HORTSCIENCE 25(10):1268-1270. 1990. Table 1. Effects of harvest stage and sucrose concentration in the vase solutions on vase life of . All vase solutions contained Postharvest Handling of 200 ppm HQC. Flowers Susan S. Hanl, Abraham H. Halevy2, and Michael S. Reid Department of Environmental Horticulture, University of , Davis, CA 95616 Additional index words. cut flowers, harvesting stage, preservatives, storage, Triteleia laxa Abstract. Vase life of individual flowers of cut brodiaea (Triteleia laxa Benth.) inflores- cences ended 4 days after opening. Best vase life was achieved by harvesting inflores- cences 1 to 2 days before anthesis of the first flower and holding them in a vase solution containing 2% sucrose and 200 ppm 8-hydroxyquinoline citrate (HQC). Such inflores- cences had a display life of 12 days. Decreasing the pH of the vase solution or pulsing inflorescences with 10% sucrose for 16 hours did not increase their longevity. T. laxa flowers pretreated with 10% sucrose overnight could be stored for up to 2 weeks without significant reduction in vase life. Table 2. Effects of sucrose treatments on the vase The commercial production of brodiaea white fluorescent light each day, 60% RH). life of Triteleia laxa. Flowers were held contin- flowers (specifically Triteleia laxa ‘Queen The vase life was considered terminated when uously in various concentrations of sucrose, or Fabiola’) recently has increased markedly, the number of senescent flowers exceeded pulsed in 10% sucrose for 16 hr at room tem- and there is now interest in using other spe- the number of open flowers. perature and then held in distilled water. All cies of the brodiaea complex as cut flowers. Harvest stage and sucrose. The post- solutions contained 200 ppm HQC. The commercial success of any new cut flower harvest life of cut flowers can be greatly af- depends not only on its aesthetic qualities fected by their maturity at harvest. Many and ease of production, but also on its vase flowers are normally harvested at the bud life after normal commercial handling. Op- stage because buds are easier to handle and timal postharvest life of cut flowers is often usually have a longer vase life than open strongly affected by the maturity at harvest, flowers. Previous workers suggested that and may be improved by sucrose pretreat- brodiaea inflorescences should be cut at stages ment and use of suitable vase solutions 4 to 6 (De Hertogh, 1980; Kofranek, 1986). (Halevy and Mayak, 1979, 1981). The suc- Our data show that brodiaea inflorescences cess with which cut flowers can be stored is harvested 1 to 2 days before anthesis of the variable, depending on the (Hard- largest flower bud lasted 4 days longer than enburg et al., 1986). We examined the op- those harvested at the stages previously rec- timal harvest stage for brodiaea flowers, and ommended, regardless of the sucrose con- the effects of biocides, pH, and sucrose con- centration used in the vase solutions (Table centrations in the vase solution on their vase 1). life. We also examined the possibility of long- Brodiaea flowers opened steadily at a rate term storage of harvested brodiaea flowers. of one flower per day during the vase life of materials and vase life evaluation. the inflorescence (Fig. 1), and the first flow- ‘Queen Fabiola’ brodiaea flowers were grown ers had senesced by day 4. The life of the outdoors in Davis, Calif. Inflorescence ma- individual flowers (horizontal distance be- turity was defined on a scale of 0 to 4, de- tween opening and senescence curves in Fig. supply and pulsed application of sucrose on pending on the number of open flowers in 1) was 4 days throughout the vase life, and vase life, eight replicate inflorescences were the inflorescence. One day before the first the life of the inflorescence (day when 50% placed in solutions containing 200 ppm 8- flower opened was defined as Stage 0, of the open flowers were senescent) was 12 hydroxyquinoline citrate (HQC) and 0%, 2%, inflorescence with 1, 2, 3, or 4 open flowers days. 4% or 8% sucrose, or were pulsed overnight was defined- as Stage 1, 2, 3, or 4, respec- To compare the effect of a continuous at room temperature with 10% sucrose and tively. Unless otherwise specified, inflores- cences were harvested from the field when their first flower reached anthesis (Stage 1). The inflorescences were placed individually in sterile polyethylene vases containing ml of vase solution. Their opening and vase life were evaluated in a controlled environ- ment (21C, 12 hr 15 mol·s-l·m-2 cool-

Received for publication 12 Dec. 1988. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regu- lations, this paper therefore must be hereby marked advertisement solely to indicate this fact. 1Present address: Department of Plant and Soil Sciences, French Hall, Univ. of Massachusetts, Amherst, MA 01003. 2Permanent address: Faculty of Agriculture, The Hebrew Univ. of Jerusalem, Rehovot 76-100 Is- Fig. 1. Time course of the opening and senescence of Triteleia laxa flowers in an inflorescence placed rael. in water.

