Table 4. Power consumption, water use and cost for a 4-acre container nursery. (25 hp elec. motor and 300 gpm deep well pump), Central Florida. Water Total Hrs. Pumped Month Yr. KWH Used Cost/KWH Operated Mo. Cost (Ac-in) In./Ac/Mo. Jan. 1975 354 6.5tf 16.70 $23.16 11.07 2.76 Feb. 1975 312 6.7^ 14.72 $20.99 9.75 2.43 Mar. 1975 512 6.2tf 24.16 $31.63 16.01 4.00 Apr. 1975 778 6.6^ 36.72 $51.55 24.34 6.08 May 1975 928 6.4^ 43.80 $59.56 29.03 7.25 June 1975 746 6.9^ 35.21 $51.55 23.34 5.83 July 1975 848 5.7^ 40.02 $48.33 26.52 6.63 Aug. 1975 478 6.2tf 22.56 $29.86 14.95 3.73 Sept. 1975 734 5.8<£ 34.64 $42.90 22.96 5.74 Oct. 1975 342 6.5^ 16.14 $22.08 10.69 2.67 Nov. 1975 608 5.7tf 28.69 $34.78 19.01 4.75 Dec. 1975 498 5.9^ 23.50 $29.37 15.57 3.89 Total 1975 7138 6.3tf 336.86 $445.76 223.24 55.81 Table 5. Power consumption, water use and cost for a 4-acre container nursery. (25 hp elec. motor and 300 gpm deep well pump), Central Florida. Water Total Hrs. Pumped Month Yr. KWH Used Cost/KWH Operated Mo. Cost (Ac-in) In./Ac/Mo. Jan. 1976 436 6.0^ 20.57 $26.33 13.63 3.40 Feb. 1976 442 6.1tf 20.86 $26.97 13.82 3.45 Mar. 1976 470 6.1^ 22.18 $28.75 14.70 3.67 Apr. 1976 708 5.8^ 33.41 $41.25 22.14 5.53 May 1976 862 6.4^ 40.68 $50.06 26.96 6.74 June 1976 400 6.5^ 18.87 $25.97 12.51 3.13 J«iy 1976 722 5.9^ 34.07 $42.44 22.58 5.65 Total 1976 4,040 6.1^ 190.64 $241.77 126.34 31.58 (7 mo.) The probable reason for high water use for the 17-acre Summary nursery is that it is on a high hill, subject to high winds and From these data, a study of 3 nurseries shows that daily extremely high temperatures, whereas, the 4-acre nursery is gross water applications by commercial growers vary from on low land on the southeast corner of a lake, and they use as low as 0.15-inch to as high as 0.30-inch per day. Many more spot (hand hose) watering. Irrigation for the 13-acre researchers feel that many nurseries often over-water. nursery is completely automated and operates at night. Further research will need to be carried out before a precise determination can be made. Proc. Fla. State Hort. Soc. 89:313-315. 1976. EFFECT OF INTERRUPTED LIGHTING ON PEDUNCLE LENGTH AND SPRAY FORMATION OF CHRYSANTHEMUM MORIFOLIUM RAMAT B. TjIA AND M. GLASSER grown under interrupted lighting, which is the regulation Department of Ornamental Horticulture, short and long photoperiods during flower initiation, resulted University of Florida, in longer peduncles, open sprays and delayed flower ma- Gainesville, FL 32611 turity. Ten, 12 and 14 short photoperiods followed by 8 or 10 long photoperiods increased peduncle length significantly. Additional index words. Photoperiod. Production of spray chrysanthemums in Florida is done Abstract. Spray chrysanthemum cultivars, especially 'Ice mostly in open fields under full sun or partial shade. Plants berg' which is widely grown in South Florida, tend to de thus grown with no controls of temperatures and light in velop shorter peduncles compared to northern and South tensity are inferior in quality compared to plants grown American grown chrysanthemums. Retail florists prefer spray under conditions where these variables are controlled. Early chrysanthemums with relatively long peduncles to facilitate and late in the season (October and May) when tempera individual flower usage in arrangements. Chrysanthemum tures are frequently high and when flowering time of chry santhemum is controlled by night light breaks, the size of iFlorida Agricultural Experiment Stations Journal Series No. 253. flower, internode length and rate of flowering vary con- Proc. Fla. State Hort. Soc. 89: 1976. 313 siderably (1, 3, 9). Flowers with highest quality are gen per plant. Short days were interrupted with 8 to 10 long erally produced in the winter and early spring, in Florida days by night breaks as previously described following 10, 12 and in spring and fall in Northern states. Cool night tem or 14 consecutive short days. Each treatment and a control, peratures and adequate light levels at these times probably which was subjected to continuous short days consisted of 4 are responsible for superior quality of flowers (1, 3, 5). Short plants, were replicated 3 times, randomly assigned within peduncles on spray flowers are prevalent early and late in each replicate and placed crosswise, 5 pots across a 150 cm the season mostly due to high light intensities and high wide bench. Flowering date was recorded when the first night temperatures. Short peduncles and, consequently laterals were fully open at