut flower; 2-Hydroxy-3-ionene chloride polymer; Rosa hybrida; Vase life; Water relations
1. Introduction The vase life of cut rose flowers is often very short due to wilting and bending of the floral axis just below the flower head. The development of these symptoms is considered to be caused by vascular occlusion which inhibits water supply to the flowers (Mayak et al., 1974; De Stigter, 1980; * Corresponding author. Tel.: + 81 592 681331; fax: + 81 592 681339; e-mail: [email protected]
Van Doorn, 1997). The development of this occlusion is correlated with the growth of bacteria at the cut surface and inside the stem (Van Doorn et al., 1989), and addition of bacteria to vase water shortens the vase life of cut rose flowers (Zagory and Reid, 1986; De Witte and Van Doorn, 1988; Clerkx et al., 1989). Thus, vascular occlusion has been considered to be partially due to bacteria, and germicides such as silver nitrate, aluminum sulphate and 8-hydroxyquinoline sulphate have been used in commercial preservatives (Goszczyn-
0925-5214/98/$ - see front matter © 1998 Elsevier Science B.V. All rights reserved. PII S0925-5214(98)00027-1
66
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
ska and Rudnicki, 1988; Uda et al., 1989; Van Doorn et al., 1990). However, pulse treatment with these compounds did not significantly extend the vase life of cut flowers (Uda et al., 1989). Some quaternary ammonium compounds such as Physan-20 have been reported to be effective in extending the vase life of several cut flowers such as Gypsophila and hybrid Limonium (Farnham et al., 1978; Doi and Reid, 1995). Van Doorn and Reid (1992) reported that Physan-20 alone was effective in extending the vase life of cut Gypsophila. Hanafusa (1996) observed that 2-hydroxy-3-ionene chloride polymer (HICP), a quaternary ammonium compound, selected as a growth inhibitor of actinomycetes, was also effective in extending the vase life of cut rose flowers. We report here that HICP was effective in extending the vase life of cut rose flowers by improving their water relations.
abscised. The fresh weight of cut flowers and the amount of water uptake were measured daily. The amount of water loss was calculated by subtracting the increase in fresh weight from the amount of water uptake.
2.2. Determination of hydraulic conductance Hydraulic conductance was measured by a slight modification of the method of Gilman and Steponkus (1972). The basal 5 cm of the stem was inserted into a silicon tube (internal diameter 4 mm). A 130-cm head pressure of water (13 kPa) was applied. The direction of water flow in the stem segments was as in the intact stem. Water that had passed through the segments was collected in tubes connected to the segments for 1 h, after 1 h of equilibration. The flow rate was then determined by measuring the volume of the collected water. Five stem segments were used for each treatment.
2. Materials and methods
2.3. Determination of number of bacteria 2.1. Plant material and HICP treatment Cut rose (Rosa hybrida L. cv. Sonia) flowers were purchased from a commercial grower (Ano, Mie Prefecture) at normal harvest maturity (sepals starting to reflex) and were placed in tap water and used for experiments within 2 h after harvest. The experimental conditions were a temperature of 23°C, 70% relative humidity, and a 12-h photoperiod under 10 mmol · m − 2 · s − 1 irradiance from cool-white fluorescence lamps. Flower stems were trimmed to 40 cm, and all leaves except for the upper three leaves, or all leaves, were removed. Each cut flower was placed in a glass vessel with 10 ml of 500 mg l − 1 2-hydroxy-3-ionene chloride polymer (HICP) (Mitsubishi Chemical Co., Tokyo, Japan) for 4 h. As the control, cut flowers were treated with distilled water. After the treatment, three flowers were transferred to a 500-ml beaker containing 500 ml tap water. Nine flowers were used for each treatment. Vase life was the period from the time of harvest to the time when either the petals lost turgor, the necks were bent, or the petals had
The basal 1-cm stem segments of cut flowers with leaves were wiped with 80% ethanol and 1 g of segments was homogenized in 10 ml of 0.8% sterilized NaCl with an homogenizer (Ultra-turax T25, Ika, Staufen) for 20 s, then filtered through four layers of gauze. The filtrate was diluted 10-, 102-, 103- or 104-fold with sterilized distilled water and an aliquot (100 ml) was inoculated on to LB agar medium (1.2% agar, pH 6.8) that contained 1% bacto-tryptone, 0.5% yeast extract and 0.5% NaCl. After culture at 30°C in darkness for 24 h, the number of colonies was counted.
