Days from sowing to anthesis were significantly different among six sunflower (Helianthus annuus L.) cultivars and ranged from 52 days for `Big Smile' to 87 days for `Pacino'. Height ranged from 13.5 cm for `Big Smile' to 37.3 cm for `Pacino'. Postproduction life ranged from 10 days for `Pacino' and `Elf' to 15 days for `Big Smile'. Postproduction quality ratings (1 to 5, with 5 the best) ranged from 3.9 to 5 after 5 days and 1 to 4.2 after 10 days. Quality ratings after 15 days were not significantly different among cultivars, because few plants were marketable at 15 days. Increasing the number of plants per pot from one to three or five reduced number of days to anthesis and postproduction life. Pot sizes of 10-, 13-, or 15-cm diameter, had no influence on production or postproduction characteristics. Promalin (62.5 to 500.0 mg·L–1) was not commercially useful in extending postproduction life. Two cultivars were found to be most suitable for pot production, `Pacino' and `Teddy Bear', with one plant per 15-cm pot and sprayed with B-Nine at 8000 mg·L–1.
Laurence C. Pallez, John M. Dole, and Brian E. Whipker
Jaime K. Morvant, John M. Dole, and Janet C. Cole
Euphorbia pulcherrima `Gutbier V-14 Glory' were grown with 220 mg·liter–1 N (20N–4.4P–16.6K) using ebb-and-flow (EF), capillary mat (CAP), microtube (MIC), and hand-watering (HAN) and were irrigated either daily (pulse - P) or as needed (regular - R). For all irrigation systems, pulse irrigation produced the greatest total dry weight. HAN-R produced lower total dry weight than all other irrigation systems and frequencies. Root dry weight was highest with pulse subirrigation (EF and CAP). MIC-P, EF-P, and EF-R were the most water-efficient treatments. The experiment was repeated twice with similar results. In a second experiment, Pelargonium ×hortorum `Pinto Red' root balls were sliced into three equal segments; top, middle, and bottom. For all irrigation systems, root counts were lowest in the top region. EF root counts were greatest in the middle region, while MIC root counts were greatest in the bottom region. The two subirrigation systems had higher average root counts than the two top-irrigated systems (HAN and MIC). In general, there was less difference in EC between regions for top-irrigated than for subirrigated root balls. The EC was lowest in the bottom and middle regions of EF and the bottom region of MIC and CAP. For subirrigation, the highest EC was in the top region. For all systems, pH was lowest in the bottom region.
Iftikhar Ahmad, Brian E. Whipker, and John M. Dole
Effects of paclobutrazol and ancymidol on postharvest performance and growth control of potted sunflower (Helianthus annuus L.), zinnia (Zinnia elegans Jacq.) and marigold (Tagetes erecta L.), petunia (Petunia ×hybrida Vilm.) plugs, respectively, were studied. Paclobutrazol was applied as a drench at 0, 1.0, 2.0, or 4.0 mg of a.i. per 15.2-cm pot for sunflower and 0, 0.5, 1.0, or 2.0 mg per 12.5-cm pot for zinnia, while ancymidol was applied at 0, 40, 80, and 160 mg·L−1 with a volume of 0.21 L·m−2 as a foliar spray for marigolds or petunia plug crops. With an increase in paclobutrazol dose or ancymidol concentration, plant growth (plant height and diameter, shoot fresh or dry weight) was controlled for all species tested. Use of 1.0–2.0 mg paclobutrazol per pot produced 21% to 28% shorter plants with 12% to 15% smaller plant diameter, 13% to 19% less shoot fresh weight, 15% to 21% less dry weight, and darker green foliage color for potted sunflower than nontreated plants. Treatment with 1.0–4.0 mg paclobutrazol per pot delayed first wilting by 0.7–1.4 days compared with nontreated plants. For zinnia, 0.5–1.0 mg paclobutrazol controlled plant growth, produced dark green foliage, and extended shelf life by delaying first wilting by 2.6–3.9 days and second wilting by 1.4–2.0 days than nontreated plants. For marigold and petunia plugs, 40–80 mg·L−1 ancymidol provided ample growth control with darker green foliage; however, postharvest longevity was extended only when plugs were sprayed with 160 mg·L−1 ancymidol. During simulated storage and shipping, plant growth retardants maintained darker green foliage for potted sunflower, zinnia, and marigold plugs and prevented postharvest stem elongation of petunia plugs. In summary, use of plant growth retardants effectively controlled excessive plant growth and extended shelf life of potted plants and plugs.