which time height was measured stubby spray appearance decreases the marketability of such from pot rim to the highest lateral flower buds. Terminal sprays. Retailers prefer relatively long peduncles to facilitate flowers, second, third, etc. lateral flowers were measured individual usage of flowers in arrangements for retail trade. from the main stem to the base of flower heads. Attempts to increase peduncle length and control spray formation is not a new idea since Post (6, 7, 8) spearheaded Result and Discussion investigations along these lines in the early forties. He re These data utilizing the same general schedule by Post, ported (8) that length of peduncle could be increased by (7, 8) of 10 to 14 long days (LD) followed by 8 to 10 days interrupted lighting and peduncle length was dependent on short days (SD) resulted in good quality sprays and signif the number of long photoperiods which followed initial icantly increased peduncle length. There was no consistent short day treatments. Ten long days exposures following 12 increased peduncle length when treatments of 10 SD were short days gave the best spray and peduncle formation (8). compared to 8 and 10 LD, 12 SD were compared to 8 and 10 Kiplinger et al. (4) reported that peduncle length increased LD and so on. Generally as the number of LD is progres as the number of long photoperiods following short days in sively increased terminal and lateral peduncles were length creased. ened. The difficulty in obtaining consistent and significant Increased peduncle length may be associated with cell increases when 10 to 12 SD were followed by 8-10 LD and elongation and Cathey (2) reported that a phytochrome to a lesser degree 14 SD followed by 8-10 LD could have mediated system promotes cell elongation. Low light in been due to the extremely high temperatures that occasion tensities from incandescent lamps (0.5-2.0 fc) applied after ally prevailed during this time of year, which also caused a 12 hr dark period and continued until sunrise promoted flowering delay (Table 1). There was a difference of 16 days internode elongation in chrysanthemums (2). The object of between control and those treatment given 10, 12 and 14 SD this study was to increase peduncle length on commercially although the LD treatments were given only 8 to 10 days. grown chrysanthemums in Florida, by the interrupted photo- 'Iceberg' seemed more temperature sensitive than 'Blue period method during the season when short peduncles Chip', since increased peduncle length on terminal and commonly occurs in the field. lateral spray were less than for Iceberg'. Increased peduncle length did not exceed 35% and the longer time for flower Materials and Methods development indicated the more sensitivity of 'Iceberg' to Rooted cuttings of 'Iceberg' and 'Blue Chip' chrysan high temperatures. themums were obtained from Yoder Brothers Inc., Barber- 'Blue Chip' however, was less sensitive to high tempera ton, Ohio, planted in 15 cm standard clay pots, one plant tures and flowering date followed closely the LD treatment per pot on March 6, 1976 and then placed in a plastic green it was subjected to. The 11 to 13 days of flowering delay house with open sides. The soil mix was pasteurized and when these were subjected 8 to 10 days of LD supported consisted of sand, peat and bark, v:v:v, amended with 5.6 this argument. There was a progressively longer terminal kg superphosphate, 5.6 kg dolomitic limestone and 1 kg of and lateral peduncles when 10 were compared to 12 and 14 Perk2 per m3 of soil mix. Plants were manually watered SD treatments (Table 2). In most instances lateral pedun through a hose supplied with a constant 200 ppm N and K cles developed terminal flower buds with lateral buds (Fig. fertilizer solution. Plants were kept vegetative by lighting 1). Additional increases in peduncle length on 'Blue Chip' them at night from 10 PM to 2 AM from March 6 to March were as much as 250%, especially on the 1st lateral (Table 31 and then lights were turned off and plants shaded with 2). Final ht. of both cultivars were progressively taller as black sateen cloth from 7 PM to 8:30 AM to assure uniform the number of interrupted LD increased. These results in flower bud initiation. dicated that, peduncles of spray mums can be effectively Plants were pinched on March 17 and pruned to 3 stems increased commercially by use of interrupted light, during seasons that, commercial establishments have difficulty pro ducing sprays with adequate peduncle length for retailers.