1268 HORTSCIENCE, VOL. 25(10), OCTOBER 1990 sucrose overnight had very little effect on the None of the biocides tested had any sig- opening and vase life of brodiaea inflores- nificant effect on vase life when used in con- cences (Table 2), possibly because gladiolus junction with 2% sucrose (Table 3). Of those flowers have some leaves whose transpira- biocides tested, HQC, the one used in many tion would tend to increase the carbohydrate commercial preservatives, proved to be the accumulated during the pulsing period. best. Phytotoxicity was observed, however, Rate of water uptake. Rates of water up- on scapes placed in solutions containing either

take were monitored continuously using a Physan or AgNO3. Silver nitrate caused total computer connected to the digital output of blackening of the portion of the scape in the an electronic balance (Fisher Scientific Model solution, and we found that Physan, rec- 8301A). A beaker containing water (and ommended for this species by Kofranek covered with a sheet of Parafilm perforated (1986), led to rapid collapse of the immersed in the center) was placed on the balance. An portion of the scape. inflorescence was lightly held in a bench Effects of pH. Low pH in the vase solu- clamp so that its base dipped into the water tion, which has been reported to improve the but did not touch the beaker or the Parafilm. vase life of cut roses (Durkin, 1979), had no The decrease in weight of the beaker was significant effect on the vase life of brodiaea taken as a measure of water uptake by the inflorescences. There were no significant inflorescence. The contribution of different differences in vase life of infloresences that portions of the inflorescence to water uptake were harvested at Stage 2 or 3, then placed was determined by measuring water uptake in vase solutions containing 2% sucrose and then placed in 200 ppm HQC solution with- after removal, first of the flower buds, then 200 ppm HQC whose pH was adjusted to 3, out sucrose. An average of 1.6 ml of the of the peduncles. 4, 5, 6, or 7 with KOH or HCl (data not pulsing solution was taken up by each The typical steady rate of water uptake by shown). The difference between cut roses inflorescence. As in the case of many other a brodiaea inflorescence was 1.8 g H20/g and brodiaea may relate to the absence of flowers (Halevy and Mayak, 1979), contin- fresh weight per day. By sequentially re- leaves in brodiaea inflorescences. The water uous development of small brodiaea flower moving organs from an inflorescence, we uptake of brodiaea inflorescences (12 buds to fully open flowers requires an ex- determined that 60% of the water was taken ml·day -1) is only one-fifth that of rose flow- ternal supply of carbohydrate. More than 50% up by the flower buds (fresh weight basis: ers (Carpenter and Rasmussen, 1973), and it of the buds on brodiaea inflorescences (har- 0.9 g·g-1·day-1), 16% by the peduncles (0.5 is therefore probable that water supply to these -1 -1 flowers is seldom limiting. vested at Stage 0 or 1) placed in water failed g·g-l ·day -l), and 24% by the scape (0.4 to open, even if they were pretreated for 16 g·g ·day ). Effects of storage. The flowering period hr with 10% sucrose (Table 2). The per- Effects of biocides. Inflorescences were for each species of brodiaea is short, and it centage of open flower buds and the vase placed in opening solutions containing 2% would be useful if the inflorescences could life of inflorescences placed in solutions sucrose and a biocide. The biocidal solutions be stored at low temperatures to extend the without sucrose were less than those placed tested were 200 ppm HQC, 100 ppm Physan commercial marketing period (Hardenburg in solutions containing sucrose. The addition (n-alkyl dimethyl benzyl ammonium chlo- et al., 1986). To test how storage affects the of sucrose to the vase solution greatly im- ride-n-alkyl dimethylethylbenzyl ammo- life of brodiaea cut flowers, inflorescences proved flower opening and, consequently, nium chloride), or 50 ppm AgNO3. In harvested from the field were wrapped in vase life. Sucrose at 1% was as effective as addition, the effect of 100 ppm Physan was perforated plastic bags. Some inflorescences higher concentrations in improving the vase tested for flowers whose base was first dipped were pretreated overnight with 10% sucrose life of brodiaea (Table 1). Unlike for gladi- for 10 sec in 1000 ppm AgNO3. There were as described above. They were then stored olus (Mayak et al., 1973), pulsing with 10% five replications per treatment. dry in the bags in darkness at 1C for 2 or 4 weeks. After storage, the inflorescences were placed m solutions containing either 2% or 4% sucrose and 200 ppm HQC. Control inflorescences were placed in the same so- lutions immediately after harvest. The vase life of inflorescences stored for 2 weeks and then placed in a 2% sucrose vase solution was the same as that at harvest, but fewer flower buds opened (Table 4). In- creasing the sucrose concentration in the vase solution to 4% or pretreating the inflores- cences with 10% sucrose before storage sub- stantially improved bud opening of inflores- cences stored for 2 weeks. Small flower buds Table 4. Effects of dry storage and sucrose supplied after cold storage on vase life and opening of (bud length 8 mm) aborted after prolonged Triteleia laxa. All opening solutions contained 200 ppm HQC. Pulse treatments were applied before storage, and increased sucrose concentration in the vase solution had no effect on extend- ing the vase life of long-stored brodiaea inflorescences (Table 4). The slender scapes suggest that brodiaea inflorescences have a relatively small carbohydrate pool in relation to the high respiration rate of their flower buds (average 900 mg/kg fresh weight per hour) and the carbohydrate requirement for the developing buds. This situation may ex- plain the advantageous results of high su- crose application to inflorescences that had been stored for 2 weeks.