John M. Dole, Janet C. Cole, and Sharon L. von Broembsen
`Gutbier V-14 Glory' poinsettias (Euphorbia pulcherrima Willd. Ex. Klotzsch) grown with ebb-and-flow irrigation used the least amount of water and produced the least runoff, and plants grown with capillary mats used the greatest amount of water and produced the most runoff, compared to microtube and hand-watering systems. The maximum amount of water retained by the pots and media was greatest for the microtube and ebb-and-flow systems and became progressively lower for the hand-watering and capillary mat systems. The media and leachate electrical conductivity from plants grown with subirrigation systems was higher than those grown with top irrigation. For the two top-irrigation systems (microtube and hand-watering), plants grown with 250 mg N/liter from a 20N-4.4P-16.6K water-soluble fertilizer had greater leaf, stem, and total dry weights than those grown with 175 mg N/liter. The two subirrigation systems (ebb-and-flow and capillary mat) produced plants that were taller and had greater leaf, stem, and total dry weights when grown with 175 than with 250 mg N/liter. The higher fertilizer concentration led to increased N, P, Fe, and Mn concentration in the foliage. Nitrogen concentration was higher in top-irrigated plants than in subirrigated plants. The ebb-and-flow system produced the greatest total dry weight per liter of water applied and per liter of runoff; capillary mat watering was the least efficient in regard to water applied and runoff.
W. Roland Leatherwood, John M. Dole, and James E. Faust
Ethephon [(2-chloroethyl) phosphonic acid] is used to increase stock plant cutting productivity through increased flower and flower bud abscission and branching. However, ethylene evolution resulting from ethephon application is suspected to cause leaf abscission of unrooted cuttings during shipping. It was the objective of this study to assess ethylene evolution from ethephon-treated cuttings during storage and shipping of unrooted cuttings. Impatiens hawkeri W. Bull ‘Sonic Red’ and ‘Sonic White’ stock plants were treated with 0, 250, 500, or 1000 mg·L−1 ethephon. Cuttings were harvested from 1 to 21 days later and each harvest was stored at 20 °C in sealed jars for 24 h before ethylene measurement. Higher ethephon doses resulted in greater ethylene generation. Cuttings harvested 1 day after treatment with 0, 250, 500, or 1000 mg·L−1 ethephon evolved 0.07, 1.3, 1.7, or 5.8 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. Twenty-one days after treatment, cuttings from the same plants evolved 0.05, 0.05, 0.15, or 0.14 μL·L−1·g−1 (fresh weight) ethylene in the first 24 h of storage at 20 °C, respectively. As cuttings were harvested from Day 1 to Day 21, ethylene concentrations evolved within the first 24 h of storage decreased exponentially. Rinsing cuttings, treated 24 h earlier with 500 mg·L−1 ethephon, by gently agitating for 10 s in deionized water reduced ethylene evolution to 0.7 μL·L−1·g−1 (fresh weight) as compared with 1.7 for unrinsed cuttings. Cuttings harvested 24 h after treatment with 500 mg·L−1 ethephon stored at 10, 15, 20, and 25 °C for 24 h evolved 0.37, 0.81, 2.03, and 3.55 μL·L−1·g−1 (fresh weight) ethylene. The resulting mean temperature coefficient (Q10) for the 10 to 25 °C range from all replications was 5.15 ± 0.85. Thus, ethylene continues to evolve from ethephon-treated Impatiens hawkeri stock plants for up to 21 days and can accumulate to high concentrations during cutting storage.
