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- Author or Editor: Jeff S. Kuehny x
Lateral branches of poinsettia tend to break from the main stem as plants reach maturity. The cause of poor stem strength is not known; however, suggested factors implicated in poor stem strength are: rate of nitrogen fertilizer used, type of plant growth regulator used, crowding of plants, or stem diameter of the cutting. Four different experiments were conducted to determine if these factors affected stem strength of poinsettia. Experiment 1: `Freedom Red', `Success', `V-17 Angelika Red', `Red Sails', `Nutcracker Red', `Cortez', `Maren', and `Red Splendor' poinsettia were fertilized with 20N–1P0–20K at 75, 75/125, 125/200, or 200 ppm N drip fertigation with zero leachate. Experiment 2: Three plant growth regulators were applied to `Pearl' and `Jolly Red' poinsettias. Experiment 3: `Freedom Red' plants were grown in a 625, 900, 1225, or 1600 cm2 area. Experiment 4: Rooted `Freedom Red' cuttings with stem diameters of 4.5, 5.5, 6.5, or 7.5 mm were used. A force meter was used to determine the strength of each lateral on the main stem of the six replications in each experiment. The lower laterals had the least stem strength and the top lateral had the highest stem strength for all treatments in all experiments. The stem strengths of some cultivars in experiment 1 were stronger at the lower fertilizer rates. Type of plant growth regulator had no significant affect on most poinsettia cultivars. The stem strengths of poinsettias in experiments 3 and 4 varied according to which lateral was measured.
Rhizomes of Curcuma alismatifolia Roxb. `Chiang Mai Pink', C. gracillima Roxb. `Violet', and C. thorelii Roxb. were soaked in gibberellin (GA4+7) at 0, 200, 400, or 600 mg·L-1 (ppm) and planted into 15.2-cm-diameter (6 inches) containers. The plants were grown in a greenhouse at 30 °C day/23 °C night (86.0/73.4 °F) temperatures. When shoot height was 10 cm (3.9 inches), the plants were drenched with 118 mL (3.9 fl oz) of paclobutrazol at 0, 2, 3, or 4 mg a.i. per 15.2-cm-diameter container. Gibberellin4+7 delayed shoot emergence and fl owering but did not affect the fl ower number. Paclobutrazol rates were not effective in controlling height of C. alismatifolia `Chiang Mai Pink' averaging 85 cm (33.5 inches), C. gracillima `Violet' averaging 25 cm (9.8 inches), or C. thorelii averaging 17 cm (6.7 inches). Curcuma alismatifolia `Chiang Mai Pink', C. gracillima `Violet', and C. thorelii had postproduction longevities of 4.6, 2.6 and 3.8 weeks respectively, making these three species of curcuma excellent candidates for use as fl owering pot plants.
This decision case concerns production and marketing problems that many ornamental growers incur. At the retail level, popular ornamental crops are often used as loss leaders to draw the public into stores to make other purchases. As a result, retail buyers are concerned not with quality but with price and volume. To meet the needs of price-conscious buyers, growers may attempt to reduce their production costs by reducing the level of production inputs, with some sacrifice in product quality. The owners of Two Sisters Greenhouses must decide whether they are going to produce lower-quality plants, change marketing strategies, or grow alternative crops to retain their current profit margins. This case study was intended for use in greenhouse management, nursery management, and floriculture courses where students assume the role of a decisionmaker in poinsettia production and marketing.
Several reports suggest that late-planted rhizomes of Curcuma alismatifolia produce their inflorescences in less time than those that have been planted earlier in the forcing season. Two cultivars of this ginger species were removed from the ground in late February following a lengthy dormancy period in the field. About 6 weeks later, after air drying, weekly plantings were initiated through the end of June. Five rhizomes per cultivar were planted singly in 15-cm pots in ProMix BX medium. All plants were forced outdoors under full sun conditions and an overhead spray stake irrigation system that delivered 200 ppm each of nitrogen and potassium with each watering. Cultivar differences were apparent. Plant-to-sprout days for the DP and LP cultivars ranged from 20–51 and 21–57 days, respectively, with means of 3 8 ± 9.2 and 44 ± 11.9 days, respectively, over the 10-week planting cycle. Sprout-to-flower days showed much less difference with ranges of 61–75 and 58–72 days for DP and LP and means of 69 ± 4.3 and 66 ± 4.0 days, respectively. Plant to flower times differed largely because of the length of time required for the rhizomes to sprout rather than for the amount of time spent in inflorescence initiation and development. Plant heights at flowering and inflorescence counts were not different within cultivars over the 10-week planting period. Degree days and solar integrals will be presented for the 10 growing periods.
