Vase Life of Cut Rose Flowers Harvested at Different Months and Treated with Poly( 2 -Hydroxypropyldimethylammonium Chloride)

Mem. School. B.O.S.T. Kinki University No.7: 46"""'52 (2000) 46 Vase Life of Cut Rose Flowers Harvested at Different Months and Treated with Poly( 2 Hydroxypropyldimethylammonium Chloride) Hidemi Izumi 1, Hisajiro Yukinaga 1 and Miho Hanafusa 2 Abstract 'Asami Red' roses, harvested at different months of the year, were placed in 250 mg L 1 poly ( 2 hydroxypropyldimethylammonium chloride) ( PHPAC) solution or in water as the control and held at 4 C for 24 h. They were then transferred to water at 20 C and held for 6 or 7 days. Bentneck of control roses was greater with those harvested in July or October than in Mayor December. PHPAC reduced the occurrence and degree of bentneck, and the reduction was the greatest with roses harvested in July. Rates of water uptake and transpiration increased initially and then decreased, with the decrease being greater with control roses. Hydraulic conductance in the basal 3 cm segments of control rose stems decreased during holding and PHP AC retarded the decrease. PHPAC reduced the respiration rates of cut roses. These results indicate that PHPAC suppressed bentneck mainly by maintaining a balance between water uptake and transpiration. Introduction Cut rose flowers have limited longevity due to wilting of flowers and bending of the neck. Wilting results from water deficit, may be caused by bacterial occlusion in the xylem during vase life or nonbacterial blockage during dry storage (1). Bentneck occurs not only by the reduction of water uptake due to the blockage, but also by water stress caused by an elevated transpiration rate (2, 3) and competition for water between leaves and petals (3, 4). The occlusion development during vase life can be prevented by antimicrobial treatments (5, 6, 7), while the occlusion related to dry storage can be prevented by surfactant treatments (8, 9). Quaternary ammonium compounds such as Physan20 and poly ( 2 hydroxypropyldimethylammonium chloride) (PHPAC) have been reported to have antimicrobial and surfactant properties (10). Physan20 increased the vase life of China asters by reducing the microorganisms that caused stem plugging (11). PHPAC, which initially was known by the trial name 2 hydroxy 3 ionen chloride polymer (HICP), extends the vase life of cut rose flowers by inhibiting development of vascular occlusions, but does not decrease the number of bacteria in the lower segment of the flower stem (12). We have observed similar results on the bacterial number in the basal 3 cm of rose stems (13). There is a large seasonal variation in the vase life and number of days until occurrence of bentneck (14). Sensitivity of cut roses to bentneck has been 1. Department of Biotechnological Sciences, Kinki University, Wakayama 6496493, Japan 2. Yokohama Research Center, Mitsubishi Chemical Corporation, Yokohama 2278502, Japan

reported to be affected by environmental factors. Vase life of roses grown in Northern countries like Norway, where there are poor light conditions in winter, increased when the supplementary irradiation level was increased during growing (4). The vase life of cut rose flowers in Japan has been shown to be shorter at higher temperatures in the range from 5 C to 35 C during vase life (15, 16). Effectiveness of pretreatment solution to control bentneck and vase life may differ with time of harvest. Our objective was to determine the effects of PHP AC on the occurrence of bentneck of cut roses harvested at different months of the year and on water uptake and transpiration rates, hydraulic conductance, and respiration rate of cut roses. Materials and Methods Flowering 'Asami Red' roses, trade name Rote Rose, were obtained from a commercial grower in Wakayama at May, July, October and December. After harvest, the flowers were transported dry to the laboratory within 30 min. The stems were cut to a length of 50 cm and all leaves except for the 3 leaves with 5 leaflets each were removed. Roses were placed in 250 mgl I PHPAC solution (Mitsubishi Chemical Co., Tokyo) or in tap water as the control at 4 C in darkness for 24 h. Then they were packed in cardboard boxes lined with newspaper at 20 C for 20 h to simulate dry transportation conditions. Ten stems were placed in each 10 L plastic container with 2 L tap water for measurements of time to bentneck, hydraulic conductance, or respiration rate, and 2 stems in each 3 L container with 1 L tap water for transpiration and water uptake measurements. They were held at 20 C, 75 % RH and 10 11 mol m 2 seci irradiance from coolwhite fluorescence lamps for 6 or 7 days. Bentneck of 10 stems of each treatment was ratea on a scale of 0 to 3 with o = normal and 3 = bending perpendicularly. The two flowers and 3 L containers with or without the flowers were weighed each day to calculate the rates of transpiration and water uptake per 100 g fresh weight. Ten stems were used for each treatment. Hydraulic conductance in the basal 3 cm segments of 5 stems from each treatment that were in the 10 L containers was determined according to the modified method of van Doorn et al. (17). The segments were inserted into tygon tubes and then connected to a 130 cm head pressure of sterilized distilled water 03 KPa). After 1 h, fluid exuding out of the stem was collected in a plastic tube. The flow rate was then determined by weighing the tube after 1 h and expressed as I1Lmm 2 min 1 To determine CO 2 production rate, the 3.5 L container with the 3 stems was sealed for 2 h, and a 1 ml gas sample was removed from the container and measured with gas chromatograph (model GC 8 AIT; Shimadzu, Kyoto) equipped with a thermal conductivity detector. Nine stems were used for each treatment. Results and Discussion Bentneck of control roses occurred on day 4, 2, 3 and 4 with stems harvested in May, July, October and December, respectively (Fig. 1). The degree 47