3. Results
3.1. Effect of HICP on 6ase life and generation of bent-neck In a preliminary experiment, treatment with HICP at 500 mg l − 1 for 4 h (at 23°C) was found to be optimal, and we therefore used this treatment in the experiments reported here. HICP
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
67
Table 1 Effect of HICP on the vase life of cut rose flowers Treatment With leaves Water HICP Without leaves Water HICP
Vase life (days)
4.6a 9.5b 10.0bc 10.6c
Values are means of nine flowers, and those with the same letters are not significantly different (PB0.05) by Duncan’s multiple range test.
markedly extended vase life and inhibited the occurrence of bent-neck of cut rose flowers with leaves (Table 1, Fig. 1). The vase life of cut flowers without leaves was longer than that of cut flowers with leaves, but was not extended by the treatment with HICP. The rate of flower opening was not affected by HICP either with or without leaves (data not shown). It should be noted that HICP did not cause any visible damage to the cut rose flowers. We also examined the effect of aluminum sulphate on the vase life of cut roses.
Fig. 2. Fresh weight of cut flowers with leaves (A) or without leaves (B). Values are means of nine flowers 9 S.E.
When cut roses with leaves were treated with 300 mg l − 1 aluminum sulphate for 4 h, the vase life was extended by 7.4 days (unpublished data).
3.2. Changes in fresh weight and water uptake
Fig. 1. Cut rose flowers treated with distilled water (left) and HICP (right). The photograph was taken 8 days after treatment.
Fresh weight (FW) of flowers with leaves increased until 3 days after harvest, and decreased thereafter (Fig. 2). HICP suppressed this decrease. In the cut flowers without leaves, FW increased until 4 days after harvest, and decreased thereafter, which was also somewhat suppressed by HICP. As shown in Fig. 3, the amount of water uptake by the control flowers with leaves was greater than that of the flowers treated with HICP, at least until 4 days after harvest. Thereafter, the rate of water uptake decreased sharply in the cut flowers not treated with HICP, but less so in the HICP-treated flowers. In cut flowers without leaves, water uptake was only slightly affected by HICP. The changes in the rate of water loss were similar to those of water uptake (Fig. 4).
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S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
3.3. Changes in hydraulic conductance Although hydraulic conductance decreased with time in all cut flowers examined, those treated with HICP had a significantly higher hydraulic conductance throughout the experimental period (Fig. 5).
3.4. Changes in number of bacteria No bacteria were detected either in the basal stems or cut flowers at the day of harvest, or in freshly prepared distilled water or tap water used in the experiment. However, 1 day after harvest, the number of bacteria (number of colonies per g FW) in the base stems was 2.3×106 and 1.1× 105 in control and HICP-treated cut flowers, respectively. However, bacteria increased rapidly thereafter to about 107 in both control and treated stem segments, and remained nearly at the same level, until 7 days after harvest. Fig. 4. Water loss by cut flowers with leaves (A) or without leaves (B). Values are means of three measurements 9S.E.
4. Discussion In the present experiments, a pulse treatment with HICP was markedly effective in extending the vase life of cut rose flowers with leaves (Table
Fig. 3. Water uptake by cut flowers with leaves (A) or without leaves (B). Values are means of three measurements 9 S.E.
Fig. 5. Hydraulic conductance of the basal stem segment from cut flowers with leaves. The inset shows the data from 3 – 7 days after harvest. Values are means of five measurements 9 S.E.
