Holding practices for balled and burlapped conifers may inadvertently impact nutrient availability and tree growth. The objective of this study was to examine the effectiveness of several nutrient treatments to maintain or enhance the growth and foliar nutrition of Colorado spruce (Picea pungens Engelm.) trees while they were in a mulch-holding bed. Sixty 1.5 to 1.8-m tall Colorado spruce trees with 61-cm (24 inch) diameter root balls were heeled into a holding bed of fresh pine bark mulch during 2002 and 2003. The treatments applied to the root balls were a control (pine bark without fertilizer), 114.2 g Osmocote (Scotts, Marysville, OH) 15N–3.9P–10K distributed over the top of the ball, one Ross Gro-Stake (Easy Gardener, Waco, TX) 10N–4.3P–8.3K Evergreen fertilizer spike (113 g) per ball, one-half cartridge (≈8.5 g) of Ross Root Feeder (Weatherly Consumer Products, Lexington, KY) 10N–5.2P–10K evergreen fertilizer injected into the root ball at four points, or a 1:1 biosolids-based compost:pine bark mixture (by volume). Trunk diameters and tree heights were measured and foliar samples for nutrient analyses were collected before applying these treatments and at the end of the growing season 20 or 17 weeks later. The 2003 trees were transplanted to a landscape site in 2004, and the height growth of their terminal leaders were measured at the end of the next two growing seasons. Overall, Colorado spruce trees appeared normal while they were held in the mulch beds the first season after nursery harvest. Changes in tree height and trunk diameter by the end of the first season after harvest were unaffected by the nutrient treatments. By fall of both years, needles from trees treated with the mixture of 1:1 compost:bark had the highest levels of foliar N, Mg, Ca, S, and B. Trees treated with the fertilizer spike in 2002 had similar levels of N and S in their needles compared with compost:bark-treated trees, whereas in 2003, spike-treated trees had the second highest levels of foliar N and S, and these levels were significantly higher than those of trees receiving the control or other fertilizer treatments with the exception of N in needles from fertilizer-injected trees in 2002. Plant-available N, however, was highest in the root balls of Osmocote- and fertilizer spike-treated trees only in 2003. Leaders on the 2003 trees that received the compost:bark or fertilizer spike treatments grew at least 70% or 36% taller, respectively, than those trees receiving the other treatments by the end of the second growing season in a managed landscape. Although all nutrient treatments failed to promote increases in tree heights and trunk diameters while the trees were held in a mulch bed for the first growing season after digging, the compost:bark mixture and, to some extent, the fertilizer spike improved foliar nutrition during this time.
Robert R. Tripepi, Mary W. George, K. Amanda Linskey, John E. Lloyd, and Jennifer L. Van Wagoner
Anne Marie Johnson and Ted Whitwell
Twenty-nine annual and perennial wildflower species were evaluated for sod development based on ratings for appearance, root mat density, and stability following undercutting and storage and performance after replanting. Species selection was based on the lack of a large taproot, adaptability to the southeastern climate, flowering period, and potential for surviving root undercutting. Species were seeded in fall and spring, and leaf area and root mass samples were compared. Wildflower sod was undercut at a 5 cm (2 in) depth in March (fall-seeded plots) and May (spring-seeded plots) and then stored on clear plastic for 7 weeks and replanted. Fall-planted species had a higher survival rate than spring-planted species. Species selected for sod development were Achillea millefolium L., Chrysanthemum leucanthemum L., Coreopsis lanceolata L., Coreopsis tinctoria Nutt., Gaillardia aristata Foug., Monarda citriodora Cerv. ex Lag., Rudbeckia hirta L., and Verbena tenuisecta Briq. To reduce damage to aerial growth during harvesting, paclobutrazol, daminozide, and uniconazole were tested on eight greenhouse-grown wildflower species. Uniconazole had limited growth control over Rudbeckia hirta, Monarda citriodora, Coreopsis lanceolata, and Coreopsis tinctoria.
Maegen Lewis, Melanie Stock, Brent Black, Dan Drost, and Xin Dai
found between the percentage of stems within each grade. Discussion Snapdragon harvests from high tunnels began 3 weeks before the last frost date, 5 to 8 weeks earlier than field harvests, produced fewer culls, and had a greater percentage
Anne M. Hanchek and Arthur C. Cameron
The effect of harvest dates between September and December on regrowth after storage of field-grown Coreopsis grandiflora Hogg × Sweet `Sunburst' and `Sunray', Geum quellyon Sweet `Mrs. Bradshaw', Gypsophila paniculata L. `Snowflake', Iberis sempervirens L. `Snowflake', and Dicentra spectabilis (L.) Lem. crowns was determined. After 0 to 7 months of storage at 0C, stored crowns were repotted and grown in a greenhouse. Plants from later harvests were of higher quality than those from earlier harvests, showing higher rates of survival after longer storage periods, less mold development in storage, and stronger regrowth after storage. Late field harvest is recommended for optimum storage quality.
Graeme A. King and Stephen C. Morris
The postharvest senescence of broccoli (Brassica oleracea L. Italica group) was studied immediately after harvest until senescence was essentially completed at 20C. Changes in respiration, ethylene production, and color were determined for florets, branchlets, and heads of three cultivars of field-harvested `Green Beauty', `Dominator', and `Shogun' broccoli. Changes in respiration and ethylene production were also determined for 3 hours of preharvest and 24 hours of postharvest storage using broccoli grown in containers. Carbon dioxide produced from heads of container-grown broccoli and from heads, branchlets, and florets of field-harvested broccoli decreased markedly during the first 12 hours of postharvest storage before stabilizing. The respiratory quotient shifted toward a more oxidative metabolism in parallel with the respiratory decline. Ethylene production during storage showed no consistent relationship to yellowing. However, time until onset of yellowing was broadly related to the basal levels of ethylene production. The maximum storage life at 20C is ≈72 hours. Branchlets are useful model systems for investigating broccoli senescence.