48 Memoirs of The School of B.O.S.T. of Kinki University No. 7 (2000) of bentneck of control roses was greater with those harvested in July or October than in Mayor December. This is also observed by the commercial growers. Uda et al. (15) reported that transpiration of roses held at higher temperatures exceeded water uptake more than those held at lower temperatures. In our study, temperature was high during July and October, which may have caused water deficit and consequently accelerating the occurrence and development of bentneck. 2.0 May o Control PHPAC July 2.5 2.0 1.5 1.5 Q) h o U [fj 1.0 0.5 0.0 NS NS NS NS ** ** ** ** NS ** ** ** ** ** ** 1.0 0.5 0.0 December 2.5 2.0 1.5 1.0 0.5 0.0 ~ NS NS NS ** ** ** ** ** I I NS NS NS NS ** ** ** * 0.0 o 2 4 6 802 4 6 Days of holding at 20 C 8 Fig. 1. Score of bentneck on roses harvested in May, July, October and December and held in water at 20 C for 6 or 7 days following PHP AC treatment. Vertical lines represent SE. SE bars were not shown when masked by the graph symbol. NS, *, * * Nonsignificant, significant at P<0.05 or 0.01, respectively. PHPAC reduced the occurrence and d~gree of bentneck and the relative reduction compared to the control stems was the greatest with roses harvested in July, which was > October > May > December (Fig. 1). The relative effectiveness of PHP AC was greater for roses having a large amount of bentneck, which was during the months of high temperature. This finding on different effect with temperature during growth is similar to findings during the vase life by Ichimura and Ueyama (1'8), who reported that treatment with

aluminum sulfate, an effective germicide for vase solutions, had a relatively negligible effect on vase life when held at 20 C, but a pronounced effect when held at 25 C. Since the effects of PHP AC on water uptake and transpiration rates, hydraulic conductance and respiration rate were similar among the roses harvested at 4 different months, only the results of roses harvested at October are presented. Rates of water uptake and transpiration of cut roses treated with PHPAC increased initially and then decreased after day 3, while those of control roses remained constant for the first 3 days and decreased thereafter (Fig. 2 A and B). The decrease was greater with control roses than with PHPACtreated roses. 60,,, A 50 c I' O) :>. ~ ed 1\ ed "I::J 40 r +' p.,... ' :::! I Ql) 30 t h 0 0) 0 +' Ti ed 20 t ~ 1 10 PHPAC ~~ _ o L...1I_N,S_NILS NS 1. _*..J..*_*.I*.I*_*l..**1 NS NS NS * * ** ** I o,, I 25 rr,.r,..,r.,.,.., 200 r.i.,..r'~~,~~,~.,..,,~ S 5 "5 ed1. ~_.s 0 \..r u :>. NS ~ ~~I_'_I~~~I_~~I_~~ o 2 60..:' 50 c :>.,S ~ 40 '":' 20 h f< l10 ' +' ed... ' '5. I~ 30 c ill 0 c...,,s I' 150 t..c: :::!... ' "I::JI 2 ~1 00 p., tuj S C\l 8 50, B D,, ~~1 ** ** NS NS NS * * o I I 46802 Days of holding at 20 C Fig. 3. Water uptake rate (A), transpiration rate (B), hydraulic conductance in the 3 cm segments of stems (C) and respiration rate (D) of roses harvested in October and held in water at 20 C for 7 days following PHPAC treatment. Vertical lines represent SE. SE bars were not shown when masked by the graph symbol. NS, *, * * Nonsignificant, significant at P<0.05 or 0.01, respectively. 4 9"2 The ratio of uptake/transpiration, calculated by using average rate on each day, ranged from 0.9 to 1.0, except for control samples on day 6 and 7 where there was a ratio of 0.6. With control roses, transpiration exceeded water uptake after day 5, whereas transpiration of PHPACtreated roses was similar to the water 6 49 8