HORTSCIENCE, VOL. 25(10), OCTOBER 1990 1269 Respiration rate of brodiaea flowers. vase solution containing 2% sucrose and 200 Halevy, A.H. and S. Mayak. 1981. Senescence Flower buds were harvested and placed in ppm HQC. Brodiaea flowers may be stored and postharvest physiology of cut flowers. II. 25-ml glass vials ventilated (2.4 liter·hr -1) up to 2 weeks without significant reduction Hort. Rev. 3:59–141. with CO -free air. The CO content of the in flower quality if pretreated with 10% su- Han, S. S., A.H. Halevy, and M.S. Reid. 1990. 2 2 The role of ethylene in petal senescence and exit air stream was determined using an ADC crose overnight before storage. ovary growth of Triteleia laxa ‘Queen Fabiola’. infra-red gas analyzer type 225-2B-SS (An- J. Amer. Soc. Hort. Sci. (In press.) alytical Development, Hoddeson, England). Literature Cited Hardenburg, R. E., A.E. Watada, and C.Y. Wang. The respiration rate of young brodiaea Carpenter, W.J. and H.P. Rasmussen. 1973. Water 1986. The commercial storage of fruits, vege- flower buds was very high and decreased uptake rates by cut roses (Rosa hybrida) in light tables, and florist and nursery stocks. U.S. Dept. rapidly until they reached anthesis; that of and dark. J. Amer. Soc. Hort. Sci. 98:309-313. Agr. Hdbk. 66. open flower buds continued to decline, but De Hertogh, A.A. 1980. Bulbous , p. 215- Kofranek, A.M. 1986. Studies on the postharvest at a slower rate, reaching a steady rate 3 days 235. In: R.A. Larson (cd.). Introduction to flor- handling of Triteleia laxa. Acta Hort. 181:231 - after anthesis (Fig. 2). iculture. Academic, New York. 236. Durkin, D. 1979. Effect of millipore filtration, Mayak, S., B. Bravdo, A. Guilli, and A.H. Hal- For maximum vase life, brodiaea inflores- evy. 1973. Improvement of opening of cut gla- cences should be harvested 1 to 2 days be- citric acid, and sucrose on peduncle water po- tential of cut rose flower. J. Amer. Soc. Hort. dioli flowers by pretreatment with high sucrose fore anthesis of the largest flower and Sci. 104:860-863. concentrations. Scientia Hort. 1 :357–365. pretreated with silver thiosulfate to prevent Halevy, A.H. and S. Mayak. 1979. Senscence Veen, H. and S.C. van de Geijn. 1978. Mobility the action of external C2H4 encountered dur- and postharvest physiology of cut flowers. I. and ionic form of silver as related to longevity ing marketing (Veen and van de Geijn, 1978; Hort. Rev. 1:204-236. of cut carnations. Planta 140:93.-96. Han et al., 1990). They should be held in a

HORTSCIENCE 25(10) :127O-1271. 1990. in the F- solution. The purpose of this research was to ex- amine the effectiveness of a calcium nitrate Fluoride Injury to Cut ‘Samantha’ pulse in reducing F- injury to cut roses held in keeping solutions. Calcium pulsing would Roses May Be Reduced by Pulsing be simple and could be performed in com- bination with current pulsing practices. Cal- with Calcium Nitrate cium pulsing would have the advantage of being totally controlled by the producer, thus Caroline H. Pearson-Mires and Virginia I. Lohr assuring the producer of delivering a product Department of Horticulture and Landscape Architecture, Washington that would retain prime quality. State University, Pullman, WA 99164-6414 Cut ‘Samantha’ roses were obtained from a wholesale supplier. When received, flower Additional index words. cut flowers, postharvest quality, Rosa hybrida stems were cut under water to 24 cm and leaves were removed from the lower 16 to Abstract. Cut ‘Samantha’ roses (Rosa hybrids L.) were placed in deionized water or 18 cm of each stem. Initial fresh weight was a 20-mM Ca(N03)2 pulsing solution for 72 hours. Flowers then were held in preservative recorded. Flowers were randomly placed in solutions containing 0 