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- Author or Editor: John M. Dole x
Water quality has become a significant issue in the nursery industry. Local testing of runoff contamination from nursery production is, however, of little value to other growers because of the variation in management practices and nursery layouts. Two nursery blocks have been designed and constructed to test runoff from production with sprinkler and drip irrigation systems in combination with constant liquid fertilization and controlled release fertilizers. Management practices using various combinations of irrigation systems with fertilizer application rates are being tested in a small area with reasonable control of inputs. Preliminary data has shown no difference in plant response to irrigation method, but runoff was significantly reduced with drip irrigation. Plant quality was better with controlled release fertilizer, which generally yielded less N and P contamination in runoff, than constant liquid fertilization except during extremely hot weather.
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.
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.
Postharvest environments during storage and shipping are often conducive to plant stress and disease development. Liners of four cultivars of geraniums (Pelargonium ×hortorum) were evaluated every 2 days for their susceptibility to gray mold (Botrytis cinerea) and leaf yellowing over an 8-day simulated shipping period at either constant air temperature of 15 °C or variable air temperatures cycling every 24 hours between 10 and 30 °C. The latter treatment was created using air temperature logs of commercial liner shipments sent to five locations during Spring 2016 and Fall 2016. We sprayed a spore suspension of 2 × 104 or 2 × 106 to inoculate liners before they were subjected to the two temperature treatments. Disease ratings did not reach significant levels for the dry control until day 6 of storage. Regardless of the spore concentration, ratings were similar for inoculated cuttings. Independent of the storage temperature and spore concentration, liners developed minor lesions by day 2 of storage. Cultivars varied slightly in disease ratings, with Tango Dark Red being the most susceptible, followed by Patriot Bright Red, Patriot Rose Pink, and Americana Red. During the 8-day incubation period, ‘Patriot Rose Pink’ developed the most leaf yellowing compared with the other three cultivars. Liners that experienced variable air temperatures had marginal leaf yellowing by day 2, and this yellowing increased throughout the experiment. Liners placed at 15 °C had ≈50% less leaf yellowing compared with liners exposed to variable air temperatures until day 8, when leaf yellowing was similar between the two air temperature treatments. Disease caused by B. cinerea was avoided when simulated shipping was 2 days or fewer, and a stable air temperature of 15 °C reduced leaf yellowing on geranium liners compared with variable air temperatures.
Anemone (Anemone coronaria L.), snapdragon (Antirrhinum majus L.), larkspur [Consolida ambigua (L.) P.W. Ball & Heyw.], delphinium (Delphinium ×cultorum Voss.), sunflower (Helianthus annuus L.), lupine (Lupinus hartwegii Lindl.), stock [Matthiola incana (L.) R. Br.], and pansy (Viola ×wittrockiana Gams.) were grown in raised sandy loam ground beds in double-layered polyethylene-covered greenhouses which were either unheated (ambient) or had a 55 °F (13 °C) minimum night temperature in year 1 and 36 or 50 °F (2 or 10 °C) minimum night temperature in year 2. Results were species specific; however, the extreme low temperatures [21 °F (-6 °C)] in the unheated house limited delphinium and lupine production. The warmest greenhouses (55 and 50 °F) reduced production time for anemone, delphinium, larkspur, lupine (year 2), snapdragon (year 2),stock, and sunflower. The coolest greenhouses (unheated and 36 °F) increased stem lengths for anemone (year 2), delphinium, larkspur (year 1), lupine (year 2), snapdragon, stock, and sunflower. The coolest green-houses also yielded a profit or lower net loss for all species except delphinium, lupine, and snapdragon (year 2) for which profits were highest or net losses were lowest in the warmest greenhouses.
Various postharvest procedures were conducted on several rose (Rosa hybrida) cultivars to determine the effects on vase life, water uptake, change in fresh weight, stage of opening, and vase life termination criteria. Vase life was influenced by cultivar and vase solution. Commercial preservative solutions resulted in a longer vase life, smaller decrease in fresh weight than the controls, and smaller increase in water uptake. Vase life of nine cultivars in distilled water ranged from a low of 7.1 days for Queen 2000 to a high of 15.3 days for Forever Young. Flower termination criteria were also cultivar specific with Black Baccara, Classy, and Charlotte most prone to bent neck and blackening of petal tips. Exogenous ethylene at 0.4 or 4.0 μL·L−1 did not affect vase life but lowered water uptake. Application of the antiethylene agent silver thiosulfate (STS) at 0.2 mm concentration significantly improved vase life in five out of the nine cultivars (Anna, Charlotte, First Red, Freedom, and Konfetti) tested, but 1-methylcyclopropene (1-MCP) at 740 nL·L−1 did not improve vase life over the control. Both vase life and water uptake were reduced when more than one stem was placed in a vase; placing 10 stems in a vase shortened vase life by 1.4 days and impeded water uptake by up to 10.6 mL/stem per day. Increasing the amount of time stems remained dry before placing in a vase reduced vase life, but recutting immediately before placing in a vase minimized the decline. Increasing the amount of stem cut off the base up to 10 cm increased vase life.