50 Memoirs of The School of B.O.S.T. of Kinki University No. 7 (2000) uptake during holding period. When transpiration was greater than water uptake, a water deficit occurred in the tissue, which was related to a sharp decrease in water potential in the tissue (2). Hu et al. (4) reported that bentneck was observed in 50% of the cut rose flowers when water loss reached nearly 20% of the initial weight and water potentials of petal and leaf became 0.9 and 1.2 MPa, respectively. In this study, PHPAC may have inhibited water stress as reflected by the decline in water potential in the tissue. Hydraulic conductance in the basal 3 cm segments of control rose stems decreased to about 5 % of the initial value by day 3, while those of PHP ACtreated rose stems began to decrease only after day 5 (Fig. 2 C). Retardation of decrease by PHPAC was similar to that observed by Ueyama and Ichimura (12). Van Doorn et al. (8, 9) suggested that surfactants, by reducing surface tension, facilitated entry of water into airfilled lumen of xylem conduits in drystored rose stems. This repaired column continuity and improved water conduction in the xylem vessels. This action probably was responsible for the effect of PHPAC on water uptake and. water balance. Although the pulse treatment with some surfactants such as Tween20 or Tween80 resulted in visible damage on the leaves and in leaf abscission (8), PHPAC did not show any damage to the leaves. PHP AC reduced CO 2 production of cut rose flowers after day 4 with the average reduction being about 30% (Fig. 2 D). PHPAC may have reduced the physiological activity of roses. Since sugars were consumed as respiratory substrates, cut roses treated with PHPAC probably reserved more sugars as compared to control roses. Soluble carbohydrate concentration in petals is an important factor in determining the vase life of roses (16), because sucrose is helpful in reducing stomatal opening and water loss (19). In summary, PHP AC was effective as a nontoxic pretreatment solution to prevent bentneck of cut roses. The effect was greatest on roses harvested in July, when the bentneck was the greatest and the temperature was the highest among the harvest months. This desirable effect of PHPAC was mainly due to the surfactant property in maintaining water balance. Acknowledgment The authors thank Dr. Alley E. Watada for reading the manuscript. References ( 1) van Doorn, W.G. 1997. Water relations of cut flowers. Hort. Rev. 18: 1 85. (2) Mayak, S., A.H. Halevy, S. Sagie, A. BarYoseph and B. Bravdo. 1974. The water balance of cut rose flowers. Physiol. Plant. 31: 1522. ( 3) Zieslin, N., H.C. Kohl, Jr., A.M. Kofranek and A.H. Halevy. 1978. Changes in the water status of cut roses and its relationship to bentneck phenomenon. J. Amer. Soc. Hart. Sci. 103: 176179. (4) Hu, Y., M. Doi and H. Imanishi. 1998. Competitive water relations between leaves and flower bud during transport of cut roses. J. Jpn. Soc. Hart. Sci. 67: 532536.