Iftikhar Ahmad, John M. Dole, and Frank A. Blazich
Effects of harvest time (morning, noon, or afternoon) on water uptake, fresh weight changes, termination symptoms, leaf relative water content (LRWC), carbohydrate status, and vase life of cut ‘ABC Purple’ lisianthus (Eustoma grandiflorum Salisb.), ‘Double Eagle’ African Gold Coin Series marigold (Tagetes erecta L.), and ‘Deep Red’ Benary’s Giant Series zinnia (Zinnia elegans Jacq.) were studied. For stems of lisianthus harvested and then stored in the dark with the basal ends in water for 2 weeks at 3 ± 1 °C, those harvested at noon (1200 hr to 1300 hr) or in the afternoon (1700 hr to 1800 hr) had longer vase life compared with stems harvested in the morning (0700 hr to 0800 hr). However, stems of lisianthus evaluated without storage had no differences in vase life. Stems of marigold harvested in the afternoon had longer vase life than morning- or noon-harvested stems. Time of harvest had no effect on cut flower longevity of zinnia. However, vase life was considerably shorter for stems of all species when tested after 2 weeks storage compared with freshly harvested stems. Stems of zinnia harvested at noon had lower LRWC than morning- or afternoon-harvested stems. Marigold stems harvested in the afternoon and evaluated without storage had lowest LRWC on Day 7 of vase life. Harvest time or storage did not influence LRWC of lisianthus. Stems of marigold and lisianthus harvested at noon or in the afternoon had higher levels of carbohydrates compared with morning-harvested stems, whereas freshly harvested stems had higher concentrations of glucose and sucrose, which decreased during storage or the vase period. Sucrose concentrations varied more significantly among various tissues than other sugars presumably as a result of translocation during vase life. In summary, carbohydrate status of stems harvested at different times of the day varied greatly and affected postharvest longevity of cut marigold and lisianthus, but not zinnia.
John M. Dole, Janet C. Cole, and Vicki Stamback
Rooted cuttings of four woody cut species, Buddleia davidii `Black Knight' (butterfly bush), Forsythia × intermedia `Lynwood Gold', Salix chaenomeloides (Japanese pussywillow), and Salix matsudana `Tortuosa' (corkscrew willow) were planted outdoors in 23 Apr. 1992. During the next year, forsythia, pussywillow, and corkscrew willow plants were either unpruned or pruned to 30–45 cm above the ground: 1) during dormancy or immediately after harvest (winter); 2) 3 to 4 weeks after start of shoot growth (spring); or 3) in early June (summer), and number and length of stems harvested was recorded for three years. Butterfly bush was either unpruned or pruned to 8 cm above the ground during: 1) winter or 2) spring, and number and length of stems recorded for 2 years. Stem length and number increased each year for all four species, and all species produced harvestable stems within 1 year after planting. For forsythia, no differences due to treatment were found, although year by treatment interactions were noted. The unpruned control produced the longest and greatest number of stems for pussy willow. Winter or spring pruning produced the longest and greatest number of stems for corkscrew willow. For butterfly bush, spring or no pruning produced the greatest number of stems, and year by treatment interactions were noted.
Iftikhar Ahmad, John M. Dole, Atyab Amjad, and Sagheer Ahmad
Effects of wet and dry storage methods were compared to improve postharvest performance of specialty cut flower species. While increasing duration of storage reduced vase life, vase life declined less with dry storage for marigold (Tagetes erecta) and rose (Rosa hybrida), but not for zinnia (Zinnia elegans) or lisianthus (Eustoma grandiflorum) over wet storage. Marigold stems had 1.9, 4.6, and 1.5 days longer vase life after 1, 2, or 3 weeks in dry storage, respectively, as compared with storage in water. Zinnia stems did not tolerate either wet or dry storage, while lisianthus stems had a longer vase life when stored in water as compared with dry storage. For rose, dry storage for 2 weeks increased vase life compared with wet storage. Dry stored marigold and lisianthus stems had higher water uptake after being placed in the vase as compared with the stems stored in water, while zinnia and rose had less uptake. Storage method had no effect on leaf relative water content (LRWC) in lisianthus, marigold, and zinnia; however, LRWC decreased with increased storage duration. This necessitates evaluation of storage method and duration effects for each species and cultivar to ensure extended storage life and improve postharvest quality.