Effects of pulsing with different concentrations of gibberellin plus benzyladenine (GA4+7 + BA), a proprietary mixture of GA4+7 plus BA in a commercial floral preservative (GA4+7 + BA + preservative), or a propriety mixture of sugar plus acidifier developed for bulbous flowers (floral bulb preservative) were studied on postharvest performance and quality of cut lily (Lilium hybrids) and gladiolus (Gladiolus hybrids) flowers. Pulsing of cut stems of lily with GA4+7 + BA at 5 or 2 mL·L−1 GA4+7 + BA + preservative for 20 hours at 3 ± 1 °C extended the vase life and controlled leaf chlorosis of ‘Cobra’ oriental lily and ‘Cappuccino’ and ‘Dot Com’ asiatic lily. Cut ‘Orange Art’ asiatic lily performed best when pulsed with GA4+7 + BA at 10 mg·L−1. For cut gladiolus, pulsing with GA4+7 + BA at 10 mg·L−1 extended the vase life of ‘Alice’, ‘Mammoth’, and ‘Passion’, while ‘Scarlet’ had the longest vase life when pulsed with 5 mg·L−1 GA4+7 + BA. GA4+7 + BA + preservative also extended the vase life and controlled leaf chlorosis, but the floral bulb preservative had no effect on vase life extension or preventing leaf chlorosis of lilies. Gladiolus cultivars had no or minor leaf chlorosis during vase period. Overall, overnight pulsing with GA4+7 + BA or GA4+7 + BA + preservative extended the vase life and prevented leaf chlorosis and can be used by growers and wholesalers for maintaining quality of cut stems.
Influence of season of the year, cutting week within a propagation cycle (number of weeks from which a stock plant has been harvested), stock plant age, and rooting compound on postpropagation cutting quality, and adventitious rooting was examined for ‘Stained Glass’ coleus (Solenostemon scutellarioides). Cuttings were of higher quality and produced more robust root systems when a propagation cycle started in summer vs. fall or spring even when cuttings were harvested from stock plants of the same age. Cutting week within a propagation cycle significantly influenced postpropagation cutting quality and rooting when cuttings were harvested over many weeks from the same stock plants and when cuttings were harvested for three propagation events using stock plants of different ages. When cuttings were harvested on the same days from stock plants of three distinct ages, cuttings harvested in the first week were larger with greater root weights but had more yellowed leaves and lower quality ratings compared with the two subsequent cutting weeks, but stock plant age had no effect on any observed parameter. Treatment with rooting compound did not overcome the significant influences of season and cutting week within a propagation cycle whether rooting was carried out in a greenhouse or growth chamber. Shoot and root fresh and dry weights were positively correlated with both daylength and midday instantaneous light of the stock plant environment.
Increasing cut stem length and reducing crop production time are producers’ goals for numerous cut flower species. One or both of these aims was met in several field-grown cultivars through foliar application of gibberellic acid (GA3), but effectiveness varied by cultivar, application rate, and timing. Of the 13 cultivars tested, stem length was increased in nine cultivars [Toreador Red celosia (Celosia argentea), Camelot White foxglove (Digitalis purpurea), Imperial Giants Pink Perfection larkspur (Larkspur hybrids), Compliment mix lobelia (Lobelia hybrids), Nippon Taka ornamental pepper (Capsicum annuum), Amazon Neon Duo and Bouquet Purple sweet william (Dianthus hybrids), Summer Pastels yarrow (Achillea millefolium), and Benary’s Giant Scarlet zinnia (Zinnia elegans)], and time to harvest was decreased in four cultivars [High Tide White ageratum (Ageratum houstonianum), lobelia, ornamental pepper, and zinnia], when GA3 was applied as a foliar spray. Concentrations of 400, 800, and 1600 mg·L−1 GA3 were most effective. Application of GA3 resulted in malformed or smaller flowers or lighter green foliage in foxglove, lobelia, sweet william, and zinnia. In most cases, only one application was tested, and greatest response to GA3 was observed during 3–6 weeks post application. Gibberellic acid did not influence stem length in three cultivars [High Tide White ageratum, Aurora Deep Purple delphinium (Delphinium hybrids), and Column Lilac Lavender stock (Matthiola incana)], and decreased flower stem length in one cultivar (High Tide Blue ageratum). Four cultivars were identified as good candidates for further research given their promising responses to GA3 treatments.
Present status and future prospects of cut rose (Rosa ×hybrida) flower production and postharvest management in Punjab, Pakistan, were investigated. Cut roses were the leading flower crop in the area under study, but production systems and practices were outdated and primitive, resulting in cut stems that were not acceptable in international markets. The majority of growers (65%) had only basic education (grade 10 or less) and 57% had small landholdings (<1 ha); therefore, they did not have modern production techniques and resources for high-quality cut rose production. Moreover, lack of production and postharvest facilities, ignorance of both public and private resources, and poor production and postharvest practices were prevalent. Growers' training regarding production and postharvest management would be required to lift the quality standards of this industry up to the international level. However, a positive trend was observed in cut rose businesses as more than half of growers (52%) entered into the business during last 5 years. In addition, 30% of growers were in business over 10 years, indicating that cut rose production can provide a sustained income for producers. This analysis of the cut rose industry in Punjab can serve as a model for other countries whose cut flowers industries are at a similar stage of development.