( 5) Burdett, A.N. 1970. The cause of bent neck in cut roses. J. Amer. Soc. Hort. Sci. 95:427431. ( 6) van Doorn, W.G. and R.R.J. Perik. 1990. Hydroxyquinoline citrate and low ph prevent vascular blockage in stems of cut rose flowers by reducing the number of bacteria. J. Amer. Soc. Hort. Sci. 115:979981. ( 7) van Doorn, W.G., Y. de Witte and R.R.J. Perik. 1990. Effect of antimicrobial compounds on the number of bacteria in stems of cut rose flowers. J. AppI. Bacteriology 68: 117 122. (8) van Doorn, W.G., R.R.J. Perik and P.J.M. Belde. 1993. Effects of surfactants on the longevity of drystored cut flowering stems of rose, Bouvardia, and Astilbe. Postharvest BioI. Technol. 3 :6976. ( 9) van Doorn, W.G., C. Pak and C.J.J. Buddendorf. 1993. Effects of surfactants on the vascular occlusion induced by exposure to air in cut flowering stems of Astilbe, Bouvardia, and Rose. J. Plant Physiol. 141 :251253. (10) Rembaum, A. 1973. Biological activity of ionen polymers. Appl. Polymer Symp. 22:299317. (11) Kofranek, A.M., E. Evans, J. Kubota and D.S. Farnham. 1978. Chemical pretreatments for China asters to increase flower longevity. Florists' Rev. 162 (4206) :26, 7072. (12) Ueyama, S. and K. Ichimura. 1998. Effects of 2 hydroxy 3 ionen chloride polymer on the vase life of cut rose flowers. Postharvest BioI. Technol. 14: 6570. (13) Izumi, H., N. Murakami, M. Hisada and M. Hanafusa. 1997. Incidence of bentneck relates to bacterial population and rate of electrolyte leakage in stems of cut rose flowers. J. Jpn. Soc. Hort. Sci. 66 (Suppl. 1) : 434435. (Jpn.). (14) Fjeld, T., H.R. Gislerod, V. Revhaug and L.M. Mortensen. 1994. Keeping quality of cut roses as affected by high supplementary irradiation. Scientia Hort. 57: 157 164. (15) Uda, A., K. Fukushima and Y. Koyama. 1995. Effects of temperature and light and dark conditions on wilting of cut rose. Bull. Hyogo Pre. Agri. Inst. 43:101106. (Jpn.). (16) Ichimura, K., K. Kojima and R. Goto. 1999. Effects of temperature, 8 hydroxyquinoline sulphate and sucrose on the vase life of cut rose flowers. Postharvest BioI. Technol. 15:3340. (17) van Doorn, W.G., K. Schurer and Y. de Witte. 1989. Role of endogenous bacteria in vascular blockage of cut rose flowers. J. Plant Physiol. 134:375 381. (18) Ichimura, K. and S. Ueyama. 1998. Effects of temperature and application of aluminum sulfate on the postharvest life of cut rose flowers. Bull. NatI. Res. Veg., Ornam. Plants Tea 13:5160. (19) Marousky, F.J. 1969. Vascular blockage, water absorption, stomatal opening, and respiration of cut 'Better Times' roses treated with 8 hydroxyquinoline citrate and sucrose. J. Amer. Soc. Hort. Sci. 94:223226. 51

52 Memoirs of The School of B.O.S.T. of Kinki University No. 7 (2000) f*rg8~4tijo):i!!~'ito J: u: poly( 2 Hydroxypropyldimethylammonium chloride)!ll1!1! C r{ 7 tj] t) rgo)uj5ri~h~ ~tj ~ 8~M~I:f*rG L t:::{ 7 '7 tj ~ v':j 1'" ~250mg L 1 ilj5ro) poly (2 Hydroxypropyldimethylammonium chloride) (PHPAC) ~i1f. c;c O)xtfi.~ C L L:'71< ~I:~ 4 C~c 248~rs'tWi L t:o ;C O)~&~ 20 C~ 0)71<~l:tWi L L:' 6 cb ~ ~ 'I tj: 7 B rs'i*~ L t:o xtr~izo)/{ 7 ~I: to tj ~«/' r * ':J I] O)~~ 'J:~ 5 f:i cb ~ ~ 'I 'J:12f:1 f*rgj: t) ~ 7 f:i cb ~ ~ 'I 'J:l0f:lf*rGc~iJ~"? t:o PHPAC tj:«/' " * ':J I] O)~~ c t3ht ~flljftjlj L~ ;C O)fLlJflilj~jJ~ 'J: 7 f:i f*rgo)r{ 7 cjl ~:*: ~ ij~"? t:o tj] t) rgo)i1001<s: c ~iis:'j:~ f*~~*]j ~1:~1.JD L L:';C O)~&~~ L t:ij).~ ~~S:'J:xtR~ IZO)"" 7 c:*:~ ij~"? t:o xtr~izo)/{ 7 0)tJ] t) DiJ~ iq 3 cm 0)~tiB0)71<jj~'t~'J:f*~CP ~I:~~ L~ PHPAC 'J:~~~jJIiQ*t:o PHPAC 'J:""7tJ]t)rGO)II g&s:~flljftjijlt:o c.tliqo)~~ 'J:~ PHPAC ij{±~1:g&71< c ~iio)/{ 7 /' A ~f*'"j C. c ~I: J: "? L:' ~ «/'" * ':J I] ~trnftjlj L t: c. C ~~ L L:'~'I ~o