S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70
1, Fig. 1). This is consistent with the data reported by Hanafusa (1996). The short vase life of cut rose flowers is considered to be caused by impairment of water relations (Van Doorn, 1997). In the present experiments, the vase life of the cut flowers without leaves was longer than that of those with leaves (Table 1), which is in agreement with the reports of Halevy et al. (1974) and Mayak et al. (1974). In the presence of vascular occlusion in the stem, a high rate of transpiration disturbs the water relations, and this may shorten the flower vase life (Van Doorn, 1997). In this study, HICP maintained water uptake of cut roses (Fig. 3) and suppressed the decrease of hydraulic conductance in the flower stem (Fig. 5), suggesting that HICP inhibits development of vascular occlusions. Thus, HICP may improve water relations, leading to extension of the vase life. Vascular occlusion has been correlated with proliferation of bacteria in cut stems (Van Doorn et al., 1989). Several germicides such as aluminum sulphate, silver nitrate and 8-hydroxyquinoline sulphate, which are effective in extending the vase life of cut roses, decrease bacterial growth and reduce vascular occlusion (Van Doorn, 1997). In this study, however, HICP suppressed the decrease of hydraulic conductance in flower stems (Fig. 5), but did not decrease the number of bacteria. This suggests that HICP allows water to bypass the bacteria. Some surfactants such as Tween 20 have also been reported to overcome vascular occlusion of cut flowers without inhibiting bacterial growth (Van Doorn, 1997). These surfactants may decrease surface tension, thereby facilitating entry of water into cut stems. HICP may also possibly act as a surfactant in this way. Water loss from cut flowers with leaves was suppressed by HICP, but that from cut flowers without leaves was not (Fig. 4). Thus, in addition to the inhibition of vascular occlusion, there is a possibility that HICP extends vase life by inhibiting transpiration from leaves. In fact, abscisic acid which inhibits transpiration from leaves (Mansfield and McAinsh, 1995) has been re-
69
ported to extend the vase life of cut roses with leaves (Halevy et al., 1974). Aluminum sulphate, which is widely used in preservative formulations (Goszczynska and Rudnicki, 1988), is also known to inhibit transpiration (Schnabl and Ziegler, 1975; Schnabl, 1976). In our experiment, the vase life of cut roses treated with aluminum sulphate was 7.4 days, which was about 3 days longer that of the control flowers. The effect of HICP on transpiration should therefore be examined in further detail. Although the mechanism of action is not yet clear, HICP markedly extended the vase life of cut rose flowers with leaves. In addition, HICP did not cause any visible damage to the flowers. Thus, HICP might be practically useful in extending the vase life of cut rose flowers.
Acknowledgements We thank M. Hanafusa of Mitsubishi Chemical Co. for the gift of HICP. We also thank Dr F. Fukumoto and M. Sato for their technical advice and K. Matsuda for her helpful assistance.
References Clerkx, A.C.M., Boekestein, A., Put, H.M.C., 1989. Scanning electron microscopy of the stem of cut flowers of Rosa cv. Sonia and Gerbera cv. Fleur. Acta Hortic. 261, 97 – 105. De Stigter, H.C.M., 1980. Water balance of cut and intact Sonia rose plants. Z. Pflanzenphysiol. 99, 131 – 140. De Witte, Y., Van Doorn, W.G., 1988. Identification of bacteria in the vase water of roses, and the effect of the isolated strains on water uptake. Sci. Hortic. 35, 285 – 291. Doi, M., Reid, M.S., 1995. Sucrose improves the postharvest life of cut flowers of a hybrid Limonium. HortScience 30, 1058 – 1060. Farnham, D.S., Kofranek, A.M., Kubota, J., 1978. Bud opening of Gypsophila paniculata L. cv. Perfecta with Physan20. J. Am. Soc. Hort. Sci. 103, 382 – 384. Gilman, K.F., Steponkus, P.L., 1972. Vascular blockage in cut roses. J. Am. Soc. Hort. Sci. 97, 662 – 667. Goszczynska, D.M., Rudnicki, R.M., 1988. Storage of cut flowers. Hort. Rev. 10, 35 – 62. Halevy, A.H., Mayak, S., Tirosh, T., Spiegelstein, H., Kofranek, A.M., 1974. Opposing effects of abscisic acid on senescence of rose flowers. Plant Cell Physiol. 15, 813 – 821.
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S. Ueyama, K. Ichimura / Posthar6est Biology and Technology 14 (1998) 65–70 Uda, A., Koyama, Y., Fukushima, K., Nishimura, J., Taniguchi, T., 1989. Extension on the vase life of cut flowers. IV. Effect of pulsing preservative solutions and bacterial numbers in vase and basin water on the vase life of cut rose flowers (in Japanese with English abstract). Bull. Hyogo. Pre. Agric. Inst. (Agriculture) 37, 41 – 46. Van Doorn, W.G., 1997. Water relations of cut flowers. Hort. Rev. 18, 1 – 85. Van Doorn, W.G., Reid, M.S., 1992. Role of ethylene in flower senescence of Gypsophila paniculata L. Postharvest Biol. Technol. 1, 265 – 272. Van Doorn, W.G., Schurer, K., De Witte, Y., 1989. Role of endogenous bacteria in vascular blockage of cut rose flowers. J. Plant Physiol. 134, 375 – 381. Van Doorn, W.G., De Witte, Y., Perik, R.R.J., 1990. Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers. J. Appl. Bacteriol. 68, 117 – 122. Zagory, D., Reid, M.S., 1986. Role of vase solution microorganisms in the life of cut flowers. J. Am. Soc. Hort. Sci. 111, 154 – 158.
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