The effects of inoculum, surface wetness, and stem scar on postharvest fungal infection of highbush blueberry (Vaccinium corymbosum L.) fruit were evaluated by exposing berries of the cultivars Bluechip (small, dry stem scar) and Blueray (large, wet stem scar) to infested and noninfested surfaces under wet or dry conditions. Rots caused by Colletotrichum gloeosporioides (Penz.) Penz. & Sacc. in Penz. and Alternaria tenuissima (Kunze:Fr.) Wiltshire were evaluated. Field-harvested berries stored for 7 days at 21 °C resulted in baseline infection levels of 1.5% (`Bluechip') and 18.7% (`Blueray') for C. gloeosporioides, and 10.1% vs. 28.9%, respectively, for A. tenuissima. Wet stem scars, infestation of handling surfaces, and addition of moisture were all responsible for increasing postharvest rots; however, most of the significant increases in rots occurred with a combination of two or more of these factors.
G.M. Volk and K. Richards
Preservation methods were evaluated for jerusalem artichokes (Helianthus tuberosus L.) to facilitate the back-up of field collections. In vitro plant cultures were established from field-harvested tubers for nine jerusalem artichoke cultivars obtained from the Plant Gene Resources of Canada, Saskatoon Research Center, Saskatoon, Canada. Most cultivars could be maintained at 5 °C or under 25 °C growth room conditions for at least 6 months. Excised shoot tips from in vitro cultures were cryopreserved using plant vitrification solution 2 (PVS2; 15% w/v ethylene glycol, 15% w/v dimethyl sulfoxide, 30% w/v glycerol, and 13.7% w/v sucrose in half strength media salts) as a cryoprotectant. PVS2 exposures of 15 or 30 min at 0 °C resulted in an average regrowth of 34% across five jerusalem artichoke cultivars after liquid nitrogen exposure. Jerusalem artichokes can be successfully maintained using both reduced temperature and cryopreservation approaches.
The European Union's fruit industry is currently beset by marked surplus output, formidable market competition from non-EU countries, and strong consumer demanded for enhanced quality. This latter issue is particularly complex because it involves not only the fruit's genetic, esthetic, sensory, and taste characters, but also pre- and postharvest produce management practices and their impact on the environment and human health. The main thrust of the response to the challenges posed by these quality factors is integrated fruit production (IFP), a policy sustainable crop growing that the EU can support financially. Research has been directly involved in IFP and the directions in which it is moving. It has developed the first EU guidelines (OILB-ISHS), which initially covered pome crops and were later extended to cover all fruits, and the field, harvest, handling, storage, and market monitoring and quality-control techniques needed to implement them. These methods include biological and integrated disease and pest control, the introduction of plant material resistant to biotic and abiotic stresses, the development of field management practices to enhance plant defense and cropping-control mechanisms, the use of energy-saving irrigation and nutrient input techniques, the modeling of plantations, training systems and tree-bearing control, and advanced fruit storage, packaging, and transport methods. The updated advances in these areas are reported and discussed.
Patricia R. Knight, J. Roger Harris, and Jody K. Fanelli
Root severance during field harvesting alters the water status of a tree, resulting in water stress and reduced post-transplant growth. Two experiments, using Acer rubrum L. (red maple), determined the influence of root severance at harvest on sap flow and xylem embolism. Trees 1.5–1.8 m tall (4 years old) were utilized in the first experiment, and trees 1.2–1.5 m tall (2 years old) were utilized in the second. Sap flow sensors were installed on the 4-year-old trees prior to root severance and remained on the trees until 1 week after harvest. Within 1 day after root severance sap flow was reduced and remained lower than nontransplanted (control) trees for the remainder of the experiment. Leaf stomatal conductance (Cs) of transplanted trees 1 week after root severance was lower than that of control trees, but leaf water potentials (ψ) were similar. In the second experiment, sap flow was reduced relative to control trees within 2 h after root severance. Although Cs was reduced 4 hours after root severance, ψ was not. Embolism increased within 24 hours of root severance. These results indicate that root severance quickly induces increased levels of embolism, which is associated with reduced sap flow.
Jorge Ferreira, Denys Charles, James Simon, and Jules Janick
Postharvest methods of handling Artemisia annua L. were evaluated to determine the recovery of artemisinin, a sesquiterpene used in the treatment of malaria, because low yields have been a limitation to commercialization. Immediately following field harvest in October, plants were subjected to: freeze drying, oven drying (40C), and open air drying. Leaf samples (50 gfw) were dried for 7 days in each treatment, and stable weights were achieved after day 2 for oven or open air drying and day 1 for freeze drying. One gram of dry weight was sampled from each treatment for artemisinin analysis using reverse phase chromatography by HPLC with EC detection. Open air drying of samples gave significantly higher artemisinin yield (0.13g/100g) than oven drying (0.10g/100g) and freeze drying (0.02g/100g). In a second experiment, open air drying for 2,4,6, and 8 days was compared to microwave drying for 2 minutes, of foliage samples with 10 gfw, of a plant low in artemisinin. Time of drying did not affect artemisinin content but microwave drying greatly reduced artemisinin (0.02g/100g air drying vs 0.002g/100g microwave drying). In our protocol artemisinin was detected in a greenhouse plant (0.3g/100g artemisinin) in samples as low as 50 mgdw.