Laurence C. Pallez, John M. Dole, and Brian E. Whipker
Sunflower (Helianthus annuus) has potential as a potted flowering plant due to short crop time, ease of propagation, and attractive flowers but postharvest life is short and plants can grow too tall. Days from sowing to anthesis differed significantly among six sunflower cultivars and ranged from 52 days for `Big Smile' to 86 days for `Elf' and `Pacino.' Height ranged from 6.0 inches (15.2 cm) for `Big Smile' to 14.9 inches (37.8 cm) for `Pacino', postproduction life ranged from 10 days for `Elf' and `Pacino' to 15 days for `Big Smile', and postproduction chlorosis ratings (1 to 5, with 5 the least) ranged from 5.0 for `Teddy Bear' to 4.4 for `Big Smile' after 5 days and 4.2 for `Teddy Bear' to 3.1 for `Sunspot' after 10 days. Promalin (a gibberellin and benzyladenine mixture) applied at 62.5 to 500 ppm (mg·L-1) was not commercially useful in extending postproduction life. Increasing pot size from 4 to 6 inches (10 to 15 cm) in diameter decreased postproduction life and plants in 5-inch-diameter (13 cm) pots were tallest. Pots with three plants flowered more quickly than those with one or five plants and pots with five plants had 1 day shorter postharvest life than those with one or three pots. All cultivars were facultative short-day plants, except for `Sundance Kid', which was day neutral. Storing potted sunflowers at 41 °F (5 °C) for 1 week did not reduce postproduction life, which was 11 to 12 d; however, 2 weeks of cold storage resulted in foliar damage. Three cultivars were found to be most suitable for pot production, `Elf', `Pacino' and `Teddy Bear', with one or three plants per 6-inch pot and sprayed with daminozide (B-Nine) at 8,000 ppm, or drenched with paclobutrazol (Bonzi) at 2 mg/pot (a.i.) (28,350 mg = 1.0 oz).
Ben A. Bergmann, John M. Dole, and Ingram McCall
Responses of 14 to 20 poinsettia (Euphorbia pulcherrima) cultivars were assessed following exposure to environmental stressors common in the crop’s postproduction supply chain and consumer environment: low light levels, low temperatures, and low substrate moisture. As indicated by number of days to unacceptable appearance, 14 cultivars tolerated three low light levels (10, 20, and 40 µmol·m–2·s–1) well, with all individuals of six of the cultivars exhibiting an acceptable appearance at 7 weeks when the experiment ended. An experiment with 20 cultivars showed them to be surprisingly tolerant of low temperatures for a short duration, with no differences found when averaging across cultivars among plants exposed to 2, 5, or 20 °C for 2 days. However, all cultivars exposed to 5 °C for 10 days performed poorly. Cultivars differed markedly in response to low substrate moisture, with frequency of unacceptable plants before 4 weeks across all treatments ranging from 0% to 87% among the 14 cultivars tested. Across 17 cultivars, acceptable plant appearance was extended from 23 days for plants that were never irrigated after 10 d in sleeves to 32 days for plants that received a single irrigation at unsleeving and not thereafter. The low temperatures and low substrate moisture experiments were conducted in 2 years, and years differed significantly for nearly all dependent variables assessed. The significant interaction between year and cultivar for all observed variables in those two experiments indicates the importance of conducting experiments such as these over 2 years or more. Potted plants of many of the poinsettia cultivars tested proved to be highly tolerant in terms of low light levels, low temperatures, and low substrate moisture. Three cultivars appeared to be most tolerant in two of the three experiments: Prestige Red (low light levels and low temperatures), Titan Red (low temperatures and low substrate moisture), and Whitestar (low light levels and low substrate moisture). Three cultivars were most tolerant to all three sources of postproduction plant stress: Christmas Day Red, Early Mars Red, and Titan White.