or 4 mg fluoride/liter. Fresh weight gain, solution uptake, degree deionized water or 20 mM Ca(NO3)2. This of flower opening, and flower longevity were reduced in the presence of fluoride in the concentration was selected after a prelimi- holding solution. Visual symptoms of injury and reduced flower quality also were noted nary study using 0, 5, 10, 15, and 20 mM in treatments with fluoride. Pulsing improved fresh weight gain and degree of opening Ca(NO 3)2 pulsing solutions showed no dif- of flowers held in solutions containing fluoride. Pulsing also delayed the onset of visual ferences in fresh weight change, solution up- symptoms of fluoride injury. Water uptake for flowers that were pulsed and exposed take, degree of opening, or visual appearance to fluoride was not different from uptake for flowers exposed to fluoride alone. Flower among flowers in any of the treatments. longevity for roses in all treatments was increased by using the calcium nitrate pulse, Flowers were pulsed in darkness at 4C for but pulsed flowers in fluoride did not survive as long as the control flowers. 72 hr, then removed from the solutions and fresh weight, initial solution weight, degree Several studies have documented the sus- become dissatisfied with the commodity (Lohr of flower opening, and visual observations ceptibility of various cut rose cultivars to in- and Pearson-Mires, 1989, 1990). were recorded (Day 0). Flowers were pulsed jury from fluoride (F-) in keeping solutions Calcium, combined with other chemicals, for 72 hr to ensure complete uptake of the (Lohr and Pearson-Mires, 1989, 1990; has been used to improve postharvest quality calcium nitrate solution. Stems were placed Waters, 1968). Symptoms of soluble F- tox- of many cut flowers and to extend the lon- icity included flower discoloration, petal gevity of some flowers (Halevy and Mayak, margin deterioration, and incomplete flower 1981; Mayak et al., 1978). Pretreatment Table 1. Effect of a calcium nitrate pulse and F- development (Lohr and Pearson-Mires, 1989, containing Ca have been found to be effec- in the keeping solution on flower opening, so- 1990; Waters, 1968). In many cultivars tested, tive in reducing or preventing the expression lution uptake, and longevity of cut ‘Samantha’ injury was so severe that consumers could of atmospheric F- toxicity in geranium (Gar- roses. ret and Chopin, 1982). Fluoride moves Average Total through the transpirational stream in plants degree of solution Longevity Received for publication 13 Nov. 1989. H/LA Pa- and accumulates at leaf and flower surfaces Treatment opening 2 uptake (ml) (days) per no. 89-29. Project no. 0695, College of Ag- and margins (Spierings, 1969). Calcium mi- y riculture and Home Economics Research Center, Control 4.2 ab 29 a 6.8 b grates towards the area of high F- content, Pulse 4.3 a Pullman, WA 99164. Appreciation is expressed to 31 a 7.8 a where it binds with and inhibits the toxic F- 3.6 c 24 b 3.4 d Don Jacobson, Jacobson Greenhouses, Spokane, - Wash., for donating the flowers used in this ex- action of F- (Garret and Chopin, 1982). In Pulse with F 4.0 b 24 b 4.4 c periment. The cost of publishing this paper was preliminary work, we found that visual zOpening on a scale from 1, a bud opened slightly defrayed in part by the payment of page charges. symptoms of injury to cut ‘Sonia’ roses held at the apex, through 7, an open flower with visible Under postal regulation, this paper therefore must in a keeping solution containing 4 mg F-/ stamens. be hereby marked advertisement solely to indicate liter were reduced when the flowers were yMean separation within cohumns by LSD, P = this fact. pulsed with calcium nitrate before placement 0.05.

1270 HORTSCIENCE, VOL. 25(10), OCTOBER 1990