Gingers are tropical perennials from the Zingiberaceae family with attractive long-lived flowers that can be grown as potted plants in subtropical and temperate zones under protected conditions. Development of production practices for this new flowering pot crop is essential for optimum plant growth. The effect of photoperiod on growth and flowering was evaluated on Curcuma gracillima, C. cordata, C. alismatifolia, C. petiolata `Emperor', Curcuma `Chang Mai dwarf', Siphonichilus decora, and S. kirkii. Plants were grown under daylengths of 8, 12, 16, and 20 h. Plant height, number of new leaves, number of shoots, and leaf area were larger for plants growing under an extended daylength (16- and 20-h photo-period) than for plants under 8 and 12 h. Plants grown under an 8-h daylength approached dormancy sooner than those growing under 12, 16, or 20 h of light, and no flowering occurred.
Herbaceous perennials are one of the fastest growing ornamental sectors in the United States. Current production recommendations do not address the effect of environmental factors, such as high temperature, on growth of herbaceous perennials. The focus of this research was to determine how supra-optimal temperatures effect growth and photosynthesis. Plants were exposed to a high temperature of 35 °C and photosynthesis measurements were recorded over a 6-week period at 1100, 1300, and 1500 hr. Results indicate that the time of day the measurements were taken made little difference on rate of photosynthesis and that there was a similar trend in photosynthetic rate over the 6-week period. Photosynthesis decreased as the plants began to flower and then increased until the onset of flower senescence. Plants grown at supraoptimal and optimal conditions had a similar trend and rate of photosynthesis throughout the 6-week period. Plant growth significantly decreased as the duration of high temperature increased for both species; however, Gaillardia was more heat tolerant then Coreopsis.
Curcuma alismatifolia `Chiang Mai Pink' is a tropical perennial from the Zingiberaceae family with attractive flowers that make it useful as potted plant. Curcuma alismatifolia produces a tall inflorescence resulting in an unmarketable plant due to excessive height. Rhizomes of C. alismatifolia were soaked for 10 minutes in GA at concentrations of 0, 100, 200 or 500 ppm. The same plants were drenched with paclobutrazol at 0, 2, 3 or 4 mg a.i./container when shoots were 10 cm. GA significantly delayed rhizome emergence and flowering and reduced flower height. Paclobutrazol significantly reduced height; however, greater concentrations must be applied to obtain a marketable plant height. Number of flowering stems, postproduction life, and postproduction stretching were not affected by GA or paclobutrazol. Curcuma alismatifolia had an excellent postproduction life (4.64 ± 0.28 weeks) with little postproduction stretching (2.27 ± 0.38 cm).
Coreopsis and Gaillardia were exposed to supra-optimal temperatures of 35 °C for a 6-week period beginning at flower initiation. Photosynthesis measurements were recorded at 1100 hr, 1300 hr, and 1500 hr for 3 days each week and carbohydrate partitioning was determined once per week. Results indicate that the time of day the measurements were taken made little difference on rate of photosynthesis and that there was a similar trend in photosynthetic rate over the 6-week period. Photosynthesis decreased as the plants began to flower and then increased until the onset of flower senescence. The patterns of carbohydrate partitioning were similar to those observed for photosynthesis. The plants grown at supra-optimal and optimal conditions had a similar trend and rate of photosynthesis throughout the 6-week period. Plant growth and total carbohydrates significantly decreased as the duration of high temperature increased for both species, however Gaillardia was more heat tolerant than Coreopsis.
The demand for new and/or improved herbaceous annuals and perennials continues to increase, making information on production and viability of these plants a necessity. In Louisiana and the Southern U.S., one of the greatest impediments to production of marketable herbaceous plants and their longevity is high temperature. Herbaceous plants have various stages of vegetative growth and flowering; high temperatures during these developmental stages can have a tremendous impact on plant metabolism, and thus plant growth and development. The goal of this research was to better understand the differences between heat tolerant (HT) and heat sensitive (HS) species and cultivars at various high temperatures in terms of whole plant growth, flowering, photosynthesis, carbohydrate content, electrolyte leakage, chlorophyll content and plant small heat shock proteins (HSP) expression levels. Salvia splendens Vista Series (HT), Sizzler series (HS); Viola witrokiana `Crystal Bowl Purple' (HT), `Majestic Giant Red Blotch' (HS), F1 Nature Series (HT) and F1 Iona Series (HS); Gaillardia × grandiflora `Goblin' (HT) and Coreopsis grandiflora `Early Sunrise' (HS) were grown from seed in growth chambers under 25/18 °C (day/night) cycles. Plants at 4, 6, and 8 weeks after germination were subjected to different high temperature treatments of 25 (control), 30, 35, 40, and 45 °C for 3 h. Results show that there was a significant difference in net photosynthesis, electrolyte leakage, soluble carbohydrate content and HSP levels between HT and HS cultivars. Effects of high temperature on plant growth, chlorophyll content, and number of days to flower, flower size, and marketable quality were also significantly different.